The new Piedmont Habitat display garden at the North Carolina Botanical Garden has given us the opportunity to try out some new plants. The fact that this particular garden is occupying a former (paved) road corridor meant we could grow plants that need a lot of light (see previous blog post dated December 21, 2011).
One section or “bed” of this garden displays plants found growing on the mineral diabase in plant communities referred to as glades or barrens. These plant communities are dependent on natural disturbances (e.g., fire or herbivores) that minimize competition in the understory and create situations with ample light levels.
You may remember that a few years ago (2009, to be exact) the NC Wildflower of the Year was Piedmont Barbara’s-buttons (Marshallia obovata). With buttonlike clusters of white flowers topping slender stalks, that Marshallia was described, in our own words, as “simultaneously sturdy and delicate, cheerful and elegant, petite and eye catching.” Its natural habitat is dry open woodlands and sunny edges, and we do display it in the Piedmont Habitat Garden. In fact, it has just about finished up blooming.
But take a look at this other, gorgeously tall, purple-tinged Barbara’s-buttons that began blooming last week in the diabase glade section of the Piedmont Habitat. (Note that large leaves with serrated edges in the background are from a Parthenium plant—not the Marshallia.)
Our staff collected seeds for this beauty—“Oak-Barrens Barbara’s-buttons”—at a protected diabase glade site where powerline right-of-way maintenance and prescribed burning have enabled remnant populations of shade-intolerant plants to survive. The nomenclature of this Marshallia species is currently being worked out by Dr. Alan Weakley, curator of the UNC Herbarium .
This photo shows how Marshallia sp. 1 looks as it is just starting to bloom.
Don’t expect to see this plant offered in our Daily Plant Sale. It is very rare, “known from three extant populations and one extirpated population, in Granville County, NC, and Halifax Co., VA, where [it is] associated with numerous rare and disjunct taxa of prairie or barren affinities” (from Weakley, Flora of the Southern & Mid-Atlantic States, May 2011 draft). The Garden’s policy is not to offer for sale plants known to be exceedingly rare or threatened, with few exceptions:
“The overriding policy of the North Carolina Botanical Garden is that its activities will support the conservation of the plants and natural areas in North Carolina and the Southeast. Our sale and promotion of [the] horticultural use of rare plants shall be accepted when these activities benefit conservation goals [my emphasis] and will be rejected when these activities compromise conservation goals.”
Read the full text of our Policy on the Sale of Rare Plant Species here and come by to see this intriguingly rare Marshallia soon!
—Laura Cotterman
Weeds are big attention-grabbers at this time of year. Last weekend, as I weeded a particularly wild and unmanaged wildflower plot at my home, I thought about my attitude toward weeds. The modest 4-by-4-foot bed I was working in is where I have randomly, with no attention to design, planted perennials brought home from the North Carolina Botanical Garden. The verb “planted” suggests more intention than I can claim: it’s more like I hastily stick them in the ground, water once, and nearly forget about them. Furthermore, over the years, some non-native, albeit pretty, plants—for instance blackberry lily—have found their way into this square of ground. I can’t seem to refuse a pail-full of plants passed along by a friend. Fortunately, these nonnative delights have remained understated (i.e., under control). But not so the “weeds.”
On this spring Saturday I was yanking the usual—yellow clovers, sorrels, Bermuda grass—from this unruly bed. After a few minutes, one aggressive interloper started raising a sense of alarm in me. A delicate, clambering, white-flowered vetch, this annual, it turns out, is not native; I did NOT put it there!
Vicia hirsuta, tiny vetch, comes from Europe and Asia, though by now it is found throughout eastern, southern, and western North America; only the mid-sections of Canada and the U.S. are unaffected. Searching some sources on the Web, I found that V. hirsuta is viewed as a weed of agricultural crops in a lot of places, including Eastern Europe and Russia. With its hair-thin but tough tendrils it will hang on stubbornly to other plants, it continues growing after you pull it, unless you grasp it at the very bottom and extract the roots (and believe me, it is hard to find the “bottom” of this viney-thing). The many short, two-seeded pods are quick to ripen in the spring, too. It wouldn’t surprise me to learn that the seeds persist in soil for many years.
