On my very short commute home, we’ve designed beds along the way that help relieve the stresses of the day. One of my favorite beds in summer is this combination of Allium ‘Millenium’, Sinningia tubiflora (white), Verbena bonariensis, and Pervoskia atriplicifolia. Both the sinningia and the verbena can be a bit aggressive in some areas of the garden, but not here, where they’ve all reached a happy equilibrium. Not only are they visually attractive, but this bed is awash with pollinators, despite none of these plants being southeast US natives.
No garden is complete without at least one rudbeckia. Looking good in the garden now is the lovely Rudbeckia umbrosa. Formerly recognized as a a subspecies of the more commonly grown Rudbeckia fulgida, this is a very different plant that’s taller, and with very hairy foliage. For us, this moist woodland native tops out between 30″ and 36″, with a much more open habit. Although it’s little known in gardens, it’s actually native from the Carolinas west to Missouri. Zone 5a to 8b.
The lovely Mexican woody lily, Dasylirion berlandieri, is just finishing a bout of flowering. The flowers are magnets for both native bees as well as honeybees. Unlike their cousin, Agave, Dasylirion don’t die after flowering.
Looking lovely in the garden this week is the amazing native small tree, Aesculus parviflora var. serotina ‘Rogers’. Despite this amazing plant being native only in Alabama, it thrives in gardens well north of Chicago. This named selection was discovered in the early 1960s in the yard of University of Illinois professor Donald Rogers, and named because of its more floriferous nature, as well as its more pendulous flower spikes.
The latest member of the clumping monardas of the Electric Neon series is ‘Electric Neon Purple’. Here it is in our garden this summer, looking absolutely fabulous. Look for this in our upcoming Fall catalog.
by Patrick McMillan
The past couple of weeks the small, freakish flowers of one of the strangest of plants have begun to open in our gardens – pipevines. It’s difficult to believe that nature could summon up anything as strange as the flowers of pipevines. If you remember the “regular” aka actinomorphic and the “irregular” zygomorphic flowers from high school biology then you would have to consider the strange, inflated flowers of pipevines highly irregular.
These plants are related to wild gingers/heartleafs (Asarum) and are members of the basal angiosperms, which are plants with lineages that predate monocots and true dicots. Many of the early angiosperms have flowers that are pollinated by flies or beetles that they lure to the flowers with the pleasant smell of rotting meat or dung. Pipevine is no exception. They trick flies into entering the strangely shaped flowers which often have a funnel-like flare with a narrow opening and trap the fly in a chamber with the pollen and nectar to accomplish pollination.
The general shape of the pipevine flower also approximates the anatomy of a uterus and birth canal. As was all the craze in the early years of medicine, the resemblance to the uterus must mean it is good for treating issues with difficult pregnancies and childbirth. This archaic mode of determining herbal remedies is referred to as the doctrine of signatures – basically if a plant part looked like a part of the human anatomy it would be used to treat ailments associated with that organ. This avenue of medical care led us to the highly unsuccessful use of liverleaf (Hepatica) to treat ailments thought to be caused by the liver, like cowardice and freckles. Medical science has since progressed, maybe?
The pipevines include herbaceous upright perennials, short rambling vines, and enormous lianas (woody vines). The toxic chemical aristolochic acid is contained in all parts of the plant and though it is known to cause kidney failure (which probably didn’t decrease the problems with difficult childbirth) this chemical has also been shown to have antitumor properties. Don’t go munching on the leaves! Pipevine Swallowtails depend exclusively on pipevines for their larval food source and all the species we grow are host to large numbers of caterpillars in the summer.
The Pipevine Swallowtail accumulates aristolochic acid which deters predators like birds from wanting to consume them (they don’t want kidney failure either). This may explain why Spicebush Swallowtails and Red-spotted Purples look so similar to the Pipevine Swallowtail, they’re taking advantage of blending into the poisonous crowd.
These beautiful butterflies always seem to find your pipevines, no matter how secluded you think they are. Don’t worry, we can’t have enough swallowtails and the vines regrow without issue. These are great plants to include in your garden to support our butterflies. The caterpillars have another interesting behavior, when disturbed they have bright orange “horns” that are technically referred to as osmeteria that it pushes out of the front of its body and emit a very foul odor!
