Hort couture or hubris? The growing trend of genetically engineered novelty plants

A few months ago I wrote about the newly released Purple Tomato, one of the first direct-to-consumer genetically engineered plants made available to the general public. (I’m happy to report that my Purple Tomato seedlings are growing along quite well.) Shortly after I wrote that article, I learned about another new genetically engineered plant being released to home gardeners, this time a bioluminescent petunia. So, of course you know I just had to have some.

The Firefly Petunia was released recently from Light Bio, a company based in Idaho.  The company states that they grew out 50,000 plants for initial sale, but have worked with third-party growers to grow out additional plants from cuttings due to high demand for the plants.

The petunia itself is pretty nondescript. It is a small-flowered, white variety that wouldn’t get a second glance at a garden center. But the company introduced a set of genes from a bioluminescent mushroom called Neonothopanus nambi  that make the faster growing parts of the plants (mainly flowers, but also other growing points) glow. The glowing is caused by a reaction between enzymes and a class of chemicals called, funnily enough, luciferins. And this is bioluminescence – it glows all the time in the dark. It isn’t like a “glow in the dark” where they have to charge up with a light source and only glow for so long.

How a mushroom gets its glow
Neonothopanus nambi daytime look to night time look Source: Science News

Just like the petunia, the fungus is pretty nondescript during the daytime, but glows brightly once darkness descends. I’ve seen glowing fungus once in my life. As a kid I once saw what is called Foxfire, a glowing fungus on some decaying logs. It is pretty cool seeing something glowing so eerily in nature. Now, I have that same glow in my garden.

Back to the plants. The plants are a bit of investment, ringing in at $29 per plant plus shipping, but there are some price breaks at higher quantities if you order several or put together a group order. As a startup, I suppose the company is banking on the novelty of the plant to demand such a high price to cover costs. According to several sources, these white petunias are just the start. They’re working on roses, houseplants and more.

But why glowing petunias?

Before I placed my order, I had to take a step back and think about why. Why a glowing petunia? With the tomato there is at least the case of increased health properties with added anthocyanins. But what is a value of a glowing petunia other than a novelty? Is there a purpose? Or is it just hubris? And why are there genetically engineered plants on the market all of a sudden?

While the petunias don’t have a culinary or health value, the value that they bring is one of acceptance and familiarity. For decades now, well organized and funded campaigns have spread fear of genetic engineering. Seed companies embraced “Non-GMO” as a marketing scare tactic to drive up sales due to a fake boogie man. And even bottled water and salt are labeled as “Non-GMO”. But it seems that the tide of public opinion seems like it might be turning.

Seeing the excitement around both the Purple Tomato and this bioluminescent petunia seems to show a growing interest, or at least a waning of distrust, in genetically engineered plants. And It think that is one of the benefits, or maybe the causes, of seeing genetically engineered plants on the market. Researchers have found that the online conversation about genetically engineered organisms seems to be shifting – from less polarized to increasingly favorable.

While there are sill some hiccups and some ethical and environmental issues, most scientists see genetic engineering as the most important tool in addressing issues such as endemic plant diseases affecting staple crops and developing plants that can withstand warmer and drier conditions as the climate changes. In order for us to be able to fully use these tools, the conversation needs to continue to shift to a more favorable position.

Starting off with tomatoes, petunias, and other flowers is also a choice of ease. Growing plants that don’t have native counterparts where there could be unintentional spread of genes in the wild reduces some of the regulatory hurdles plants face in the United States. And while the purple genes introduced into tomatoes could spread to plants in the food supply, the safety risk is minimal. It would be much harder to get approval for, say, a genetically engineered sunflower or coneflower where there are wild-growing natives into which the glowing genes could inadvertently spread.

Why are genetically engineered plants popping up all of a sudden?

Probably one of the reasons we are seeing so many new genetic engineering projects now is that it is so much easier. With the discovery of CRISPR-Cas9 technology, it is much easier for scientists to transform plants with DNA insertions or extractions. This technology has revolutionized the world of genetics and genetic engineering not only in the plant world, but also in the areas of human health and more.

Before CRISPR, there were a few methods of introducing DNA into organisms. The most common one for plants was probably using a plasmid from the bacterium Agrobacterium tumefasciens. This is the cause of crown gall and it works by inserting its own ring of DNA, called a plasmid, into the DNA of the plant. The plant then produces proteins based on the virulent DNA and also replicates the DNA. One of the common method was bombardment, putting the DNA on tiny microscopic beads, usually gold, and shooting them into the tissue. Tobacco mosaic virus was also used for plant genetic transformations, especially in related plants such as tobacco, tomato, and…..petunia. Most of the work I did in undergrad was with the commonly used with model plant Arabidopsis thaliana (mouse-ear cress).

The transformation, or success, rates for these methods was relatively low compared to CRISPR. Plus, where the DNA ended up was random. There was no control over where the new snippets of DNA ended up, or what genes they would disrupt, or knock-out, in the process. I did quite a bit of research as an undergrad on figuring out just what genes were knocked out in certain transformations and what that changed in their physiology or response to stimuli (our research focus was gravitropism and response to red light).

CRISPR has taken away the guessing game from genetic transformations. Scientists can now target exactly where they want genes to be inserted, or in some cases “knocked out” or interrupted so they are not expressed. For example, Arctic Apples were developed by knocking out the gene in apples that makes polyphenol oxidase, the enzyme that causes them to turn brown after cutting. This has created a technology that has the potential to substantially reduce food waste in crops that have similar reactions as well, such as potato.

So I think the trend of genetically engineered plants for consumers will continue to grow. Evolving from novelty plants to plants that serve a higher purposes, such as nutritional value enhancements, climate change resistance, and more. It will take us a while to get there, but as the technology advances so does, it seems, public opinion. Until then, I’ll just enjoy my glowing petunias and purple tomatoes.

Additional Sources

https://www.scientificamerican.com/article/this-genetically-engineered-petunia-glows-in-the-dark-and-could-be-yours-for-29/

https://www.science.org/content/article/mushrooms-give-plants-green-light-glow

https://www.fastcompany.com/91073850/glow-in-the-dark-petunias-are-just-the-beginning

¡Escandalo! Seedy mixup results in #Jalapeñogate drama across the US

There’s a scandal simmering all across the United States that brings to mind a switched at birth storyline on a steamy soap opera or telenovela.  This scandal, though, isn’t about babies, its about….peppers!  Jalapeño peppers, to be exact. 

