Perennial herb 30 - 80 cm tall Leaves: opposite, erect or ascending, essentially stalkless (rarely with stalks up to 3 mm) with glands in or above the axils. The blades are 5 - 11 cm long, 1 - 5.5 cm wide, oblong to broadly elliptic or oval, with an abruptly pointed spine-tip, broadly rounded to indented or clasping base, non-toothed edges, and rarely any hairs. Inflorescence: of individually stalked, erect or ascending flowers in terminal, somewhat broad, branched clusters. The inflorescence clusters are typically surpassed in height by the leaves and lateral branches. Flowers: greenish white or pale yellow, 3 - 5 mm long, radially symmetric, cylindric to urn-shaped, and quite fragrant. Sepals: five, but fused at base, then separating into triangular, pointed lobes, which are over half the length of the petal tube. Petals: five, but fused for most of their length, then separating into short, mostly erect lobes, with the petals overall less than two times the length of the sepals. Inside, near the base of the petal tube, and opposite each lobe, is a tooth or scale. Stamens: five, with separate, short filaments attached to the inside of the petal tube, but the lance-triangular-shaped anthers fused together, surrounding and connected to the stigma, and prolonged beyond the stigma into a cone. Pistil: with two, superior ovaries, which are subtended by five nectaries, but the two ovaries sharing a single style and stigma. Fruit: of two, dry, single-chambered, many-seeded, 4 - 10 cm long, elongate, slender, somewhat straight, spindle-shaped (with narrowed ends), capsule-like pods (follicles), which open lengthwise by a single seam. Stems: erect or ascending, sometimes almost prostrate, often branched above, and usually with an obvious main axis. The always hairless stems are tough, fibrous, and exude a milky, acrid juice or latex sap when cut or broken. Seeds: numerous, 3.3 - 5.5 mm long, narrowly elliptic to sickle-shaped, with a conspicuous tuft of 1 - 2.5 cm long hairs (coma) at one end.
Similar species: Apocynum sibiricum is incredibly similar to A. cannabinum, but that species has evidently stalked leaves with tapered or rounded bases, and longer fruit (10 - 20 cm) that are also slightly curved. Also quite similar is the hybrid of this species and A. androsaemifolium, A. x floribundum, except the hybrid has pale pinkish flowers, inflorescence clusters that often surpass the foliage, smaller seeds (under 4 mm long), and stalked leaves. The third species in our area, A. androsaemifolium, is the least similar because it has larger flowers (0.6 - 1 cm long) on drooping stalks, the petals are obviously pinkish with spreading or recurved lobes, many of the stalked leaves droop, the inflorescences usually extend beyond the leaves, and the seeds are only up to 3 mm long.
Flowering: late May to late August
Habitat and ecology: Somewhat common, usually in disturbed sites such as along railroads or in old pastures, but also in other fairly open sites.
Occurence in the Chicago region: native
Notes: This species has often been treated as only a variety of A. cannabinum (A. cannabinum var. hypericifolium). However, the local floras as well as the most recent treatment of the flora of eastern North America (Gleason and Cronquist 1991) recognize both as separate species, as we do here. Hybridization is very common between this species and A. androsaemifolium. The flowers of our Apocynum species are very fragrant and attract many insects. According to Voss (1996), a particularly striking leaf-beetle, Chrysochus auratus Fabr. is often seen associating with species of Apocynum, and its larvae feed on the roots, thus it has been known commonly as the "dogbane beetle". Several species in the Apocynaceae family are used as sources of chemicals in medicine, or in poisons, and most members of the family are poisonous due to the presence of the milky latex sap. Native Americans were known to use the tough, fibrous stems of Apocynum for material fibers (Voss 1996).
Erect, branched above, 0.5-1.5 m, with a well developed main axis; lvs on short but evident petioles 3-10 mm, erect or ascending, 5-11 cm, oblong-lanceolate to oval or broadly elliptic, acute to rounded at the base and mucronate apex, glabrous or hairy beneath; fls erect; cal-lobes usually reaching beyond the middle of the cor-tube; cor cylindric to urceolate, 3-6 mm, white or greenish-white, the lobes erect or slightly divergent; fr (5-)10-15(-20) cm; coma mostly 1-3 cm; 2n=16. Open places; rare or local in e. Can. and N. Engl., abundant from N.Y. to N.D., s. to Fla. and Tex., and w. occasionally to the Pacific. May-Sept. Highly variable in lf-shape and pubescence.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Martin and Hutchins 1980, Welsh et al. 1993, McLaughlin 1993
Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Erect or ascending stems, reddish, glabrous but tough and fibrous bark, growing to 1 m tall, producing a milky latex. Leaves: Opposite or whorled, short petiolate above, sessile below, blades ovate to lanceolate, these 2-14 cm long and 1-7 cm wide, rounded at base but narrowed, mostly ascending, they are glabrous on the upper side and pubescent below. Flowers: In terminal cymes, these with small white flowers, these 5-parted cylindrical to urceolate corollas are 2-5 mm long, slightly longer to twice as long as calyx, lobes erect or slightly spreading. Fruits: Follicle slender, terete, 10-20 cm long, with many seeds each with a tuft of hair at one end. Ecology: Found on disturbed sites, especially along streams, roads, fields, but generally in mesic soils from 3,500-7,500 ft (1067-2286 m), flowers May-September. Distribution: Ranges north throughout the United States to Canada. Notes: This plant loves a variety of mesic habitats and can reproduce asexually through its roots, so it can be found in clumps. Ethnobotany: Used as a hair tonic, used to help mothers stimulate milk production, taken as a laxative, for rheumatism, coughs, pox, whooping cough, asthma, diarrhea, stomachache, as an eye medicine, for worms, and the root was used as a universal remedy. It also has ceremonial uses, the latex was used as a chewing gum, the seeds were eaten, and the bark can make cordage and a whole range of useful things. Etymology: Apocynum is from Greek apo, away from, and kyon dog, hence dogbane, while cannabinum means help-like. Synonyms: Apocynum hypericifolium, A. pubescens, A. sibiricum, A. suskdorfii Editor: SBuckley, 2011