In my opinion, no coastal Pacific NW garden is complete without moss softening the edges of a rock garden or nestling between paving stones. Now that the rains have returned, mosses are lush green sponges, absorbing sound as well as water. They are the finishing touches to our native landscapes.
Bloedel Reserve moss garden
A few months ago, however, mosses looked quite different. With our particularly hot and droughty summer, mosses were brown, dry and brittle just like our lawns. But unlike those dead blades of grass, the mosses were only in a state of environmental dormancy. All it took to revive them was water.
Here’s a patch of moss in our home landscape during a hot dry spell. It’s dry and brown:
Dormant moss
Here’s the same patch of moss 20 minutes after I watered it:
It’s a garden miracle!
How can mosses recover so quickly? Well, mosses are one of the most primitive groups of land plants still in existence. They lack a true vascular system, so their “roots” are only anchoring structures – they don’t absorb water. Instead, water and nutrients are taken up over the leaf surface. As soon as water hits the leaves, it’s absorbed and literally throws the switch to turn everything back on. Leaves expand, chloroplasts start to absorb sunlight, and the photosynthetic machine is humming along.
In fact, my undergraduate major advisor was a bryologist (one who studies mosses). Jack Lyford’s lab was stacked ceiling-high with shoe boxes. Each box contained a different species of moss – completely dried out of course. All he had to do was take out a piece and place it in a dish of water. Within minutes it was fully functional and ready for study.
So make room for some moss in your garden. It’s a tough and fascinating little survivor.
The last two winters have been pretty brutal on my citrus trees. Their winter home is the enclosed, but unheated, south facing entrance foyer. Usually, this is a perfect spot. Sunny, and with temperatures usually in 45-60 degree range. But when the polar vortex brought record cold to the Mid Atlantic region back in February, they were hit hard, and I had my doubts that this 13 year old specimen would survive.
Happy Citrus
But it bounced back pretty well, after a season in the sun, so I figured it should be rewarded … I’d give it a new home, replacing its split container … and document the process here.
Lots of discussion recently over on the Facebook side regarding the recent publication in Ecological Letters by Karin Burghardt and Douglas Tallamy, “Not all non-natives are equally unequal: reductions in herbivore β-diversity depend on phylogenetic similarity to native plant community.” http://onlinelibrary.wiley.com/doi/10.1111/ele.12492/full
While there are certainly some things to nitpick in the paper (see Linda’s comments on the Facebook discussion), I think this paper may go a long ways re-shape, and possibly even begin to end, the debate over native versus exotic.
How was the study conducted. In 2006 Tallamy’s group established a series of test landscape plantings. Each planting fell into one of four groups: non-native congeners (species that are not native but have native relatives in the same genus); non-native non-congeners (plants from non-native genera), native congeners and native non-congeners. In 2008, when the trees were about 6’ (1.8 m) tall, they conducted a census to identify and quantify the adult and immature insect herbivores they collected. They analyzed the data to determine the amount of insect herbivore diversity within each planting type. Specifically they looked at what ecologists refer to as beta-diversity, the amount of species diversity among sites. If you’re interested and want to learn more check out https://methodsblog.wordpress.com/2015/05/27/beta_diversity/
So, what did they find? Like every good study on host-insect interactions; the answer is, “It depends.” (BTW, if you’re following along at home the key figure in the paper is Fig. 3). When Burghardt and Tallamy looked at the differences in diversity between adult herbivores on native and non-native congeners, they found no difference. When they looked at differences in diversity between immature herbivores on native and non-native congeners, they found no difference. When they looked at differences in diversity between adult herbivores on native and non-native non-congeners, they found no difference. When they looked at immature herbivores on native and non-native non-congeners, they found a small but statistically significant difference, with higher total diversity for native non-congener.
As an aside, it is also instructive to look the version of Figure 3 presented in the article’s supplemental materials, which has been re-scaled to include zero. Including zero on the scale helps to give a better perspective on the actual variation among means. It’s a little like the “Truth in lending statement” that comes at the end of your credit card bill.
So, a possible alternative title for the paper could be, “Do native or non-native plants increase herbivore diversity? Most of the time it doesn’t matter.” That said, I think this paper makes a number of contributions and will start to shift native versus non-native debate, and perhaps even signal the beginning of the end. First of all it demonstrates that that non-native species of native genera contribute equally to herbivore diversity. However, I think some of the most insightful information in the paper is buried between the lines and in the supplemental information attached to the online version of the paper. The authors briefly mention that they also looked at guilds (i.e., chewing insects, sap feeding insect, xylem feeders, etc.). Once again the answer of whether natives contribute more to species diversity is, “It depends.” For xylem feeders, for example, diversity was the same for congeners and non-congeners.