(photo by Jean Pawek)
What is “a weed”? A plant we don’t want that more or less aggressively invades a space where we’d like to be growing something else? Well, yes! Often it is not native to our geographic region—though this is not always true (think poison ivy). It seems that we never would have come up with the concept if we hadn’t developed the impulse to cultivate the earth with plants that WE wanted. Couple that with the fact that we move plants, soil, and our bodies, to which seeds attach themselves, around the globe—it’s no wonder there are a lot of “weeds.”
Yesterday I looked through a shelf of books on weeds in our library at the Botanical Garden (did you know that we have an excellent library, and anyone is welcome to come by to use this treasure trove of references? note: books must remain on the premises). Take a look at these marvelous titles I found:
- A Manual of Weeds with Descriptions of All of the Most Pernicious and Troublesome Plants in the United States and Canada (by Ada E. Georgia, 1927)
- Wildly Successful Plants—A Handbook of North American Weeds (by Lawrence J. Crockett, 1977).
“Pernicious” and “Troublesome” are terms freighted with bias—understandably so, I might add. But the second title captures the essence of “weeds” for me. Weeds are plants that have been wildly successful in occupying multiple geographies and reproducing themselves there. There are many, many strategies for accomplishing this, including tendrils and a vining habit that make the plant hard to remove, seeds that can germinate for several to many years after dropping to the ground, rhizomes that break off in the soil and re-sprout after the plant has been pulled up (a good example in my garden is sheep-sorrel, Rumex acetosella), and one of the most clever of all—getting an animal (like us) to carry you to a new place where there are no predators (herbivorous grazers and insects) that like to eat you or diseases that will kill you. For this last, think of Japanese stiltgrass, Microstegium vimineum; even goats won’t eat it!
I am not a very diligent gardener. The long hot summers here leave me defeated by July, so I often don’t attack my garden weeds as heroically as I might. I give up and by September, they’ve dropped a million and one seeds—a situation that, I am all too aware, makes the next year even more challenging.
The tiny vetch in my garden caught my eye last year and I did pull at a few tangled strands. It gets going fairly early in the spring and displays miniscule white flowers soon after. But the thin stems and slender pinnate leaves were sort of appealing, in small numbers, so I didn’t take it seriously. What a mistake! Short, fuzzy seed pods appeared very quickly, and before I knew it, pulling was pointless because each yank released a crop of seeds from the now brown pods.
I try not to judge any plant too harshly, calling it names and cursing its very existence. After all, it is only doing what comes naturally! Nevertheless, weeds do need to be dealt with in a timely manner if we are going to be gardeners. I’m in favor of the slow and steady method of “editing” out (a term used by “queen weeder” at NCBG, Sally Heiney) the plants we simply don’t want taking up valuable space in our cultivated ground and who generally won’t serve as food and shelter for our native species of insects—who, in turn, serve as food for the native birds we take pleasure in seeing and hearing when we sit down on the porch to rest and drink a glass of cool water after a morning of weeding.
—Laura Cotterman
Sometimes I wonder if it is really possible NOT to love plants.
Now that we are approaching the “great green interlude”—when the fantastic flush of spring flowering subsides and it is just about too hot for moving things around in the garden—we can kick back, under the leafy canopy, and reflect on how fortunate we are for these organisms who green our world and make life possible: literally.
Douglas Tallamy writes: “Plants are not optional on this planet … . Nearly every creature … owes its existence to plants, the only organism capable of capturing the sun’s energy and, through photosynthesis, turning that energy into food for the rest of us.” Think about it: not only would agricultural crops disappear, but so would all other forms of life—insects, birds, mammals, reptiles, amphibians—if plants were to go missing. Really, everything.
And when you take time to notice the myriad forms they come in, isn’t it also true that plants are marvelous? From the surely infinite number of deciduous leaf shapes, not to mention the cleverness of deciduousness itself (surfaces for capturing sunlight during the brightly lit time of year, then release of those light-gatherers during dimmer times) and yet another option—coniferous leaves, to seductive contrivances for pulling-in pollinators (nectar, flower color/pattern, mimicry), and the many means plants use to “get around” despite a lack of true mobility (rhizomes, runners, bulblets, spring-loaded seed capsules, high-energy fat droplets on seeds) … yes, there is no end to the intricacy and diversity of the plant world.
