It’s Complicated…

You may already know that monarch butterflies need milkweed. But did you know that milkweed does not need monarchs? Milkweed is not pollinated by monarch butterflies!

Monarchs have long skinny legs, and even longer skinny tongues. They have learned, over eons of co-evolution with milkweed, to avoid the dangerous sticky sap of milkweed by carefully alighting on the sides of the flowers and lowering their long “tongues” (proboscises) into the flower to reach the sweet nectar.

Monarch sips nectar while perching on the sides of milkweed flowers

As they drink, monarchs are careful to not put their feet down inside the flowers where they might get stuck. Unfortunately for the milkweed, this means that monarchs don’t pick up milkweed pollen! The pollen is held in specialized structures inside the upper portion of the flower called “pollinia.” For pollination to occur, pollen from the pollinia has to reach the flower’s stigma, deeper inside the flower. Without successful pollination, no seeds develop, and milkweed does not reproduce.

Microscopic view of milkweed flower — pollen is held on the two yellow leaf-like parts on the right, called “pollinia”
Graphic: Rick Darke

So, if not monarchs, who pollinates milkweed? It’s not any of the other butterfly species that also visit milkweed flowers without picking up pollen. Honeybees can’t do it. They are native to Europe where milkweed isn’t native, and they are too small to be strong fliers. If they go deep enough into milkweed blossoms to reach the pollen, they can be trapped, which is not good for either the bee or the milkweed.

Milkweed needs a strong flier, with stout hairy legs that will go down into the flower, catch the sticky pollinia, and carry pollen from one flower to the next. Luckily, nature has provided just the right insect for the job: carpenter bees!

Carpenter bee with its feet in milkweed blossoms
Photo: Pixabay

Carpenter bees (Xylocopa spp.) are the most important pollinators of milkweed. Their legs are heavy and hairy, so they can step right into the flower and come out covered with sticky pollinia. They are strong fliers, so they do not get trapped, and they can carry the excess baggage. As the carpenter bee goes from flower to flower, pollen is dispersed, flowers are pollinated, seeds form, and milkweed is reproduced.

Pollinia, shaped like little yellow leaves, cling to the hairy legs of the bee
Photo: Polinizador’s Blog

Recently, friends who were developing a new pollinator garden for a historic property commented on the trouble they were having with carpenter bees burrowing into the eaves of the historic building. They said that exterminators had tried several applications of pesticide over the years, but the bees were nesting once again in the wooden structure.

Only later, when we learned of the connection between carpenter bees and milkweed, did we realize the contradiction! If we plant milkweed for monarchs in a pollinator garden, but then try to kill the carpenter bees nesting in the eaves of the house, we are pulling a thread in the complex web of life that can unravel the whole thing! If we kill carpenter bees, milkweed disappears. If milkweed disappears, so do monarchs.

When we try to pick out anything by itself, we find it hitched to everything else in the universe.

John Muir, Naturalist

So, what to do about carpenter bees? Well, they prefer to move into holes or cracks that are already established. They apparently don’t like the smell of citrus, and they don’t care for white paint. So, instead of pesticide, try filling existing holes and cracks or replacing weak structures. Apply citrus oil, or maybe re-paint. But killing them? They are definitely hitched to everything else in the universe.

Carpenter bees are very efficient pollinators of many other flowers as well

So, it is complicated. Nature is complicated. The more we learn, the better we understand the profound relationships among living things that co-evolved over millennia.

But that doesn’t mean it is difficult to do the right thing. If we simply start with the maxim “do no harm,” we can make better choices. Before we kill a “pest,” let’s understand that creature’s role in the world. Let’s avoid pesticide, apply fewer chemicals, plant native plants, plant more plants, allow a little mess for habitat, live and let live.

For more information on the complex relationship between milkweed and the insect world, see the post “ Marvelous Milkweed-Not Just for Monarchs!” linked here.