Three native pipevines are found in the Carolinas. Common Pipevine (Isotrema macrophyllum) can become a huge liana, reaching the canopies of old-growth trees and spreads through runners and can be difficult to keep contained. It grows best in cool climates and tends to suffer or not grow in warmer parts of the Southeastern US.
Woolly Pipevine (Isotrema tomentosa) grows very well in hot, humid climates and is known from only a few native populations in the Carolina coastal plain. Like its mountain cousin it is very difficult to restrain and may quickly outgrow the space you envision for it.
The only other pipevine is very dissimilar to the others, Virginia Snakeroot (Endodeca serpentaria), which is an upright herbaceous perennial that rarely gets a foot tall. If you’re wondering why these former Aristolochia are now in the genera of Isotrema and Endodeca, well, it appears to all be about genetics. They are closely related but currently in different genera.
One of the easiest to grow and showiest, best-behaved species in our garden hails from Brazil, Argentina and Bolivia, Fringed Pipevine or Fringed Dutchman’s-pipe (Aristolochia fimbriata). The plants form scrambling vines that act more like a groundcover than a vine and have beautifully silver-veined small leaves. The flowers are intricately patterned with lines and fringed with long “tentacles” to create one of the most bizarre flowers you’ll ever include in the landscape. Though you wouldn’t pick a plant from Brazil to be rock-hardy here in Raleigh, this one has been fully hardy (zones 7a-9a). For those of you looking to add some swallowtails but unwilling to devote the space to a monstrous mass of vines this one is for you. Fringed Pipevine is also incredibly drought-tolerant and perfect for part-sun to dappled dry shade.
The lovely Aesculus pavia, native from Illinois south to Texas, and east to Florida, has been absolutely glorious over the last few weeks. This easy-to-grow small tree typically tops out between 15-20′ tall.
I’d grown quite a few eryngiums…49 different ones, in fact, before Patrick shared Eryngium ravenelii with us in 2015. Who knew we were missing one of the best eryngiums in the entire genus! Today, Eryngium ravenelii holds several places of honor in our garden, where we can watch the myriad of pollinators who regularly stop by for a nectar snack during flowering season (mid-August to late September).
Eryngium ravenelii was named for American botanist, Henry William Ravenel (1814-1887). In the wild, Eryngium ravenelii grows in standing water in flooded ditches, alongside sarracenias (see bottom photo). We’ve now seen them in the wild in both North Florida and South Carolina, where they grow in calcareous-formed soils. In the garden, they thrive in an array of slightly acidic soils as long as the soil is reasonably moist.
I’ve been surprised to see the black swallowtails regularly enjoying the nectar of the summer-flowering daphnes…in this case, Daphne x napolitana ‘Bramdream’. Our plants are thriving, growing in our full sun rock garden.
As gardeners around the country are encouraged to plant more asclepias to encourage monarch butterflies, many folks are finding out that not all species of asclepias make good garden plants. As a genus, asclepias consists of running and clump forming species. There are number of horribly weedy garden plants like Asclepias speciosa, Asclepias syriaca, and Asclepias fasicularis. These plants are fine in a prairie garden, but are disastrous in more controlled home gardens.
One of our favorite clumping species is the easy-to-grow, Arizona-native Asclepias angustifolia ‘Sonoita’. This superb species was shared by plantsman Patrick McMillan. It has proven to be an amazing garden specimen, thriving for years, despite our heat and humidity. Did I mention it flowers from spring through summer?
Gardeners interesting in attracting pollinators to the garden have no doubt experimented with one of the 20 native species of Pycnanthemum (mountain mint). While they are all lovely, most are too vigorously spreading to fit in a typical home garden. Enter Pycnanthemum flexuosum…the curvy mountain mint, is native from Virginia to Alabama, where it is found on moist to damp sites. This tightly clumping species is absolutely perfect for the garden, flowering now in July. This is our collection from Beaufort County, NC. We’ll be propagating this selection for a future PDN catalog. Hardiness is Zone 5-9a.
