Apocynum androsaemifolium L.

Spreading Dogbane

Apocynum androsaemifolium plant2

Family - Apocynaceae

Habit - Perennial herb, sometimes woody at base, with milky sap.

Stems - Ascending to erect, to 1.5 m, branched, glabrous, often glaucous, terete.

Leaves - Opposite, occasionally some subopposite or alternate, short-petiolate or sessile, the lower leaves typically drooping. Petioles to 5 mm. Leaf blades ovate to elliptic, to 9 cm, entire, the upper surface glabrous, the lower surface usually sparsely pubescent, rounded to angled and often mucronate at the tip, often somewhat asymmetrical at the rounded base.

Apocynum androsaemifolium leavesPressed leaves.

Apocynum androsaemifolium leavesFresh leaves.

Inflorescences - Terminal or axillary, branched loose clusters of few to many flowers. Flowers sweetly fragrant. Peduncles and pedicels glabrous. Peduncles to 4 cm long. Pedicels to 4 mm long in flower.

Apocynum androsaemifolium inflorescence2Inflorescences.

Flowers - Calyces glabrous, the lobes 1.5-2.5 mm long, ovate-triangular. Corollas 5-lobed, bell-shaped, 4-7 mm long, whitish to pink, with pink stripes on the inner surface, the tube 3-4 mm long, usually more than twice as long as the calyx, 4-5 mm wide at the tip, the lobes 2-3 mm long, spreading or recurved. Stamens 5, curving inward to form a cone over the stigma, the filaments 0.8-1.1 mm long, hairy. Anthers 2.5-3.2 mm long. Nectar glands 5, green, alternating with stamens. Pistils 2, green, glabrous. Styles 0.7-1.0 mm long, the ovoid stigma about 1 mm long.

Apocynum androsaemifolium flowers3Flowers.

Apocynum androsaemifolium flowers

Fruits - Follicles to 9 cm, pendent, slender, straight. Seeds numerous, 2-3 mm long, narrowly cylindrical, somewhat tapered toward the base, with a tuft of hairs at the truncate tip

Flowering - May - July.

Habitat - Dry open rocky woods, thickets, roadsides.

Origin - Native to U.S.

Other info. - This species is scattered and not very common in Missouri. It is far more common in the upper Midwest and in the western half of the U.S. When blooming it is easy to identify by its distinctive flowers, which have recurved lobes and pink internal stripes. The species has been subdivided, and according to this classification Missouri plants would be referable to var. androsaemifolium.

This species has the typical white milky sap of the Apocynaceae and can be toxic if eaten. Fruit set is usually low despite the great popularity of the flowers with flying insects. Traditionally the plant was used as an emetic and a diuretic. The strong fibers of the plant can be made into rope.

Photographs taken at Pictured Rocks National Seashore, MI., 7-12-02 (DETenaglia); also in Larimer County, CO, 7-10-2014, 7-30-2017, and 6-23-2018 (SRTurner).


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