The issue, dubbed #Jalapeñogate online, has many home gardeners scratching their heads as to the identity or the issue with the peppers that they planted. You see, instead of those glossy dark green peppers that many are used to putting in their salsas and other favorite spicy dishes, the plants are producing bright yellow peppers.  Some of them are the same shape as jalapeños and some look more like banana peppers. 

A local gardener allowed me to stop by and let me check out their mysterious peppers.

The phenomenon has gardeners, farmers, and officials in multiple states scratching their heads. It turns out there are no stolen tapes with evidence of the problem. Instead, I was first alerted to the problem when some of the garden Facebook groups in Nebraska were abuzz with posts about the mystery peppers.  I’ve since seen news I’ve seen the issue mentioned in news articles from Oklahoma, Kansas, and California and have seen posts on social media sites such as Reddit and TikTok. I scoured many of these sources (TikTok was surprisingly the most informative) and confirmed it with info from friends in the seed industry.

So what happened?  It turns out that the seed trade is global and multi-tiered and sometimes mix ups occur.  It just so happened that this year there were a lot of them.  One US seed company that supplies a lot of seeds to nurseries and other seed companies, called Seeds by Design, imported some of its seeds for the current season.  The company supplies many interesting and niche seeds, many of which it develops or breeds (they are responsible for the award winning Chef’s Choice tomato series and several other vegetable cultivars that you’d recognize on the seed rack). But it also purchases or imports seeds often for more common varieties.  Seeds by Design supplies seeds to many nurseries, growers, and even seed companies around the country. And that’s where the trouble starts. 

I mentioned #Jalapeñogate on our TV show Backyard Farmer, which fanned the fiery (and not so fiery) pepper flames in Nebraska.

The company imported seeds from an international grower that turned out to be mislabeled.  Up to five different cultivars were accidentally swapped and resulted in pepper pandemonium across the country.  It turns out that more than jalapeños were affected, so we should really change it to just #Peppergate. Here’s what was switched:

What was supposed to be Turned out to be…
Jalapeño (green cultivar) Jalapeño ‘Caloro’ (yellow cultivar)
Jalapeño ‘Tam’ (mild green) Sweet banana pepper
Hungarian Sweet Wax Bell Pepper ‘Diamond’
Bell Pepper ‘Chocolate Beauty’Sweet Pepper ‘Red Cherry’
Bell Pepper ‘Purple Beauty’ Hungarian Hot Wax

Gardeners could have bought these at local garden centers or nurseries as transplants.  I know of at least two local/regional garden centers that sold the affected plants.  I’ve also seen that gardeners who bought seeds from some suppliers (I’ve only seen Ferry-Morse so far) may have received at least switched bell peppers.

Nebraska gardeners (at least 90 of them) were quick to share their #Peppergate story with me.

What does this say about our seed and food supply?

Our food system and our seed system are global.  We live in a global economy and companies buy and trade with each other all the time.  Given the scale of this trade, mistakes can and do happen.  I’ve seen some people try to drag Seeds by Design because they purchased seeds from a foreign company that just happens to be in China. But the company doesn’t deserve that. They had no knowledge of the mix up until the peppers were in the hands of growers and peppers didn’t look right. Can you tell the difference between pepper cultivars by seed?

And others have tried to make an issue about trading with China with some comments that hint at outright racism. While there are some security concerns about trading with countries like China, especially in the tech world, trading simple commodities like Jalapeño seeds is standard practice. I’ve also seen comments that importing ag products from other countries means that we can’t support ourselves. But it turns out that we sell a whole lot more agricultural goods to China than we buy.  US producers sold a record-breaking $200 billion (with a b) worth of agricultural products to China in 2022 while we imported $9.5 billion from them.

Given the need to feed so many people economically, we often import from countries that have better capacity to grow what we need due to climate, land, and labor differences.  We also have to take into account seasonal differences.  Even US based seed production companies and breeders will grow in other countries to take advantage of multiple growing seasons. Given our reliance on horticultural imports, we have a robust inspection system to make sure the foods, plants, and seeds we receive from countries like China are indeed safe. 

To wrap this mystery up –

While there’s not much you can do now that you have these mystery seeds, enjoy the fun of trying something unexpected. If you ended up with a pepper that you don’t like or can’t eat (like the Hot Wax for Purple Bell switch), share with friends or donate to a local food pantry. After all, you can’t tell that the jalapeño isn’t green when it’s turned into a jalapeño popper.

Sources

https://www.fas.usda.gov/data/record-us-fy-2022-agricultural-exports-china

Po-TAY-to, po-TAH-to: Let’s call the whole yam thing off!

As most folks in the US prepare for a Thanksgiving meal, or at least eat more Thanksgiving-inspired fall meals, potatoes and sweet potatoes often play a major supporting role in these most delicious victuals.  Whether mashed, smashed, baked, candied, or turned into casseroles or pies, these starchy vegetables are stockpiled in grocery stores and markets in the fall for shoppers to turn into those tasty treats. 

But sometimes there is confusion lurking in those grocery aisles and even in the minds of unwary shoppers….enter the “yam”.  Wander down the canned vegetable aisle and you’ll see canned yams.  Are they the same thing as sweet potatoes?  And are they related to the standard potato that you usually mash, bake, or fry?  I yam going to set the set the record straight. 

First things first, sweet potatoes and yams are two totally different species so they are not the same thing.  They’re even in different plant families so they aren’t even closely related.  And neither of them are related to the regular old potato.  So those “canned yams” at the grocery store are mis-named.  They are sweet potatoes.  Yams are rarely consumed or sold in the US, except usually though markets that sell specifically African/Caribbean foods. 

A sweet potato in bloom….look familiar?

Sweet potatoes are soft when cooked, thin/soft skinned, usually pretty sweet, and usually orange.  Though there are some white-fleshed, less sweet varieties available.  Native to tropical regions of the Americas sweet potatoes, or Ipomoea batatas, are members of the Convolvulaceae, or bindweed, family and are closely related to morning glories many of which are in the same genus Ipomoea.  These sweet veggies are part of the root structure, so they are modified storage roots that store starches and sugars produced by the plant. 