To me, this is the level of resolution we need to work to gain a true handle on the situation. I’m not an entomologist and I’ve never played one on TV but I’ve been around these questions long enough to know that different types of insects are attracted to or repelled by different plants by different mechanisms. In one case it’s an attraction pheromone, in another it’s a defense chemical, sometimes it’s leaf toughness or a tree is able to produce enough resin to drown boring insects. An old axiom states that ecosystems are not more complicate than we think; ecosystems are more complicated than we can think. As this paper demonstrates, to think that all the complex interactions between plants and insects can be boiled down to something as simple as native or exotic is hopelessly naïve.
I’ve been grafting cactus this summer, and made this:
It is a seedling of the gorgeous hardy cactus Echinocereus reichenbachii, grafted onto Pereskiopsis spathulata, an odd, leafy cactus I wrote about earlier.
Why do this? Other than the fact that it is darn cool? Well, because that vigorous, fast growing rootstock pumps a lot of energy into the cactus grafted on top, making the grafted cactus grow a LOT faster than left on its own roots.
This is a (terrible, blurry) picture what the graft looked like when I first made it back in July. Just three months later it has grown to enormously, while the seedlings I left on their own roots look pretty much the same. I’ll let it grow on the graft for a while, then probably next year some time, cut it off, and move it into the garden, getting me to a reasonably sized plant in a reasonable amount of time.
So… if you want to speed up the growth of a pokey cactus, try grafting it. The process is crazy easy, lots of fun, and very thoroughly explained here.
It’s October. Fall is such an underrated time in the garden, and much pink can be found. In fact, flashes of pink are everywhere!! Got my ma’ams grammed last week; thanks for the reminder, NFL.
Muhlenbergia ‘Pink Flamingo’. Aye yi yi. Alleged hybrid between M. capillaris and M. lindheimeri. Five feet tall and as wide, huge plumes of pink. Looks like nothing important the rest of the year, then, blammo!!! Sorry, folks north of Zone 6. Actually, it only works here (Z. 6a) because of outstanding drainage; it’s planted in a pile of gravel. Mine has lived through two winters with -20 F days. Place where the sun will rise or set behind it for maximum effect. Bunny the Whippet not included.
Salvia involucrata – Rosebud Salvia
Big ol’ gal that will not favor you with blossoms until September. Absolutely not hardy here, or anywhere north of Zone 8. Take cuttings, ’cause baby she’s worth it. The furry, hot pink flowers will thrill any hummingbirds left zipping around (I read ours the riot act this weekend, they have GOT to hit the road soon). Note there is some hullabaloo as to S. puberula vs. S. involucrata vs. some hybrid amongst the two. Will report back.
Chrysanthemum x whatever ‘Venus’ .
Am so tired of the taxonomic uncertainty. Chrysanthemum…Dendranthemum… Whatever you call her, ‘Venus’ is a wonderful “real” garden mum (not those heinous meatball things) that brings the pink blooms in September, then fades to palest of pink, but not before every bee in the neighborhood visits. Fairly compact (2-3’) and pretty darn hardy (Zone 5). Tuck Venus amongst things you know will be done before fall – bee balm, phlox, etc. to keep the show going!
So there you have it, some pink for our October gardens. In loving memory of my sister Carlene.
A walk through the woods can be one of the most peaceful and calming experiences — a place where you can find quiet for reflection and marvel at the beauty of nature. Little do most people know that some plants, especially one specific tree, wage chemical warfare against other plants to keep away potential neighbors that would compete for nutrients and sunlight. In the Appalachian Mountains, the tree most skilled at chemical warfare is the black walnut.
The black walnut tree (Juglans nigra) is a useful, yet often misunderstood tree. Prized for its excellent wood qualities for lumber and furniture, the nuts it produces are either loved or reviled by those who try them.
The flavor of black walnuts is hard to describe. I would say that they have an almost astringent flavor, mainly due to the high level of tannins in them. They aren’t my favorite, but I don’t mind them either. I’ve learned to accept them, unlike during my childhood when you knew which church lady’s cake to avoid at the potluck because you knew that she put black walnuts in everything she baked.
My appreciation for black walnuts grew the year that I was the official nut judge (no joke) for the Black Walnut Festival in Spencer, WV. It was quite an experience — examining and weighing all the entries with a team of high school FFA students who cracked more than a few inappropriate jokes about the situation.
You could tell when someone was picking or cracking black walnuts, thanks to the tannin stains on their hands that just wouldn’t wash off. Black walnuts are a tough nut to crack (literally), so I also remember my grandmother cracking them “the easy way.” She would just pile them up in the driveway and run over them a time or two with her behemoth of an Oldsmobile (you know, the one that had full seats front and back and could hold half the neighborhood).