A Small Wonder That Makes Us Wonder

There is a fascinating little plant, just emerging now in the early days of spring, that is a marvel of evolution. It is also one of our favorite native ground covers for shade.

Asarum canadense, Wild Ginger, is native to shady forests from Northern Canada all the way south to Georgia and west to the Dakotas. It has beautiful leaves that grow in pairs like rounded hearts. It grows very close to the ground, never more than 3 or 4 inches high, and it forms lush mats that densely cover a slowly expanding area. It spreads about 6 inches in each direction every year.

Wild Ginger and Trout Lily hug the ground in a shady spot

Underneath the pretty leaves, Wild Ginger hides its secret flowers. There are lots of flowers, but you have to get down low and push aside the leaves to find them. The flower stems and leaf stalks (petioles) are covered with downy hairs that give them a furry appearance. The flowers are purplish brown, with 3 pointed petals that open to a little cup where the stamens with pollen are hidden.

Wild ginger flowers hide under the leaves
Stamens with pollen are tucked inside the flower

Botanists believe that Wild Ginger evolved with its flowers right next to the ground to attract early-season flies as pollinators. Flies emerge from the ground looking for carrion. They promptly find the brownish flowers of Wild Ginger right on the ground and crawl inside. There they hide from rain and the cold nights of early spring, snuggling into the cup-like flowers and accidentally collecting pollen on their bodies that will be transferred to the next flower they visit.

Seeds develop in the pollinated flowers, and when they ripen, they are discovered by ants. The seeds have oily little appendages that are nutritious and delicious to ants who carry them off to their colonies. The ants eat the oily part, but abandon the seeds to germinate. Not only are the seeds protected this way from seed-eating animals, but they are effectively planted by the ants.

Wild ginger growing under a cherry tree
Did ants carry Asarum seeds up into the crook of the tree?

Wild Ginger is in the same botanical family, Aristolochiacea, as our native Pipevine, the host plant for the gorgeous Pipevine Swallowtail butterfly, and many experts believe that Wild Ginger is an alternate host plant for the Pipevine Swallowtail caterpillar.

Wild ginger does indeed taste like ginger, though eating much of it may be toxic and is not recommended. Indigenous Americans dried the tubers and ground them as a spice. Early colonists boiled the tubers with sugar water, making something like candied ginger and then used the cooking liquid as a syrup. Both groups used the plant as a poultice to treat wounds, and modern research has confirmed the presence of two antibiotic compounds in the plant.

Today, we know Asarum canadense best as a fantastic shade ground cover. It preserves soil moisture and suppresses weeds all summer. It is deciduous, so it uncovers bare ground for the winter, which benefits ground-nesting native bees, flies, and beetles. As a garden plant, it is absolutely gorgeous in combination with ferns and shade-loving grasses. It is ideal under trees and shrubs, as well as in wooded areas, and eliminates the need for mulch. Deer completely ignore it.

Wild Ginger with Maidenhair Fern and Bunny Blue sedge

So, this amazing plant evolved offering shelter to the little flies that pollinate it, feeding the ants that protect and distribute its seeds, and hosting caterpillars that turn into beautiful butterflies that pollinate other plants. It healed the wounds and spiced the food of the earliest humans on this continent. It is beautiful, and perfectly adapted to our climate. It is not difficult to grow, and it does exactly what we want our ground covers to do. It belongs here in every sense of the word. Wild Ginger is a perfect example of the benefits of native plants.

Why, then, do we see so much pachysandra, ivy, vinca, wintercreeper, and other non-native ground covers escaping suburban yards to infest our woodlands, suppress native plants, diminish food sources, and even pull down our trees? Why would we choose those imported plants when the perfect plant always has been right here?

We can’t help but wonder.

Pachysandra and vinca destroying forest

The Redbuds Are Coming!
The Redbuds Are Coming!

Long before Paul Revere made his historic ride, Redbuds were alerting everyone to the arrival of spring.

