Apocynum androsaemifolium, a flowering plant in the Gentianales order known by the common names fly-trap dogbane or spreading dogbane is seen at various spots in the San Bernardino Mountains.
Growing to a maximum of roughly two-and-a-half feet high, Apocynum androsaemifolium is a widely branching, bushy, perennial plant. The spreading dogbane’s leaf margin is entire and leaf venation is alternate, that is, with opposite, oval leaves. It sports small groups of tiny bell-shaped flowers that are white or pink externally and striped inside with deeper pink. The flowers appear terminally, i.e., near the branch tips.
The flowers’ fragrance is reminiscent of lilac. Apocynum androsaemifolium has branching stems, hairs on the underside of the leaves, and no hair on the stems. Milky juice exudes from broken stems and leaves.
The plant is poisonous, due to the cardiac glycosides it contains.
These plants are relatives of the milkweeds. Indian Hemp (A. cannabinum), a slightly smaller species with erect clusters of greenish-white flowers, is also found in fields and is poisonous. Clasping-leaved Dogbane (A. sibiricum), found widely throughout the Northeast in sandy or gravelly habitats such as stream banks, has stalkless or nearly stalkless leaves.
Spreading dogbane is a showy member of the dogbane family (Apocynaceae) that is found in nearly all of the 50 states except some in the southeast. The common name, dogbane, and the genus name, “Apocynum,” meaning “away from dog,” are testaments to the toxic nature of this plant, not only to dogs, but to humans, livestock, and other mammals as well.
The red stem branches multiple times, giving it a wide-spreading appearance. The leaves lining each branch droop down. The flowers are small, at just over a quarter inch wide. Each flower produces two slender pods that release numerous small seeds tipped by a tuft of cottony hairs that aid in wind dispersal. Spreading dogbane, as the name suggests, tends to spread from underground rhizomes and form distinct patches. Although it is native to North America, in some areas it is considered a nuisance weed.
Spreading dogbane is found in a variety of habitats, from native plant communities to weedy roadsides and waste areas. The flowers produce nectar that is an important food source for insects, most notably the monarch butterfly. In fact, the milkweed family, host plant for monarchs, and the dogbane family are closely related. Once thought to be a larval food for Monarch butterflies, research has shown that while adult female Monarchs will occasionally oviposit on this species, their offspring will not mature on it.
If you break a spreading dogbane stem or leaf, you will see that the plant contains a bitter, sticky, milky white sap. The sap contains cardiac glycosides that are toxic to humans. The root also contains a potent cardiac stimulant, cymarin. These toxic compounds help protect spreading dogbane from grazing animals. Despite its toxicity, the plant has been used medicinally for a variety of ailments. This plant is enjoyed for its beauty and is of limited utility as a medicine. Native Americans used the tough fibers of this and other native dogbanes to make threads and cord.