Cynanchum laeve (Michx.) Pers.

Cynanchum laeve plant

Family - Asclepiadaceae

Stems - Twining, climbing, herbaceous, often reddish, with milky sap, with villous pubescence in lines on the stems.

Cynanchum laeve stemStem at a node.

Leaves - Opposite, petiolate. Petioles to +7cm long, reddish-green. Blades typically glabrous but also variously pubescent, dark green with evident veining above, cordate, ovate, acute to acuminate or apiculate, to +/-10cm long, +/-8cm broad.

Cynanchum laeve leaf

Inflorescence - Axillary umbellate cyme with +/-30 flowers. Peduncles to 5cm long, pubescent. Pedicels to 1cm long, pubescent.

Cynanchum laeve inflorescenceInflorescence.

Flowers - Corolla deeply 5-lobed. Lobes whitish, 7mm long, -3mm broad, erect to spreading, glabrous. Corona of 5 appendages. Appendages white, erect, to 6mm long, expanded at base, tapering into 2 linear lobes at apex. Calyx 5-lobed. Lobes green with some purple, ovate-lanceolate, to 3mm long, sparse pubescent.

Cynanchum laeve flowerFlower close-up.

Cynanchum laeve flowerAgain.

Fruit - A large follicle, 10-11cm long, 4cm wide at widest point, teardrop-shaped, glabrous. Seeds winged, to +8mm long. Coma to 4cm long, white.

Cynanchum laeve fruit Follicle.

Flowering - July - September.

Habitat - Disturbed sites, along fences, waste ground, roadsides, railroads, thickets, open woods.

Origin - Native to U.S.

Other info. - Being from the Asclepiadaceae, this plant will "bleed" a white, latex-like secretion when pinched or bruised. Don't get this in your eyes nose or mouth as it can be irritating or harmful.
This plant is seen as a weed by some but it always dies back in the fall leaving the large fruits hanging until they split open dorsally. The seeds can be carried a great distance by the wind.
This species can be found throughout most of Missouri but is apparently absent from the south-central Ozark region.

Photographs in St. Louis, MO., 7-28-03.


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