Yams, on the other hand, are white with a hard skin like tree bark, and are usually pretty dry when cooked.  There are three main species of yams in the Dioscorea genus, which has its own family Discoreacea.  Also tropical in nature, three different species were domesticated independently in Africa (D. rotundata), Asia (D. alata), and the Americas (D. trifida).   Yams are monocots, meaning they are more closely related to lilies and onions than they are to sweet potatoes.  Also, unlike sweet potatoes, the edible portion of a yam is a tuber, which is structure arising from modified stem tissue. 

Piles of yams…that look nothing like sweet potatoes

And just to round out the tater trifecta – the humble potato.  Sometimes called a white potato or an Irish potato (which are both bad descriptors for them because they come in many different colors, and while they are a staple in Ireland they originate from the Americas), these versatile spuds, Solaunum tuberosum, are members of the Solanaceae family and are closely related to tomatoes, Solanum lycopersicum.  Their morphology has similarities to those of the yam, though, as they are tubers arising from the stem vs being a root like sweet potatoes. 

So where does all the confusion come from? 

There are various theories on how yams and sweet potatoes got caught up in this mash-up, and I don’t pretend to be an expert here.  But the most common theory that I’ve seen is that enslaved African people held in the US south called the local sweet potatoes by the names they used for yams, as the sweet potatoes reminded them of the yam that was part of the staple diet in many African countries.  The word yam is derived from nyam, nyami, or nyambi, meaning “to taste” or “to eat” in certain African language dialects.  Adding to the story, apparently Louisiana sweet potato growers in the 1930s used “yams” as a marketing name for a new orange-fleshed sweet potato cultivar and the name stuck. 

One thing I find interesting is that yam was used to describe orange sweet potatoes when the white fleshed ones (which are less common now) would probably more resemble an actual yam, both in appearance and flavor.  In fact, in my travels in Rwanda I ate many white fleshed sweet potatoes, as they are now a major staple crop in many African countries.  It is also interesting to note that the refugee farmers in our urban farm programs prefer to grow the starchier, less sweet varieties of sweet potatoes, which often complicates things as they can be hard (and expensive) to find. 

Whether you cook sweet potatoes or “white” potatoes for your Thanksgiving feast, now you’ll know a little bit about how each of those crops are different…and you’ll at least know that sweet potatoes aren’t yams. 

Barf! An ode to the fascinating life of slime mold

It may seem odd to sing the praises of a weird, sometimes gross, looking phenomenon that sometimes freaks gardeners out, but every summer I love educating gardeners about the fascinating lives of slime molds. Here in Nebraska we often get calls about “this weird thing that’s all over my mulch” after a rainy period in the summer and whether or not it will 1) hurt their plants, 2) poison them, or 3) some other horrible outcome they’ve dreamed up. But the fact is, not only are slime molds harmless they’re also quite fascinating. In fact, I’ve often thought if I ever had the right terrarium setup, I’d love to have a pet slime mold. No joke.

What is a slime mold?

Basically speaking, slime molds are a group of eukaryotic organisms similar to amoebae that feed on microorganisms and do some pretty amazing things for simple-celled organisms. They can often be found in soils, forests, especially wetter ones, where they live on the microorganisms that are breaking down fallen logs and detritus on the forest floor. In gardens, you’ll find them in areas with heavy, woody mulches or high organic matter. (They also live in rain gutters if they’re full of leaves and also air conditioner units with poor drainage, FYI.) Most of the calls that we receive at the extension office are from suddenly finding slime mold in woodchip mulch. Usually after a large or extended rain event during the summer, and usually in thickly layered (several inches) mulch.

When food (microorganisms) is abundant, the majority of a slime molds, at least the ones in the “cellular slime mold” category live most of their lifecycle is as a single cell, imperceptible to humans. But when food becomes scarce is when the fun begins. In mulch, this can happen when the weather conditions (wet and hot) favor a slime mold population boom thanks to sexual reproduction and they eat themselves out of house and home. When that happens, the individual cells join together as a single body (one big cell blob with multiple nuclei), forming a visible and for many disconcerting presence in the landscape. Many of them look like actual slime and several look like webbed networks or neural structures.

Slime mold on mulch | Jody Green, UNL Extension @JodyBugsMeUNL

The most fun thing about slime mold, though, and the thing that I love about them is that THEY MOVE! Yep, you heard that right. These single-celled organisms, that stream together to form a single body, can chemically sense the presence of food in the nearby environment and will change shape (together) to move toward the food. And they’ll follow the food wherever it is – on the ground, up on a plant, into the canopy of a tree, etc. Scientists have demonstrated this by having slime molds solve mazes or even create designs, like the Tokyo subway system, in vitro. The trail of slime that it leaves in its path even relays a chemical signal that it uses to “remember” where it has been so it doesn’t backtrack or go the wrong direction.

Several of our concerned callers call because a slime mold has moved up onto one of their plants and they want to know if 1) it will kill their plant and 2) if it is toxic. Neither of which is the case. But most of our calls happen when our most common slime mold in the area moves onto its next phase of life – spore production.

You see, when environmental conditions change or the slime mold finds a good supply of food it is time to settle down for some good old-fashioned asexual reproduction. The shape and texture of the slime mold changes, usually becoming more pronounced and dryer looking as it produces sporangia that produces spores.

Slime mold life cycle | Wikimedia Commons

Callers often describe what looks like dog vomit in their landscape, and that’s where our common slime mold gets its name – the Dog Vomit Slime Mold (Fuligo septica).

Dog vomit slime mold | Peter Stevens, Flickr

Shortly after this phase, the collective body of the slime mold will dissipate. Spores will turn into new single-celled organisms that will repeat the process over again.

Can it be stopped or controlled?

First of all, why would you want to stop this fascinating phenomenon in your garden? (I’m kidding). Really, there’s nothing you can do as a control and there really isn’t a need to do so. As I stated earlier, slime molds do no harm to plants and aren’t dangerous for people or pets. If you just don’t like the look of it, you can reduce the likelihood of it popping up in your landscape by reducing the thickness of woodchip mulch (don’t let my GP colleague Linda hear me say that) or reduce irrigation if it is occurring outside of larger rain events.