Black walnut trees have the interesting ability to excrete a chemical called juglone, which makes it nearly impossible for a number of plants to grow anywhere in its root zone. Juglone works by damaging the tiny root hairs on roots that are responsible for taking up a great majority of the water and nutrients the plants use. Research shows that it also interferes with the interaction of the roots with mycorrhizal fungi that aid the plant in taking up nutrients.
This process is not just specific to black walnuts. There are several other plants that do this. The phenomenon, called allelopathy, occurs when an organism excretes something that inhibits the growth of other things around it. You could equate it to the Penicillium fungus excreting a chemical that kills bacteria around it. We harness that chemical to use as penicillin.
Some plants are especially sensitive to the chemical. Many vegetable plants, especially tomatoes, are sensitive. Some plants, mainly those that would grow wild in the woods, are not susceptible. Many grasses also have a hard time growing beneath black walnut trees (tall fescue and Kentucky bluegrass being the exception, except during periods of drought).
All parts of the tree produce the juglone chemical, so the effects could spread beyond the perimeter of the tree from fallen leaves and branches. I would also suggest that you make sure any fresh woodchip mulch that you use (specifically that from local tree cutters) is free of black walnut. The juglone may break down after composting the wood chips for six months to a year, but I would still be cautious about its use. The wood will release the chemical, killing susceptible plants for a few years in the area where it is applied. Studies suggest that juglone will break down during the composting process, but I would check to make sure by starting a few tomato seeds on the batch of compost to see what happens.
—Garden Professor John Porter is a county extension agent for West Virginia University and writes the weekly Sunday garden column for the Charleston Gazette-Mail Newspaper. This article was originally published October 2, 2015.
As promised in my Sept. 9 post of “The Science Behind Fall Color”, I would address trees and shrubs with outstanding fall color. It was hard limiting it to only ten trees and ten shrubs, since I found 5 common shrub species of maples alone, so I cheated a bit and grouped the maples, oaks, etc. into one group so that my list was not entirely all maples.
‘Robin Hill’ apple serviceberry (Amelanchier x grandiflora ‘Robin Hill’)
I have seen the below plants with reliable fall color in northern, southern and eastern landscapes. These plants “light” up the landscape in autumn. For outstanding, long lasting autumn color, plant the below trees and shrubs with herbaceous plants which bloom in fall such as asters, mums, sedums, monkshood, toad lilies, and Japanese anemones. Do not forget ornamental grasses with their showy seed heads extending the season of color and texture.
Sweet birch, cherry birch (Betula lenta)
We used to recommend ash for fall color, but not any more due to emerald ash borer. Japanese barberry and burningbush are tops for fall color, but both species are highly invasive and not recommended. There are more plants with great fall color than the ones below. I would love to hear your favorites!
Top 10 Trees for Fall Color
1) Black gum, sour gum, tupelo (Nyssa sylvatica), orange-red, scarlet to purple, outstanding
Black gum, sour gum, tupelo (Nyssa sylvatica)
2) Maples, especially:
Sugar maple (Acer saccharum), bright yellow to orange-red
Red maple (A. rubrum), yellow, orange-red to bright red
Freeman maple (A. × freemanii), yellow, orange-red, red to reddish-purple
Paperbark maple (A. griseum), dark red to bronze
Japanese maple (A. palmatum), orange, red to purplish-red
Korean maple (A. pseudosieboldianum), deep orange to reddish-purple
Three-flower maple (A. triflorum), orange
Full moon maple (A. japonicum), yellow-orange to scarlet-red
Moosewood, striped-bark maple (A. pensylvanicum), bright yellow
3) Ginkgo (Ginkgo biloba), bright golden-yellow
4) Thornless honeylocust (Gleditsia triacanthos f. inermis), bright golden-yellow
Inspired by Linda’s post about thigmomorphogenesis, I decided today I would add the word gravitropism to your vocabulary. It simply means growth in response to gravity. Shoots of plants grow up, because they are negatively gravitropic, they grow against the pull of gravity, while roots are positively gravitropic and grow down towards the pull of gravity.
And why is that so important? Well… this is what happens when gravitropism is missing.
To the left is normal old corn. The plant to the right was not sat on by a raccoon or anything, it simply has a mutation in a gene called lazy plant1. I’m not kidding. That’s the official, scientific name for this gene. Geneticists have fun with their names, though fruit fly geneticists are for sure the kings of silly gene names. This gene got that name because, as you can see, without a functioning copy of that gene, the corn plant no longer can detect the pull of gravity and so flops down in a “lazy” manner.
This corn is just odd, of course, with no real value (though it was fun to grow) but similar mutations are what give us some of the “weeping” or trailing forms of popular ornamental trees and shrubs.
I just finished reviewing 4 manuscripts for three different journals and boy is my brain fried. My private reactions ranged from “I can’t wait until this one is published!” to “If I were to use sheet mulch this manuscript would be my first choice.” Anyway, it was the latter manuscript that got me to thinking about what can go wrong with experimental design, which brings up today’s word: thigmomorphogenesis.
