Asclepias purpurascens L. - Purple Milkweed

Asclepias purpurascens plant

Family - Asclepiadaceae

Stems - Erect, herbaceous but stout, typically simple, from a taproot, with milky sap, pubescent and also with a vertical line of tomentoulose hairs decurrent from the base of each petiole, to +1m tall.

Asclepias purpurascens stemStem...

Asclepias purpurascens stem...again, with milky sap.

Leaves - Opposite, decussate, short petiolate. Petioles to -1cm long, antrorse pubescent. Blades to +20cm long, 8cm broad, entire, abruptly acute at the apex, abruptly tapering to a rounded base, often with a purple tinge on the midrib adaxially, pubescent and deep green adaxially, light green and densely pubescent abaxially. Lateral venation anastomosing.

Asclepias purpurascens leavesPressed leaves.

Inflorescence - Few axillary pedunculate umbels near the apex of the stems. Peduncles to +/-7cm long, erect, sparse pubescent but tomentoulose on one side. Flowers +/-50 per umbel. Pedicels to +/-2cm long, tomentoulose, subtended by linear bracts. Bracts withering quickly, to +/-6mm long, pubescent.

Asclepias purpurascens inflorescenceInflorescence.

Flowers - Petals 5, reflexed to spreading, purplish-pink, glabrous, to +1cm long, +/-4mm broad, acute, oblong-lanceolate, entire. Hoods purplish-pink, +/-7mm long (tall), glabrous, connected at the base below the anther column. Horns purplish-white, 2mm long, down-curved and converging at the apex of the anther column. Anther column mostly green (white at the apex), 3-4mm in diameter. Pollinia to -2mm long, the connective deep purple. Pistils 2, glabrous, light green, 3mm long in flower.

Asclepias purpurascens flowerFlower close-up.

Asclepias purpurascens flowerAgain.

Flowering - May - July.

Habitat - Rocky open woods, glades, prairies, stream banks, wet meadows and valleys, thickets, roadsides.

Origin - Native to U.S.

Other info. - This showy species can be found throughout Missouri. The plant is quite striking and would grow with little care in a garden. This species also attracts many flying insects and would be a great addition to a butterfly garden.
The stems of A. purpurascens produce copious amounts of milky sap when injured. This sap can be irritating to some and is toxic if ingested or rubbed in the eyes.

Photographs taken off Hwy 21, Reynolds County, MO., 6-1-03, and off Hwy 106, Shannon County, MO., 6-12-04.


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