Otherwise, just enjoy your pet! It won’t hang around for long. The visible, fascinating life of a slime mold is fleeting but exciting. Next time you see a slime mold, check it out! And keep an eye on it to see if it moves or if it progresses through its life cycle – maybe you’ll just develop an appreciation for them, too. And I’m not joking about pet slime molds, someone even wrote a guide to dog vomit slime mold pet care!

Hydroponics for the Holidays? Home Systems are a hot holiday gift list item

Systems to grow fresh produce in your home using hydroponics or other automatic processes have been popular for several years but seem to be even more popular this year with more folks home and looking for something to do and hoping to produce their own food.  As a result, these systems are popping up on holiday wish lists and gift buying guides all over the internet.  But are they worth it?  And if so, what should you look for in a system? 

First off, what are these systems? And what is hydroponics?  Hydroponics is the process of growing plants without soil in a aqueous nutrient solution.  Basically, you provide all the nutritional needs of the plants through nutrient fertilizers dissolved in water.  These systems can grow plants faster and in a smaller space than traditional soil-based production. It also allows you to grow plants indoors and in areas where you would not normally be able to grow.

This Aerogarden (which is the previous generation) has a digital brain that controls light and water schedules for the specific growth phase of the plant and yells at you when it thinks you need to add more fertilizer solution.

As for systems, you might have seen what is probably the “oldest” one on the market – the AeroGarden.  Since it is the oldest and most common, that’s the example we’ll be staying with.  It has been around a few decades and has evolved from a basic electronic system to fully automatic, “smart”Bluetooth connected systems that you can control with your phone.  In recent years there have been many new systems come onto the market at all different sizes and price points.  A quick search of online retailers will usually provide an array of options – from DIY kits to plug-and-play enclosed systems such as “Click & Grow” and “Gardyn”. My only experience is with the Aerogarden system, so I can’t speak to any of the others (though I’d love to try them out!).

The answer to “are they worth it” is up to you, really.  Most home based hydroponic or aeroponic systems offer convenience, but at a cost.  Most cost several hundred dollars and are small, so they produce a small amount of produce (or other plants) at any one time. So you have to determine what goals you, or your intended giftee, have with the system. 

“Baby” lettuce, 18 days after sowing. The current version of this 9-plant Aerogarden system, called the “Bounty”, retails for $300 but you can usually get it for under $200 on sale.

The benefit of the “plug-and-play” enclosed systems like the AeroGarden is that basically you can take it out of the box, set it up in less than 10 minutes, and have some fresh lettuce or herbs in a few weeks.  It controls the water cycles, lighting, and all other conditions for growth.  You just drop in pods that contain the seeds suspended in a spongy-material.  The smallest system, that holds 3 plants, retails for $100.  As an additional expense comes from buying refill kits to replant. The mid-size systems are the most common and range from $150-$300.  The largest system, the “XL Farm” retails for $600. But these systems are commonly on sale at pretty significant discounts. 

For many systems, you typically buy a new set of pods (there are different plant variety selections), but there are pods you can buy to assemble your own using your own seeds.  For the AeroGarden, the pod kits range from $15 up to $30 to grow up to 9 individual plants. There are other plug-and-play systems on the market, as well as some kits that are more build-your-own and less automated. 

No matter which systems you buy (or gift), keeping these costs in mind is important.  If you’re looking for a fun and easy activity with the benefit of a little fresh produce and aren’t as concerned with production costs these systems may be for you – and if you are giving or getting them as a gift that definitely makes it more economical. But given the cost of the plug-and-play systems and the refill pods, they will never be an “economical” option for producing your own food.  If you are wanting to produce food on a budget and you’re interested in home hydroponics, look for plans to build your own or buy a DIY kit. 

A Cactus by Any Other Name: A Case of Mistaken Holiday Cactus Identity

Believe it or not, a cactus, of all things, is one of those plants that have come to represent the holidays and feature in the regular rotation of holiday houseplants. Then again, maybe it isn’t so strange amongst its peers that feature a flashy bulb-grown plant named for a horse’s head (the Latin name of amaryllis is Hippeastrum, literally meaning horse flower), a plant that has ugly flowers but brightly colored leaf bracts and leaks sticky and irritating latex when damaged, or some daffodil-like flowers that have musky odor so strong it makes some people nauseous.  But…..I digress. 

Back to the cactus.  However you see it though, the cacti that make their debut at the holidays are suffering under a case of mistaken identity.  What you typically buy as a Christmas cactus is not a Christmas cactus at all. It is actually a Thanksgiving cactus.  Now this wouldn’t be such a big deal, except that there is such a thing as a “Christmas cactus” — but you won’t find one on store shelves. Nay, it is hard to even find one in garden catalogs.  And this is sad, because the Christmas cactus is, I think, even more beautiful than the Thanksgiving cactus. 

How did we end up ignoring the beautiful Christmas cactus in favor of its holiday cousin?  It all comes down to timing and how we buy things for the holidays.  It seems that, as the shopping and holiday seasons creep ever upward on the calendar, retailers have little love for a cactus that is actually programmed to bloom at Christmas. They need something that blooms earlier so that it can be on the store shelves as early as possible. (At this pace, breeders will need to develop and Independence Day cactus for the Christmas shopping season.)

Therefore, the Thanksgiving cactus has been rebranded as a impostor stand-in for the true Christmas cactus. We won’t even talk about the Easter cactus, which just totally feels left out of the family (and yes, there is such a thing and it is beautiful).

These cacti were in cultivation in Europe by 1818 and various different species were being hybridized, probably most notably by W. Buckley.  The most notable hybrid, bred now named Schlumbergera ‘Buckleyi’ is considered to be the first actual “Christmas cactus” and associated S. x buckleyi hybrids are still grown as Christmas cacti.  Cultivars and crosses of S. truncata are the Thanksgiving cacti that have been rebranded as Christmas cacti.  They can be identified by their flattened stems (or cladodes or cladophylls) that have spiky, toothed edges and zygomorphic (now that’s a fancy word — it means that they have a two-sided, or bilateral, symmetry) flowers.  Most of the Thanksgiving cacti that have these characteristics.

W. Fitch (drew), Swan (engraved) – Bot. Mag. 66. 3717, as Epiphyllum russellianum Source: Wikimedia commons

You’ll most commonly find them in pink colors, but you can now find them in yellowish colors. The flower shape often leads to its nickname: “Zygo cactus.”

