Here’s the trunk of a Japanese maple I photographed last month at a big box store in Seattle:
Why does the trunk look like this? Answers and more photos on Monday!
Author: Linda Chalker-Scott
Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and a Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets.
Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019).
In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award.
"The Garden Professors" Facebook page - www.facebook.com/TheGardenProfessors
"The Garden Professors" Facebook group - www.facebook.com/groups/GardenProfessors
Books: http://www.sustainablelandscapesandgardens.com
Potted plants…really potted
A week or so ago my new friend Doug wondered about some gardening advice on the radio: would adding vodka to paperwhite narcissus make the flowers less “floppy?” The explanation he’d heard was that alcohol would burn the roots and reduce stem growth. Then today I received an email newsletter with the same intriguing information. This newsletter referred to a 2006 article that appeared in HortTechnology as the source of this information.
The study by Miller and Finan has generated a lot of interest in the gardening community, especially this time of year as people get ready to force bulbs for indoor blooms. Unfortunately, that enthusiasm isn’t evident among researchers. Neither the original authors nor any other researchers have continued this work; the HortTechnology paper has never been cited in any subsequent publication.
This is unfortunate – because inquiring minds want to know WHY alcohol causes narcissus stems to be shorter. Miller and Finan hypothesize that it’s simply an osmotic effect and allude to preliminary data that support this, “but additional work will be needed for confirmation.”
So I’ve looked into other scientific articles about ethanol and roots for insights into this phenomenon. There’s nothing on narcissus, but others have studied trees, forsythia, tomato and barley reactions to root-zone ethanol. In all of these cases, exposure to ethanol resulted in reduced root growth, decreased water uptake, and reduced leaf transpiration.
How does this translate to shorter stems and leaves? A reduction in water uptake and movement through the plant – that is, from roots through the stems and out of the leaves – can reduce movement of growth regulators like cytokinins from roots to stems and leaves. It can also mean that the plant contains less water and is less turgid as a result. Both growth regulators and cell turgidity are important in cell division and elongation. Reduced cell expansion will cause stems and leaves to be shorter and/or smaller as a result. This same phenomenon can be seen in plants grown under saline or droughty conditions: these plants are always smaller than their normal counterparts.
So what your grandmother used to warn you about is true – alcohol WILL stunt your growth!
Want more bird visitors? Nonnative plants may be the answer
We’ve posted before about the native vs. nonnative conundrum, especially as it relates to invasive species. So let’s complicate the issue a bit more by considering how birds are affected by our landscape choices.
About 10 years ago my UW colleague Sarah Reichard and I collaborated on a literature review on the interaction between birds and non-native plants. While we know that invasive plants can displace native plants and create less biodiverse environments, the resulting impact on species like birds is not so cut and dried. And what about noninvasive, nonnative plant species? How do they affect bird populations? Here are some of the practical bits of information that we found:
1) Nonnative shrubs and trees are often chosen for their brightly colored fruits, especially those that produce them in a different season than native plants. Winter color is highly valued by gardeners.
2) Frugivorous birds (those that eat fruit) generally benefit from the introduction of fruiting species as an additional food source, even if the species is invasive.
3) Birds tend to prefer fruits that are red and/or black, or that have red arils or pseudoarils.
4) Birds tend to prefer fruits that offer the most pulp; interestingly, highly invasive plants species tend to have larger fruit displays and therefore higher bird usage than less invasive relatives.
5) Additional food sources can allow frugivorous and omnivorous birds to expand their ranges and/or their breeding seasons.
6) Nonnative shrubs and trees with structural features such as thorns and spikes can provide protection to small birds from predators.
It’s clear that birds are highly adaptive and will quickly learn to utilize new food resources – and in doing so, may contribute to their spread through seed dispersal. It’s enough to make your head spin.
Here’s what I recommend for choosing bird-friendly trees, shrubs and vines:
1) Use native species first if they are adaptable to your site conditions. (Note: many native species, especially those of forested environments, don’t like urban conditions.)
2) Be sure to provide structural diversity in your landscapes – groundcovers, small dense shrubs, larger open shrubs and small trees, big trees, and vines – to provide shelter and nesting habitat.
3) Before choosing nonnative species, check the web for information on invasiveness. The USDA Plants Database (http://plants.usda.gov/) has information on invasive species. If it’s invasive, please don’t plant it!
4) Birds see best in the red end of the color spectrum, so select plants with fruits and flowers that will attract them.
Mysterious glowing object identified!
Ed, Wes and Paul all correctly identified Friday’s flower as a morning glory, probably an Ipomoea spp. (They also made me feel rather soiled for pedaling flower porn. Sheesh.)
What I find fascinating about these flowers is the unearthly glow at the center. They’re pollinated by bumblebees among other species, and bees see best in the blue-violet-ultraviolet range. If we were able to see this flower under UV light, you’d see those white areas become completely dark, creating a bullseye for bee approach.
Here’s why the white areas turn dark. The pigments in a white flower are flavonoids, which absorb UV radiation and reflect visible light. We don’t see into the UV range, so to us they look white (all that visible light bouncing back). But bees and some other insects do see UV light, and these flavonoid pigments create patterns to help them find nectar and pollen.
Glowing mystery
Here’s a snippet of a photo I shot this summer:
What is this mysterious glowing object? (I did not manipulate this photo in any way other than to crop it) Answer Monday!
By the way, Lynn asked if we could do a posting on how to make our landscapes more wildlife friendly. We’re doing even better than a posting – we’re doing a whole week’s worth of blogs on the topic! Thanks for the suggestion – and the rest of you feel free to suggest topics as well.