The Eastern Redbud (Cercis canadensis) is a small understory tree that shares the dappled edges of woodlands with two other American classics – Amelanchier and Flowering Dogwood, both featured here in earlier posts. Amelanchier (Serviceberry) is the first to bloom, followed by Redbud, and then Flowering Dogwood. If you are looking for a small flowering tree, skip the invasive Callery (Bradford) pear, take a pass on the Asian cherries, and go for one of these historic native beauties.

Redbud announcing spring at the Nature Center

Redbuds are unusual in that the flowers emerge along the branches, stems, and even the trunk of the tree. The flowers range from soft pink to deep fuchsia, and sometimes even in white. The tree is in the legume family and the flowers do look like pea blossoms. Long-tongued bees, like carpenter bees, reach deep into the flowers to sip nectar and emerge covered in pollen. The seeds are encased in something like pea pods and may remain on the tree all winter.

Redbud flowers emerge directly from the wood
Flowers may sprout even from the tree trunk

The leaves of Redbuds are large, somewhat shiny, heart-shaped, and are the host for Henry’s elfin butterflies. Perfect for smaller properties, the trees rarely exceed 25 feet in height. They have a rounded shape and look pretty even in winter. Fall color typically is not spectacular, but one recent introduction, ‘Forest Pansy,’ has beautiful purple leaves that turn deep red in the fall. And there is an interesting weeping form called ‘Lavender Twist’ that resulted from a natural mutation that has since been propagated by horticulturists.

‘Lavender Twist” Redbud
Redbud in full summer leaf at the Nature Center

The flowers of the Redbud are edible – either fresh, boiled, or fried. Native Americans ate the flowers, and also used the dried bark of Redbud as a spice. The seeds are edible, too, when roasted.

Spring salad garnished with Redbud and Violet flowers

Our local Redbuds, Cercis canadensis, evolved in the forests of the Eastern US, from southeastern New York to parts of Florida, and are hardy in zones 4 to 9. They are understory plants that grow in shade, but they flower best with more sun. They are happy in average garden soil and are well-suited to suburban yards. There are related species of Redbuds native to the dry heat of Texas, Nevada, and California that will survive in zones 8 and 9.

Redbuds really do have a connection to colonial US history. George Washington wrote in his diary about his particular interest in Redbuds. His initial preference for European plants was fading, and he became increasingly interested in indigenous American plants. He collected Redbud seeds from local forests and planted trees he grew from seed on his own property, no doubt increasing the popularity of our native tree.

A mother robin nested in a Redbud at the Nature Center

So, hear hear! The Redbuds are coming!


Can Your Ground Cover Do This?

Spring is happening, and one of our favorite native ground covers is ready to impress.

Packera aurea (formerly classified botanically as Senecio aureus) is also known by the common names Golden Groundsel, Golden Ragwort, and Butterweed. It’s hard to think of a ground cover that can match Packera for flower power. In April, it sends up flower stalks that stand 12 to 24 inches above the heart-shaped leaves. By early May, it bursts into bloom with bright yellow daisy-like flowers that last up to two months. It is simply stunning!

Packera just starting to bloom in April
The full razzle-dazzle at the Nature Center in May

When the bloom finally finishes, you can cut back the flower stalks or leave them standing. Allowing the seeds to ripen and fall will keep the plant colony fresh. The bright green leaves of Packera form a weed-suppressing mat that looks good all summer and well into the fall. Packera is vigorous, spreading by shallow runners, and will fill in quickly where it is happy, but it is also easy to control. Transplanted divisions do well if you want to share extras with friends.

Packera in late June with flower stalks remaining

Packera is an effective and attractive ground cover even when it’s not in bloom. The foliage will fill in under shrubs and around tall perennials, but it can overwhelm shorter plants unless you trim it back. Packera is semi-evergreen, and will continue covering the ground throughout the winter, even under snowfall.