S. x buckleyi are the true Christmas cacti and form what is called the Buckleyi group.  Most of these have characteristics that come from the species S. russelliana, which was used in the early Buckley crosses. They can be identified by their rounded, less pointy cladodes and round, radially symmetrical flowers. They do have a similar growing form, but those in the know can tell the difference.

And for those following along at home, the Easter (or spring) cactus used to be considered part of the Schlumbergera genus (S. gaertneri) and then the Rhipsalidopsis genus, but now is classified as Hatiora gaertneri has radially symmetrical flowers but the cladodes are three dimensional rather than flat, elongated, and scalloped.  They have a wide range of colors, such as red, pink, and even orange.

Holiday cactus care

It’s a cactus, so it should be easy to care for – I just water it sparingly and keep it dry, right?  WRONG!

Whether you have a Thanksgiving or Christmas cactus (or an Easter one, for that matter), you take care of them the same way. Keys to their care come from their native habitat, which is not a desert but the cloud forests of costal south-east Brazil.  The high-altitude costal areas where they’re from are cool, shaded, and relatively humid with the mists and moisture rich air. They are epiphytic or lithophytic – meaning that they grow on trees and in crevices with decaying plant material rather than in the soil.  And while you don’t need to know this to grow them, the morphology of the flowers have developed to support the feeding of hummingbirds which act as their main pollinator.

Since we don’t grow them epiphytically, when we pot them we need to make sure that we provide a light substrate for them to grow and to get plenty of oxygen to the roots. Potting mixes should have a high ratio of peat or coir and even some bark or other coarse woody material.  As for watering, you’ll want to keep the soil fairly moist, rather than dry.  You’ll also want to let them dry slightly between watering, but don’t think that they like to live the life of dehydration — you do need to keep them watered.

One of the reasons that they bloom at very specific time of year has to do with light and, to a lesser extent, temperature.  They are short-day (or rather  long-night) plants, so they flower as days grow shorter (or longer, in the case of the Easter cactus) and nights grow longer.  The Thanksgiving cactus will bloom with just a little shorter dark period than the Christmas cactus, which is why it blooms in late fall as opposed to the Christmas cactus that blooms closer to when days are the shortest around the solstice.  They will also bloom better and longer if they have cooler temperatures, so keeping them in a cool area of the house is ideal.  In high light situations the cladodes will turn red.  Keeping them too dark, however, will limit growth and keep them from thriving.

Since they are short-day plants, the plants need a period of several weeks where the period of darkness at night is 12 hours or longer for their flowers to begin forming.  This occurs naturally about mid-October, but you can delay flowering by using grow lights to lengthen the day (or keep in mind that bright indoor lights can also limit or reduce blooming).  Also, don’t be alarmed if they bloom at odd times through the year.  Since daylight coming into your windows can be altered by window treatments or films, the light levels can technically be “just right” for flowering at multiple times per year.  In my old office the tint on the windows created the right conditions at least once or twice per year – one year I had a Halloween cactus and the next it was a Memorial Day cactus. 

If your cactus does not flower, you need to move it to a spot where it gets at least 12 hours of relative darkness to initiate blooms (keep away from indoor light sources or windows near outdoor lights). Hopefully, you’ll have lots of colorful blooms for Christmas…..or whichever holiday your cactus celebrates. 

Sources

Is it a Thanksgiving, Christmas, or Easter Cactus? https://www.extension.iastate.edu/linn/news/it-thanksgiving-christmas-or-easter-cactus

McMillan, A. J. S.; Horobin, J. F. (1995), Christmas Cacti: The Genus Schlumbergera and Its Hybrids (p/b ed.), Sherbourne, Dorset, UK: David Hunt

The Myth, the Legend, the Parasite: Romance, Lore, and Science beneath the Mistletoe

As we hurdle ever closer to the holidays and the end of the year, there’s lots of plants we could talk about – amaryllis, poinsettias (and the abuse thereof with glitter and paint), whether or not your cactus celebrates Thanksgiving, Christmas, Easter or is agnostic, and on and on.  Each of these plants have an interesting history and connection to the holidays, but today we’re going to be a little more naughty…but nice.  We’re going to talk about mistletoe.

Now, mistletoe is one of those holiday plants that you don’t really want growing in your own garden. That’s because, even though it is a symbol of love and even peace, it truly is a parasite … and poisonous. It has been celebrated and even worshipped for centuries, and still has a “naughty but nice” place in holiday celebrations.

Burl Ives, as the loveable, banjo-playing, umbrella-toting and story-narrating snowman in the classic “Rudolph the Red-Nosed Reindeer” claymation cartoon tells us that one of the secrets to a “Holly Jolly Christmas” is the “mistletoe hung where you can see.” But where does this tradition of giving someone an innocent (or not-so-innocent) peck on the cheek whenever you find yourselves beneath the mistletoe come from? And just what is mistletoe anyway?

While mistletoe specialists need mistletoe, the reverse does not hold—mistletoe in many regions is dispersed solely by dietary generalists.
Distribution of mistletoe (and mistletoe specialist birds). Source: Mistletoe Seed Dispersal. Watson, D.M.

There are around 1500 species of mistletoe around the world, mainly in tropical and warmer climates, distributed on every continent except Antarctica.  In North America, the majority of mistletoe grows in the warmer southern states and Mexico, but some species can be found in the northern US and Canada.  A wide variety of birds feed on the berries of mistletoe and thus disperse seeds.  These birds include generalists who opportunistically feed on mistletoe, and specialists who rely on the berries as a major food source.

Mistletoe Haustoria from from Julius Sachs’ 1887 Lectures on Plant Physiology. Source: The Mistletoe Pages

First, we’ll cover the not-so-romantic bits of this little plant.  Mistletoe is a parasitic plant that grows in a variety of tree species by sinking root-like structures called haustoria into the branches of its host trees to obtain nutrients and nourishment. It provides nothing in return to the tree, which is why it is considered a parasite.

 

A heavy mistletoe infestation.                        Source: Pixabay

Mistletoe grows and spreads relatively slowly, so it typically does not pose an immediate risk to most trees.  While a few small colonies of mistletoe may not cause problems, trees with heavy infestations of mistletoe could have reduced vigor, stunting, or susceptibility to other issues like disease, drought, and heat. So be on the lookout for mistletoe in your trees and monitor it’s progression.

