This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Native. Perennial. Propagates by seeds.
Time of bloom: June to August.
Seed-time: August to October.
Range: Anticosti to British Columbia, southward to Florida, Texas, and southern California.
Habitat: Moist soil; fields and thickets.
Nearly related to the Spreading Dogbane, quite as obnoxious, but lacking its beauty. This plant is valuable medicinally, and the roots, gathered in autumn, cleaned, and dried, bring eight to ten cents a pound in the drug market; the inner bark yields a fine and very strong fiber, but no commercial use is made of it.
Root deep, vertical, branching. Stems one to five feet tall, smooth, erect, with ascending branches. Leaves two to four inches in length, oblong, pointed at both ends or sometimes rounded at base, entire, pale green, smooth above, occasionally somewhat hairy beneath, those on the main stem having distinct petioles, those on the branches often nearly sessile. Flowers terminal (sometimes axillary) in rather dense cymes, held erect; calyx with five lobes, nearly as long as the tube of the very small, five-lobed,' greenish white corolla. Pods in pairs, similar to those of the Spreading Dogbane. (Fig. 219.) Means of control the same as for the preceding species.
Fig. 219. -Black Indian Hemp (Apocynum cannabinum).