Looking good in late September
Packera is still mostly green in December

Hardy in zones 3 through 9, Packera’s native range extends from the upper Midwest throughout the Eastern US. It naturally occurs at the edges of moist woodlands and in wet meadows. It is happy in light shade or part sun, but it can take full sun as long as there is adequate soil moisture. It prefers rich acidic soil.

Packera is very valuable to native bees, especially to small cuckoo and halictid bees who benefit from its early supply of pollen and nectar. The plant is not at all attractive to deer. This time of year, you can find Packera for sale at good nurseries, native plant sales, and on line.

So, are you among the many in our region who use non-native ground covers like pachysandra, ivy, or vinca? If so, we just have to ask…

Can your ground cover do this?


A Most Gracious Host

Photo: Travis Brady

This week in Around the Grounds, we learn about the hostess with the mostest.

Amelanchier invites everyone into the garden, sets an elegant table, and makes sure no one leaves hungry. It is the consummate host plant.

Amelanchier (pronounced “amuh-lank-kee-yer”) is a small tree or multi-trunked shrub that will feed bees, butterflies, birds, woodland animals, and humans, all while looking beautiful. You may know it by one of its many common names: serviceberry, shadbush, shadblow, juneberry, wild plum, sugarplum, or saskatoon. While there is debate about the origin of some of these names, everyone agrees that it was called “shadbush” by settlers in New England because its early bloom time coincided with the spawning season of shad fish in northeastern rivers.

Amelanchier blooms in April, covering itself with delicate white flowers, and providing essential nectar and pollen for the first emerging bees. The elegant white blossoms are a welcome sight contrasting beautifully with evergreens. While the flowers remain, bees, butterflies, hummingbirds, and moths all come to visit.

The most common form of Amelanchier is a multi-trunked shrub or small tree
The single-trunked tree form can reach up to 30 feet, but remains open and airy

Leaves appear as the flowers fade, but Amelanchier never creates heavy shade. The leaves are narrow and open, so there is plenty of light for underplanting. A true host plant, Amelanchier feeds an estimated 124 species of caterpillar, including the Viceroy, the Striped Hairstreak, and the Red Spotted Purple. That hospitality makes Amelanchier a very appropriate addition to our Pollinator Garden.

Adult Red Spotted Purple Butterfly
Amelanchier right now in the Pollinator Garden at the Nature Center
Photo: Travis Brady

Our gracious host really sets a fine table in June when the berries appear. That’s when the common names “Juneberry” and “Sugarplum” make sense. Amelanchier berries are not only edible, they are delicious! About the size of blueberries, but delicately sweet like raspberries, Amelanchier berries can be eaten right off the branch or turned into a very fine pie – but only if you can get enough of them before the birds do. It seems that robins, blue jays, cardinals, and mockingbirds all are willing to eat the berries a day or two before we think they are ripe. And we have seen chipmunks and squirrels risking life and limb to climb way out on swaying branches to get their fair share. Most years, we humans only get a handful or two of berries.

Amelanchier berries ready for everybody
Get ‘em while they last!

Botanically, Amelanchier is complicated. The genus includes over 20 species with native ranges from Canada and Alaska across the entire northern US, with some species even in Arizona and Florida. The best garden varieties in the northern US are Amelanchier arborea and Amelanchier laevis, both found in the taller tree form, and Amelanchier canadensis, which is more typically the multi-trunked shrub form. All three are hardy in zones 4 – 9 and prefer conditions typical of woodland edges, light shade and moist, fairly rich soil. These and other Amelanchier species freely interbreed both in the wild and in nursery conditions, so natural hybrids are common and very difficult to tell apart. If you’re shopping, you can choose a single trunk or multi-trunked specimen, and take whatever the label says with a grain of salt. But you really can’t go wrong.

After all, a gracious host like Amelanchier never turns a guest away from the garden….