This little plant does have a long and storied history — from Norse mythology, to the Druids, and then finally European Christmas celebrations. Perhaps one of the most interesting things about the plant is the name. While there are varying sources for the name, the most generally accepted (and funniest) origin is German “mist” (dung) and “tang” (branch). A rough translation, then, would be “poop on a stick,” which comes from the fact that the plants are spread from tree to tree through seeds in bird droppings.

“Baldur’s Death” by Christoffer Wilhelm Eckersberg (1817)

In Norse mythology, the goddess Frigga (or Fricka for fans of Wagner’s operas) was an overprotective mother who made every object on Earth promise not to hurt her son, Baldr. She, of course, overlooked mistletoe because it was too small and young to do any harm. Finding this out, the trickster god Loki made a spear from mistletoe and gave it to Baldr’s blind brother Hod and tricked him into throwing it at Baldr (it was apparently a pastime to bounce objects off of Baldr, since he couldn’t be hurt).

Baldr, of course, died and Frigga was devastated. The white berries of the mistletoe are said to represent her tears, and as a memorial to her son she declared that the plant should represent love and that no harm should befall anyone standing beneath its branches.

The ancient Druids also held mistletoe in high esteem, so high that it could almost be called worship. During winter solstice celebrations, the Druids would harvest mistletoe from oak trees (which is rare — oak is not a common tree to see mistletoe in) using a golden sickle. The sprigs of mistletoe, which were not allowed to touch the ground, would then be distributed for people to hang above their doorways to ward off evil spirits.

While the collecting and displaying of mistletoe was likely incorporated into celebrations when Christmas became widespread in Europe in the third century, we don’t really see mention of it used specifically as a Christmas decoration until the 17th century. Custom dictates that mistletoe be hung in the home on Christmas Eve to protect the home, where it can stay until the next Christmas Eve or be removed on Candlemas (which is Feb. 2). The custom of kissing beneath the parasitic plant isn’t seen as part of the celebration until a century later.

Washington Irving, who more or less reinvigorated the celebration of Christmas in the United States in his day and whose writings still define the idyllic American Christmas celebration, reminisced quite humorously about mistletoe and Christmas from his travels to England. He wrote:

“Here were kept up the old games … [and] the Yule log and Christmas candle were regularly burnt, and the mistletoe with its white berries hung up, to the imminent peril of all the pretty housemaids.”

Whether or not your housemaids will be in peril, the hanging of the mistletoe can be a fun Christmas tradition. Look for it at garden centers and Christmas tree lots this season.  Or maybe you can find some growing wild and harvest it for your own decor. However, I would recommend not getting it out of the trees the “old Southern way” — shooting it out with a shotgun.

Sources:

  • Tainter, F.H. (2002). What Does Mistletoe Have To Do With Christmas?  APSnet Features. Online. doi: 10.1094/APSnetFeature-2002-1202
  • Briggs, J. (2000). What is Mistletoe? The Mistletoe Pages – Biology. Online. http://mistletoe.org.uk/homewp/
  • Watson, DM. (n.d.) (accessed). Mistletoe Seed Disperal [Blog Post]. Retrieved from https://ecosystemunraveller.com/connectivity/ecology-of-parasitic-plants/mistletoe-seed-dispersal/
  • Norse Mythology for Smart People. (nd) The Death of Baldur. Retrieved from https://norse-mythology.org/tales/the-death-of-baldur/

 

Grow Garlic – Keep the Neighborhood Vampires at Bay

While most of those gardening tasks are coming to an end, in most parts of the US it’s time to think about planting a few things in the veggie garden to bring a flavorful bounty next year – garlic (and a few related alliums).

I often reference Halloween and vampires when I talk about garlic, not just because traditional lore says that garlic repels vampires, but because it is a good reminder of when to plant garlic in the garden. October is the prime time for adding the alluring allium to the garden. You can also remember that you plant garlic during the same period that you plant spring flowering bulbs.

Why do vampires hate garlic?

Yes.  Vampires are fictional (unless someone finds some empirical evidence of their existence, since you can’t prove a negative 😉 ).  These bloodsucking creatures of folklore may actually have a basis in fact that could explain their aversion to garlic. Way back when people didn’t have science to understand things, they often invented explanation for things that were supernatural.  Sometimes these explanations may have actually had some truth to them.

In this case, the symptoms of vampiricism could have evolved from the symptoms of porphyria – a set of rare disorders of hemoglobin (there’s the connection between vampires and blood).  Symptoms of porphyria include shrunken gums (that could make teeth look like long fangs), painful sensitivity to sunlight, and….and averse reaction to garlic. The reaction comes from the effect of garlic on the blood – it can stimulate red blood cell turn over and increase blood flow, both of which can exacerbate symptoms of porphyria and cause acute, painful attacks.  There’s also an allegorical connection – vampirism was considered a disease (or represented the spread of disease in some literary cases) that was spread by a causal agent and garlic was seen as a curative for disease (it does have some antibacterial properties).  Note: other possible symptoms of porphyria can be excessive hair growth in random areas of the body, which gives it a connection to lore around lycanthropy.

On to the gardening

Now that we’ve covered some trivial, albeit interesting, info lets get on with the gardening!

While many people are accustomed to the single variety available in grocery stores, there are several different types of garlic that all have different flavor characteristics. These types can be classed in two categories; hardneck garlic has a hardened central stem when it dries, and softneck garlics remain soft and pliable. Softneck varieties are the ones that lend themselves to being braided into those hanging garlic braids. Softneck varieties are also longer-storing than hardneck varieties.

It can be tough to find garlic in local garden centers to plant. Those that do carry garlic, often carry it at the wrong time of year for planting when it is shipped in on the spring garden displays. If you don’t have friends to share their garlic with you, or a local farmer to buy some from, you are going to have to go the mail order (or online order) route.

Once you have your garlic bulbs, split them up into cloves, being sure that you have a piece of the basal plate (the part that holds them all together) on the clove. This one clove will turn into a whole bulb over the growing season.

Plant the cloves tip up about 4 to 6 inches apart and about 2 inches deep in loose, organic soil. Mulch after planting with about one inch of straw or shredded newspaper.

Garlic is a relatively heavy feeder, so it would benefit from a good balanced fertilizer treatment with nitrogen after it is established. You can also plant them in the garden where you grew beans over the summer – the bacteria that colonized bean roots adds nitrogen to the soil.