This is a great word for those who enjoy figuring out word meanings by deciphering the (usually) Greek or Latin roots. (This exercise also helps you figure out how to pronounce it.) We have “thigmo-” which means touch, “-morpho-” which means appearance, and “-genesis” which means beginning. String them all together and you get the phenomenon seen when plants respond to mechanical stimulation by changing their growth pattern and hence the way they look.
Wind direction from the right creates an asymmetric hedge.
You can easily see examples of thigmomorphogenesis in everyday life. Look at a line of hedge plants where the plants on the end are more susceptible to wind movement and brushing by people, animals or vehicles. They are always shorter, aren’t they? Plants subjected to chronic thigmomorphogenic forces are generally shorter than their neighbors and thicker in girth. (For a longer discussion about how thigmorphogenesis works, you can read my online column.)
How does all of this relate to experimental design? Well, think about what happens if you are testing a product that requires applying it to the leaves of plants once a week. Your treatment plants are touched every week. How can you know that any changes in your experimental plants aren’t due to being touched? The way you eliminate this source of variability is by treating all of the plants the same way. When you are applying the product to the treatment leaves, you apply water (or whatever the solvent is for the product in question) to the control leaves. That way thigmomorphogenesis remains just an interesting tongue-twister and not a fatal design flaw in an experiment.
One of the questions that came up regularly when I was working the hotline at the local county Extension office, is a recommendation for an evergreen ground cover for shady spots. I had the same issue when I created my own shade garden … something that would have year round interest, but complement my desire to emphasize native species, although that was only one consideration.
The solution was literally right next to me, as a walk in my woods revealed with the lovely plant Partridge Berry, or Mitchella repens.
Not only is Partridge Berry (Mitchella repens ) beautiful, evergreen, shade-loving, and native to Eastern North America, but there’s also a fascinating aspect about its flowers and fruit, from a botanical, and evolutionary point of view.
According to the U.S. Forest Service Celebrating Wildflowers website, the “… genus name Mitchella was given to this plant by Linnaeus for his friend John Mitchell, a physician who developed a method of treating yellow fever. The species name repens refers to its trailing or creeping habit.”
Here’s the part I found fascinating: The plant is dimorphous, meaning “occurring in two forms”:
In late spring, two beautiful white flowers (with one calyx) each open their four petals to entice insects to collect their nectar. Each blossom has one pistil and four stamens. The pistil in one is short and the stamens are long. In the other it is just the opposite. … Because of this no flower can fertilize itself–all flowers must be cross-pollinated by insects, and both flowers must be pollinated to get a single healthy berry. A berry will stay on the vine until after the blooms appear in the spring unless a hungry bird finds it nestled among the fallen winter leaves.
How cool is that? The twin flowers produce, together, only one berry.
Here’s a closeup, where you can see residual evidence of the fusion. The berry is edible, and persists through the winter, assuming it is not consumed by “ruffed grouse, northern bobwhite, sharp-tailed grouse, and prairie chicken.
The fruit is also “frequently eaten by raccoons and red fox” and it has been reported that “partridgeberry made up 2.9 to 3.4 percent (dry weight) of the summer and fall diets of white-tailed deer.”
Here’s a picture of the two flowers in bloom.
It’s easiest to spot the plant in its natural setting while hiking in late Fall, or early Winter before snowfall, or early Spring after snowmelt.
Back to the Forest Service article:
Some gardeners consider Partridge Berry a must for winter gardens. During the cold days of late winter Partridge Berry is a treat to the eyes with its deep, dark-green leaves and occasional scarlet berries. In a garden setting this evergreen prefers shade, accepting the morning sun. Partridge Berry is extremely difficult to propagate from seed.
The best way to introduce this native into your garden is through 1 year old cuttings or by division. In the garden situation they will form a thick, substantial ground cover. Once established they are relatively trouble free with the only required maintenance of keeping garden debris from covering the mats.
As always, do not wild collect plants from public lands and only from private lands when the landowner grants permission. Partridge Berry is a commonly available plant from native plant nurseries especially those who specialize in woodland plants.
I love the symmetrical variegation in the evergreen leaves, a bright, light yellow line bisecting each leaf, and the delicate, less visible veins.
It’s a great alternative to Vinca, an introduced species from Europe that appears on invasive species lists in our area.
A Google search will reveal many potential on-line sources for buying Partridge Berry plants, or check with a local nursery, or independent gardening center in the native plant section.
This is a (terrible, blurry) picture what the graft looked like when I first made it back in July. Just three months later it has grown to enormously, while the seedlings I left on their own roots look pretty much the same. I’ll let it grow on the graft for a while, then probably next year some time, cut it off, and move it into the garden, getting me to a reasonably sized plant in a reasonable amount of time.