I’ve been wondering: why the deep maroon color of these Eastern sweetshrub/Carolina allspice flowers (Calycanthus floridus)? And why that peculiar scent combining hints of pineapple, strawberry, banana, and maybe a touch of allspice? I don’t know, yet, which pollinator is attracted to these colors and smells.
But how different from that shrub’s dark, open-air flowers is this pale, tucked-under flower of the mayapple (Podophyllum peltatum)? Whoever visits this bloom for nectar/pollen must be low to the ground.
I encourage you to be curious about the botanical universe around you, and to discover that a public garden is a great place to become acquainted with these organisms that sustain us. May 11 is National Public Gardens Day, and the North Carolina Botanical Garden will join with 21 other public gardens throughout North Carolina, and more than 500 public gardens across the nation, to encourage communities to discover the natural beauty of their local green spaces and learn about the important role public gardens play in promoting conservation, education, and biological diversity. Join us for the events posted here: http://ncbg.unc.edu/uploads/files/NPGD2012_2.pdf
—Laura Cotterman
For about a week now, we’ve been in a “Wisteria Daze.” What I mean is, vines of the Asian species of Wisteria are blooming everywhere. Here in Chapel Hill, they are particularly in-your-face along sections of Fordham Boulevard, not too far from the North Carolina Botanical Garden.
(Chinese wisteria [Wisteria sinensis] by Randy Westbrooks, U.S. Geological Survey, Bugwood.org)
When I pass a grove where whole tops of trees are being pulled down by these extremely aggressive woody vines, I reflect on how Wisteria represents the South—and warm spring days in the South—to a lot of people. Then I think of our lovely, later-blooming native Wisteria species—Wisteria frutescens—and wonder why anyone would have wanted to bring the Chinese (Wisteria sinensis) or the Japanese (Wisteria floribunda) species into their gardens in the first place. Apparently, this happened in the early 1800s.
From www.invasives.org (Center for Invasive Species and Ecosystems Health):
Chinese wisteria is a deciduous woody vine capable of growing to a height of 40 ft. Stems can be up to 10 in. in diameter with smooth, gray-brown bark… . Lavender, purple or white flowers are fragrant, very showy and abundant and occur in long, dangling clusters in the spring… . . Invasions often occur around previous plantings. Chinese wisteria can displace native vegetation and kill trees and shrubs by girdling them. The vine has the ability to change the structure of a forest by killing trees and altering the light availability to the forest floor… .
Now I’m not saying Chinese wisteria isn’t pretty. BUT, consider our native species:
This photo, taken here at the N.C. Botanical Garden a few years ago, shows a favorite cultivar of the native, American wisteria: Wisteria frutescens ‘Amethyst Falls’ (with a bit of coral honeysuckle in the upper right corner). It blooms a little later than the Asian species—this photo taken May 9, though this year I’d wager it will bloom in April. AND, it blooms after the shiny, dark-green foliage has emerged, providing a sweet backdrop to the dense clusters of blue-purple flowers. The clusters are generally smaller and more compact than those of the Asian wisterias, and as a whole, the vine is well-behaved: regular pruning will keep it where you want it. Another wonderful feature: it starts blooming at a very young age, so you don’t have to wait to get those gorgeous cascades of fragrant flowers.
Best of all? You can buy it at the North Carolina Botanical Garden’s daily plant sale—at least right now we have a few plants (no guarantees on supply). And if you purchase here, you’ll support the work we do to promote the use of native plants in the landscape: plants that support the pollinators and wildlife you love.
—Laura Cotterman
This is one spring that seems to be rushing forward. Plants are opening up blossoms in such quick succession that my head is spinning. Trout lilies lasted a long time, but I think I missed the Hepatica—and anyway, now we are on to Phlox. Last week, I looked up one day and the Redbuds were blooming. Then it was the Dogwood blossoms. Now native azaleas, such as Pinxter Flower (Rhododendron periclymenoides, above) and Florida Azalea (R. austrinum) are about to pop. Then … well, really, I’ve lost any sense of time here!
This week it is a flush of leaf emergence that has my attention. Hillsides are blushing green, and I am enamored with the baby leaves—miniatures of their summer selves. Take a look at these:
Grape (Vitis sp.)
Oak (possibly Quercus marilandica, Post Oak)
Sweetgum (Liquidambar styraciflua)
I hope you are out and about, taking this all in!
—Laura Cotterman