After that, just be patient. It may pop up before winter if the weather is mild, but don’t worry – it can survive even if a freeze kills the growth back to the ground.  Garlic requires little maintenance, and only requires water if the weather turns very dry. Harvest it once the leaves start to die in mid-summer (around July, unless it is an early-maturing variety). Be sure to save some to plant next year and store the rest for use in the kitchen.

Aside from garlic, there are some other odoriferous onion relatives you can plant this time of year like shallots and perennial onions in the vegetable garden or edible landscape.

Shallots have a mild onion flavor and are great because they form cloves like garlic (meaning you don’t have to cut up a whole bulb if you just need a little bit) and store well. The beauty of shallots is that they can also be planted in really early spring — they are a multi-seasonal crop. You can also start them from seeds in the spring.

Shallots are technically perennials, as they will grow over many years if left undisturbed. However, to harvest them, you have to dig them up so they are usually grown as annuals. Once you dig them up, use the larger bulbs for cooking and save the smaller ones for replanting.

Multiplier onions, sometimes called “potato onions” are another fall-planted perennial. These plants produce clusters of bulbs (hence the name “multiplier”) that are harvested in the early summer for bulb onions.

One of the benefits of these and other perennial onions is that you can harvest the green blades of the plant for use as green onions or scallions throughout most of the winter and spring.

Egyptian walking onions are another perennial that can be harvested either for its bulb or as a green onion. The name comes from the bulbils that form at the top of the flower stalk. When they mature, they get heavy enough for the stalk to collapse and fall over, creating a new bunch of onions away from the mother plant. You can allow them to do this to fill in an area, though most people limit it by harvesting the bulbils before they fall.

There are also perennial leeks that have a flavor similar to leeks and can be harvested as green leeks through the winter or dug up as small, tender leeks in the spring.

If you love growing perennial vegetables that add flavor to just about any dish, give these tasty plants a try. They’re really simple to grow and can keep your garden and your kitchen full of fun and flavors for years to come.

A quick primer on types of garlic

Hardneck Varieties

  • Purple Stripe — bulbs have purple on the outside. Some of the tastier garlics that become deliciously sweet when roasted.
  • Porcelain — popular gourmet variety. Usually has a more robust and spicy flavor. Bulbs are typically large and have large cloves.
  • Rocambole — Rich, complex flavors popular with chefs. Their scapes (edible blooms) form a double loop. They do not do well where winters are warm.
  • Asiatic/Turban — Do not store for long periods. Mature earlier in the season (late spring as opposed to summer) than other types. Flavors are usually strong and hot.
  • Creole — Attractive red color. Performs well where winters are warmer. The flavor is similar to (though milder than) Asiatic/Turban Varieties.

Softneck Varieties

  • Artichoke — the grocery store garlic (California White) is an artichoke garlic, though other varieties have more complex flavors. Bulbs tend to have multiple layers of cloves.
  • Silverskin — often the last in the season to mature, these are the longest-storing garlics.

Elephant Garlic

This is a common “garlic” planted by many gardeners because it has large, easy to use bulbs with a garlicky flavor.  Though it is technically not a garlic species – it is a type of perennial leek.

Our New Year’s Resolution – to keep you informed and entertained every week.

Happy New Year!

The Garden Professor’s collective resolution is to have at least one new blog post a week for 2018. So I’m kicking things off with a little fact checking on the claims made for a product that’s “a complete ecosystem in a bottle.” The company touts its strong connection to science (“our products revolve around biology”). There is a long list of ingredients and claims – way too much for one post. We’ll start with the first four this week.

All this can be yours if the price is right!

Ingredient claim #1: “Chitin/chitin degrading Bacillus: Chitin is a natural polymer that is found in crustaceans, such as crabs, lobsters, shrimp and oysters as well as other organisms, such as insects, worms and fungi. When added to the soil ecosystem, chitin (also referred to as chitosan) promotes the growth of chitin-degrading bacteria. These bacteria, in turn, create a hostile environment for pathogenic fungi and parasitic nematodes. Chitin also acts directly on plants to promote tissue repair and disease resistance.”

Fact check #1: A couple of technical points: oysters don’t have chitin. And they’re not crustaceans. They are MOLLUSKS. They have shells with CALCIUM. And chitosan is not the same thing as chitin. It’s an industrially produced material that comes from chitin.

Not a crustacean.

Chitin is indeed found in arthropods, which include crustaceans and insects. Now, most of us don’t have crabs, lobsters and shrimp roaming our landscape, but we do have insects. Lots of them. They produce a lot of chitin when they molt and when they die. Do you really think we need to add more chitin for Bacillus to consumer? I sure haven’t seen any science supporting that practice.

What about the Bacillus species that degrade chitin? Well, if you’ve got insects in your landscape, you can bet you’ve got microbes that break down chitin as well. Otherwise you’d be up to your garden boots in chitin carcasses. So why do we need to add more bacteria?

Imagine billions of these in your garden…

Finally, there’s no evidence that chitin applied to plants in the landscape has any effect whatsoever. You might get responses in the lab, and chitosan (not chitin) might have some direct application. But like many other elicitors, you have to get it inside the plant to have a cellular effect. And plants are particularly adept at keeping things like decomposing bug bits outside of their tissues.

Ingredient claim #2: “Compost tea: The disease suppressive characteristics of compost have long been known and therefore the liquid extracts from compost, known as compost teas are being use to battle plant disease while stimulating plant growth. Beneficial organisms including bacteria (primarily from the genera Bacillus, Pseudomonas, and Penicillium) along with some yeast and fungi form a physical barrier against disease causing agents and provide a competitive environment in which the pathogenic species lose out. In addition, compost teas stimulate plant growth, translating into a healthier plant, which is more resistant to attack from disease. Compost teas have shown effectiveness in the control of late blight, grey mold, downy and powdery mildew, fusarium wilt, and apple scab among many others.”

The visuals are more interesting than the product.

Fact check #2. Just because compost has disease suppressing characteristics doesn’t mean that water leaching through it will have the same. We’ve been hearing for years that compost tea suppresses disease. Where’s the definitive research? It’s a topic I’ve been following for nearly two decades and there’s still nothing that’s consistently effective. (Another technical point here: it’s illegal to make pesticidal claims of a product that’s not registered for that use. Company lawyers may want to review that.)

