Apocynum cannabinum L.

Apocynum cannabinum plant

Family - Apocynaceae

Stems - To 1m tall, glabrous below, pubescent or villous above, glaucous, purplish, branching above, erect, single from base, rhizomatous.

Apocynum cannabinum stem

Apocynum cannabinum stemStem with milky sap.

Leaves - Opposite, oblong to oblong-lanceolate, sessile or on short petioles, glabrous to variously pubescent, typically acute at tip, entire, to +10cm long, +4cm broad.

Inflorescence - Terminal and axillary dense cymes. Pedicels short, to -3mm long. Flowers each subtended by a small lanceolate bract to 2mm long.

Apocynum cannabinum inflorescence

Flowers - Corolla tubular, whitish to greenish-white, small, to 5mm long, 5-lobed, glabrous internally and externally. Lobes ovate to triangular, acute, spreading, 2mm long. Stamens 5, alternating with corolla lobes, included. Anthers orange, connate around stigma. Nectaries 5, alternating with stamens. Ovary of two carpels. Placentation parietal. Follicles to 20cm long, spreading or erect, typically slightly curved. Seeds with a coma.

Apocynum cannabinum flowerFlower close-up.

Flowering - May - August.

Habitat - Open woods, pastures, waste ground, disturbed sites, wooded slopes, roadsides, railroads.

Origin - Native to U.S.

Other info. - This species can be found throughout Missouri and is quite common. It can be identified in the field by its reddish stems, milky sap, opposite leaves, and small white flowers.
A. cannabinum is used as "Hemp", made from the twisted fibers of the plant. The species epithet means "Hemplike". Traditionally the plant was also used to treat a variety of ailments. The sap of the plant contains cardiac glycosides and is toxic in moderate to large doses. Some of the secondary compounds of the plant have shown antitumor activity.
Steyermark divides the species into two varieties. Variety cannabinum (pictured above) is basically glabrous throughout the entire plant. Variety pubescens exhibits pubescence on the leaves, stems, and calyx. Both are common.

Photographs taken at the Kansas City Zoo, 6-11-00, and in St. Louis, MO., 7-28-03.