Newsflash: trees will die if their roots can’t establish
I’ve blogged before about the importance of getting tree roots in contact with the landscape soil during transplanting (you can find those posts here, here, here, here, and here). My advice to bareroot woody species upon installation is often ignored in favor of the quick-n-easy methods so often showcased on HGTV (“A complete landscape makeover in a weekend!”). And of course everything looks great…for a while. Let’s see what happens after a few years.
Below are photos of a pine tree, several of which were installed in 2007 at my children’s school (The Bush School in Seattle):
Not only is this pine tree planted too deeply (you can’t see the root flare, so it’s too deep), but the twine and burlap were not removed, leaving the roots encased in clay. Furthermore, we’re not sure how great a root system this tree has since we can’t see it. Even more horrific, the orange nylon twine is beginning to girdle the trunk. What’s been planted is a big ball o’ trouble.
I sent these photos and my concerns to the administration and advised them to have the installers (low bid, of course) redo the planting before the one year warranty expired. My advice was ignored, and here we are three years later:
This particular tree has declined to the point that the foliage is chlorotic and the uppermost needles are dead. It’s symptomatic of a root system that has failed to establish, which is what I predicted would happen. But it’s long past the warranty period, so if this tree is replaced the school will have to pay for it…again. (Though it’s hard to see in this compressed photo, the pine next to this one also has top dieback, and I’ll continue to follow its decline.)
Many professionals, including some of my fellow GPs, disagree with the bare-root approach. But based on this evidence, how could one argue that bare-rooting would not have been preferable to decline and death?
Tricky tricolor leaf
Well, this was a tricky puzzle! Here’s a more complete picture of this interesting plant:
This, believe it or not, is a weigela – specifically, a patented cultivar named Kolmagira. You can see part of a tag in the lower left part of this photo:
As the patent description reads, this shrub possesses “…yellow green and dark green variegated leaves with purple-colored margins…”
Some of you guessed that the leaves might be variegated due to fall senescence, or disease, or drought stress – all very good guesses. And now I’m going to reveal one of my biases (yes, I am opinionated! I know you’re surprised!)
I dislike these types of cultivars because they look environmentally stressed and/or diseased. I’m a plant stress physiologist by training, and that’s just the way I look at abnormal leaf coloration. And on a more aesthetic note, do our gardens really need these tarted-up plants? Let’s discuss it!
Autumn leaf? Or is it?
It’s that time of year – leaves are turning all shades of yellow, orange, and red – so I thought I’d use this leaf for today’s puzzle:
I had to photoshop this extensively so it’s a little rough looking. But it does have a toothed margin.
So – is this an example of autumnal coloration? Or something else? Extra bonus points if you can identify the genus of this plant.
Answers and another photo on Monday!
Time for another WOW (Why oh why)!
During my nursery visits this summer I came across Taxodium distichum ‘Peve Minaret’, a dwarf cultivar of bald cypress. I hate it:
Why? Because it’s a crummy specimen. If it’s not quite clear, here is a close up of the double leader:
I’ve ranted a couple of times about the production nursery practice of topping young trees to create fuller crowns (you can see those posts here and here). I’m constantly taken to task for this, with comments along these lines:
1) There’s nothing wrong with it. Customers like the look.
2) After topping the production nursery selects a new leader.
3) If the production nursery doesn’t select a new leader, then the retail nursery should.
4) If the retail nursery doesn’t, then it’s the customer’s job to do it.
5) If the customer doesn’t, then an arborist should catch it.
Somehow it’s always someone else’s responsibility to do the corrective pruning needed to prevent future problems. Yet I have not seen a cogent argument about why this practice is necessary (and “customers like the look” doesn’t count). In fact, a recent email told me I’m approaching this all wrong:
“I think it would be better for you to attack this problem by teaching the maintenance industry on how to remove a few poor branch angles, and make a profit on this, then to tell the consumer that they don’t know what looks good to them.”
Aha. So we get unsuspecting customer to buy a problem tree, then charge them again to fix it!
It’s not like I have to look very hard to find these trees in nurseries. Believe me, they’re everywhere, at least in this part of the country.
So…proponents of this practice. Convince me (1) that there is a valid, evidence-based reason for this practice, and (2) it’s okay for trees like this bald cypress to end up in retail nurseries.
Dig it up and give it another chance!
Too often I’ve come across relatively young trees, shrubs, and vines that are surviving, but not thriving. Every year they struggle gamely to put on a few new leaves, grow a few more inches, but something’s fishy and it’s not fertilizer. Today I’m going to try to convince you to give these languishing woody species a second lease on life.
Long-time readers of this blog will remember some of the root horrors I’ve (literally) uncovered in containerized and balled-and-burlapped plants. Poor root quality, improperly amended soil, roots swaddled in multiple layers of materials, and root crowns sunk far below grade are some of the most common reasons why roots fail to establish after transplanting.
Fall can be a great time to correct these problems. For deciduous species, it’s best to wait until the leaves have fallen so that water needs are reduced. You can find basic instructions on how to install and care for woody plants on my web page.
There are other reasons that plants might not establish, too. You might remember my long-suffering Clematis, two which had been planted in an area with a perched water table. The lack of oxygen both retarded root growth and created an iron toxicity problem. I dug them up and transplanted them into containers (during which I had even more fun with overmixing the soil with water and then allowing the undersides of the leaves to sunburn). They were pretty sorry looking back in July – most of the leaves fell off after being burnt – but here they are just two months later:
So while you’re out putting your landscape to bed for the winter, take a close look for stragglers. Give their roots another shot at survival – you’ll be glad you did.