There are many species of bacteria, including the ones mentioned, that form protective and beneficial biofilms on plant tissues such as fine roots. You can find these bacteria in compost and other sources of organic material – that’s their food source. You won’t find many of them in compost tea.

I’d love to see evidence of anything stimulating plant growth other than plant growth regulators (or hormones as they’re sometimes called).

Aren’t marketers getting tired of compost teas yet? I’m getting tired of hearing about them. I reviewed the science about them 10 years ago and haven’t seen anything to warrant an update.

Ingredient claim #3: “Essential oils: or essences they are called, are highly concentrated substances extracted from various parts of aromatic plants and trees. Essential oils are combined with other carrier oils and teas for stabilization. Essential oils are used against plant pests and disease by interfering with their reproduction and feeding habits while protecting beneficial predatory organisms.”

We like them, ergo they work.

Fact check #3: Essential oils have no documented benefit when applied outdoors. They can be effective in closed spaces, like homes and greenhouses, but they dissipate quickly outside. What I really want to see, however, is the mechanism by which oils can identify – and actually protect! – beneficial insects while killing pests. (Hey, lawyers…we’ve got another pesticidal claim here…)

Ingredient claim #4: “Streptomyces griseoviridis: Is a naturally occurring soil bacteria. The microbe deprives pathogenic fungi of living space and nourishment by colonizing roots in advance of fungi. In addition the microbe secretes various enzymes and metabolites which inhibit pathogenic growth. Streptomyces griseoviridis has been shown to promote the growth and yield of all plants. Streptomyces griseoviridis is used for the prevention of root and stem rot, Pythium, Rhizoctonia, Helminthosporium, Sclerotinia, among others.”

All those stickers keep the bad guys from colonizing.

Fact check #4: While this is a naturally occurring soil bacterium, it’s not clear where it naturally occurs. EPA information states it was first isolated in Finland from peat bogs. Is this something we should be introducing to our own soils? Its effectiveness in disease control and plant performance is sporadic and confined primarily to greenhouse application on crop plants. The diseases listed are common in greenhouses, but not necessarily in gardens and landscapes (presumably because there are natural controls outdoors in healthy soils). There is certainly nothing to support its use in gardens and landscapes, especially considering that many native, beneficial bacterial species can colonize plant roots and act as a protective biofilm.

Stay tuned for next time!

Love notes of genetics and physiology for Valentine’s Day

A St. Valentine meme compliments of my "friend" the self-styled Rev. Apostle, and Bishop to the Stars, Joel L. Watts.
A St. Valentine meme compliments of my “friend” the self-styled Rev. Apostle, and Bishop to the Stars, Joel L. Watts.

Ahhh….’Tis the time of year when we celebrate romantic love in homage to a 3rd Century priest who came up a head short for performing unsanctioned Christian weddings.  (It is also of note that St. Valentine, or Valentinius as his friends called him, is the patron saint of bee keepers but, strangely, not of birds, flowers, or trees).

In celebration, many suitors, partners, spouses, fling-seekers, and woo-wishers will flock to florists, grocery floral counters, and even gas stations to purchase flowers, namely roses, that have likewise been beheaded.

Those roses, with all of their tightly wound petals, look nothing wild-type roses. Modern roses are the product of many centuries of breeding that started independently in China and the Mediterranean region.

So if the wild-type rose has a single row of five petals, how do breeders get all of those extra petals?  They can just come from nowhere, you know.

The simple answer is that tissue that turns into stamens in the wild-type flower are converted to petal tissue.  While early (and even contemporary) plant breeders may not understand the mechanism responsible for the doubling (gene expression), research is showing that the same gene is responsible for the doubling in both the Chinese and Mediterranean set of species/subspecies.

In a nutshell, what happens is that the different regions of the flower – sepals, petals, stamens, carpel – develop in response to the expression of a set of genes.  It isn’t just the genes acting alone, though; it is their interaction in the tissues that makes the difference.  These genes are grouped by the floral part they affect and are grouped as A-Function, B-Function, C-Function, and E-Function.

If you want to learn a whole lot more about it than I can ‘splain (it has been a few years since my last plant physiology class), this paper thoroughly explains the gene expression and evolution of the flower.  Their figure depicting the flower model is informative, yet simple.  I’ve included it (and its accompanying caption) below.

The ABCE model of floral organ identity. Sepals are produced where A function acts alone, petals where A and B functions overlap, stamens where B and C functions combine, and carpels where C function acts alone. In the eudicot genetic model Arabidopsis thaliana, APETALA1 (AP1) and APETALA2 (AP2) are the A-function genes, APETALA3 (AP3) and PISTILLATA (PI) together specify B function, C function is specified by AGAMOUS (AG), and multiple SEPALLATA genes provide E function
The ABCE model of floral organ identity. Sepals are produced where A function acts alone, petals where A and B functions overlap, stamens where B and C functions combine, and carpels where C function acts alone. In the eudicot genetic model Arabidopsis thaliana, APETALA1 (AP1) and APETALA2 (AP2) are the A-function genes, APETALA3 (AP3) and PISTILLATA (PI) together specify B function, C function is specified by AGAMOUS (AG), and multiple SEPALLATA genes provide E function.  http://www.pnas.org/content/107/52/22570

 

In the paper “Tinkering with the C-Function: A Molecular Frame for the Selection of Double Flowers in Cultivated Roses” researchers show that in lines from both regions of the world produced double flowers as a result in a reduction of expression of the C-Function gene AGAMOUS (RhAG) leads to double flowers.  In Arabidopsis (every plant lab bench jockey’s favorite model plant), this reduction shifts expression of the A-Function genes toward the center of the plant, turning stamens into petals and carpels into sepals.

Now, one question I get from time to time is “why don’t these roses smell like the old-fashioned roses?”  One answer is that as we breed for looks, we are breeding out genes responsible for scent oil production.  So Shakespeare was actually wrong when he said that “a rose by any other name would smell as sweet.”  That isn’t true these days.

So, I wish you a perfectly lovely Valentine’s Day, no matter how you celebrate. Just remember to whisper sweet nothings of floral gene expressions in your sweetheart’s ear.  And remember to stop and smell the roses – if it is a variety that has a decent scent.