If you get your gardening information on-line, where everything written is a fact, you’ll know for sure that acacias aren’t growable in Zone 7b, Raleigh, NC. If that includes you, don’t look at the photo below of Acacia greggii ‘Mule Mountain’ in flower at JLBG. Acacia greggii is a native from Texas west to California. Our seven year-old specimen is from Patrick McMillan’s collection in Cochise County, Arizona.
To be nomenclaturally correct, most of the US Acacias have now been moved into the genus Senegalia, so even though the American species aren’t from anywhere near Senegal, this is now known as Senegalia greggii.
Of course, it you also read the hogwash on-line about native pollinators needed and preferring plants they evolved with, then you’ll also have to ignore the masses of native bees that cause the entire plant to buzz while they’re feeding. It’s good we don’t let our plants and insects read books or the Internet.
We caught the Nessus Sphinx moth feasting on a patch of phlox this spring. Remember that garden diversity brings more fascinating pollinators into the garden.
What a lovely color echo we caught this week at JLBG when the tiger swallowtails were visiting Mertensia virginiana (Virginia Bluebells). Remember that botanical diversity results in more pollinators in the garden.
Here is the wonderful Fatsia japonica ‘Variegata’ in our garden on Oct 25. This fabulous shrub is a member of the aralia family, and a first cousin of the off-despised running ivies. Not only do we love Fatsia for its amazing bold texture and evergreen foliage, but we love it because it flowers in fall. The second photo was taken a mere four weeks later, when it had exploded in full bloom.
Fatsia japonica is a superb pollinator plant at a time when so little is in full bloom. Our winter low temperatures so far have been 27 degrees F, which hasn’t affected the flowers. Winter hardiness is Zone 7b and warmer.
I was fascinated to find these monarch butterfly chrysalis’s hanging out on an agave in the crevice garden recently. Our entomologist, Bill Reynolds, tells me that when the caterpillars are finished feeding, they will often migrate from a nearby asclepias to all kinds of odd plants to hangout until it’s time to come out of their closet. It’s hard to imagine a full-size monarch butterfly inside these little structures, but perhaps they are like Dr. Who’s Tardis.
Our favorite fall-flowering legume is looking fabulous now. While most daleas (baptisia cousins) flower in spring and summer, only one that we’ve grown waits until fall to produce its amazing floral show. Dalea bicolor var. argyraea is an easy-to-grow species, found in the dry alkaline sandy soils of Texas and New Mexico. Here at JLBG, it has thrived everywhere it’s been planted…all dry, un-irrigated beds. Native pollinators love it also.
Late summer/early fall is show season for Eryngium aquaticum var. ravenelii…a superb southeast native plant that’s almost unknown by native plant enthusiasts. In the wild, it grows in seasonally flooded ditches, but in the garden at JLBG, our plants thrive in typical garden soil with an average amount of moisture. Here are our plants flowering now…each filled with an array of pollinators.
The Pipevine Swallowtail butterfly caterpillars are munching away on any aristolochia (pipevine) in sight. This week, their favorite in the garden is the stunning Aristolochia fimbriata. Nature has created a wonderful balance where the catepillars each just enough to survive and grow, but not enough to damage the plant, which will quickly re-flush.
I noticed this odd soil formation in the garden this week and checked with our staff entomologist Bill Reynolds, who identified this as the nest of a Cicada Killer Wasp. These large, yellow banded wasps which we see around the garden, capture and paralyze cicadas, then bring them back to their in-ground lairs. The wasps drag the stunned cicadas into the mound and proceed to lay eggs in their paralyzed bodies. The eggs, then hatch and use the cicadas for food, eating the non-vital body parts first, so their food source remains alive as long as possible. When the hole is full of cicada bodies (generally less than a dozen), the wasps seal up the entrance, leaving no trace of what’s going on underneath. Sounds like a real-life zombie storyline.
Bees, birds, butterflies, bats and beetles are pollinators essential to sustain our ecosystem and food supply. Help preserve and celebrate the pollinators in your life.
With summer getting ready to begin, there are many plants that are at their peak and the pollinators are working tirelessly! Join our garden curator, Amanda Wilkins, this Saturday, June 22 from 10am-noon, for a personally guided tour of Juniper Level Botanic Garden. Take in the scents and vibrant colors of the late spring/early summer garden as the summer solstice begins. Register now!