Near my house, next to the road the ground is sandy with a scattering of pebbles in the mix. Like much of Vermont what is not bedrock is ground up glacial debris deposited when the vast continental glaciers melted away. The ground is sandier than most places at my house because I am perched on the southern slope of a small rock outcrop, a place where the downward pressure of the glacier was lighter, water flowed under the ice, and fine sediment was deposited.
In that sandy ground there are wild strawberries, mosses, dandelions, fleabane, hay scented ferns, a few coneflowers, some potentillas, Allegheny blackberry, a little bracken fern, and a small stand of dogbane (Apocynum cannabinum) with delicate pink flowers.
Before moving to Vermont my only experience with this plant was via books. I always wondered why it was called Dogbane. Was it like negative catnip for dogs? Or was it simply toxic to dogs? Apparently it is a toxin, and not just to dogs. Ingestion of any portion can induce cardiac arrest and both the family and genus name literally translate to, “Away Dog!” Apocynum cannabinum has, thick, milky sap, much like a milkweed, indeed Milkweeds (Asclepiadoideae) are now considered to be a subfamily of the Dogbanes (Apocynaceae). Other members of the Dogbane family include two of my least favorite plants, Oleander and Vinca, both from the Mediterranean and common in California where they were introduced as ornamentals. Oleander can be seen in any urban environment in Southern California, most often as a highway divider plant. The sap is extremely toxic, raising painful rashes, and the smoke can be lethal if inhaled. Vinca, more commonly known as periwinkle, is common in Northern California where it invades riparian areas, covering both ground and small trees in a dense, vining mat of glossy green leaves studded with pretty blue flowers. It is nearly impossibly to eradicate once in place.
In the past some Apocynaceae species were used to make a poor quality rubber, others for toxin to apply to arrows. Some species produce edible fruit and others edible flowers. We extract heart drugs from a few of them as well.
The dogbane in my yard, Apocynum cannabinum, is a traditional North American source for extremely strong fiber, hence the “cannabinum ” species name, referring to the hemp-like characteristic of the plant. Common names run from simply Dogbane, to Indian Hemp, Wild Cotton, and Hemp Dogbane. The fibers are stripped from the stalk in late fall and can be twisted into a fine, strong cord. Cords made from dogbane were prized for their great strength and used for sewing, fishing lines, and other work requiring fine cordage.
The Hemp Dogbane ranges from calf high to chest high. The ones in my yard top out at waist high. The have an odd branching structure, perhaps best described as irregular opposite. The main stalk continually divides in a binary fashion, with one side acting as a dominate leader, this pattern is often repeated on the side branches, but in some cases buds on both side of the stem will form side branches instead. The result is a roughly Y shaped plant that rapidly spreads as it grows.
The leaves are opposite and the undersides are covered with a fine pubescence. I expect that the hairy leaves are an adaptation to help cope with moisture stress. Plants often evolve this trait to create a boundary layer of trapped, still air that aids in preventing moisture from being blown away. The upper leaf surfaces have a matte waxy texture, a little like nasturtium leaves. Water beads and runs off of them rapidly.
The seeds are held in long, horn-like pods. This time of year few of the seed pods have developed, but a couple of plants are a little further along in the cycle than others.
Few of the leaves have any insect damage, but the flowers are popular with a number of insect species. I’ve seen ants, flies, bees, and moths going to them. Hidden amongst the flowers are predators as well. The Goldenrod Crab Spider (Misumena vatia) seems fond of my dogbane.
Goldenrod Crab Spiders are so called because they often hide amongst the bright yellow flowers of goldenrod, a common meadow plant in New England. The spiders change color from white to yellow and back again based on input from their eyes. The yellow color seeps up to stain their carapace, providing camouflage. When they move to a pale flower the production of this pigment stops and the spiders slowly turn white once more. Experiments show that the spider will not change color if it cannot see what color plant it is on.
These are not web building spiders, they are ambush hunters, grabbing unsuspecting prey in their wide arms.
The smell of the flowers is odd and difficult to describe, incorporating many scents including a dusty sweetness and a faint rankness like dried meat on the edge of going bad, but they are pretty.