Asclepias hirtella (Pennell) Woodson

Asclepias hirtella plant

Family - Asclepiadaceae

Stems - To +1m tall, densely pubescent in upper 1/2, sparse pubescent to glabrous below, herbaceous, simple, erect to ascending, from a thick taproot, with milky sap, often reddish in strong sun.

Asclepias hirtella plant

Leaves - Alternate, short-petiolate, dense on stem. Petiole to 7mm long, scabrous. Blade linear-lanceolate, entire, to +13cm long, 1.5cm broad, scabrous on margins and midrib. Margins thickened and often reddish.

Asclepias hirtella leaves

Inflorescence - Axillary umbellate cymes with +/-60 flowers. Peduncles dense pubescent. Pedicels hispidulous, to +/-1.5cm long in flower. Cymes subtended by linear bracts to 6mm long. Bracts pubescent.

Asclepias hirtella inflorescenceInflorescence.

Flowers - Petals 5, reflexed, to 5mm long, 1.5mm broad, glabrous or very sparse pubescent, greenish white and purplish at apex. Anther head 3mm long(tall), 2.2mm in diameter. Pollinia 1.4mm long. Hoods 2.1mm long, whitish with purple tinge at base, appressed and attached to column for most of length. Carpels 2, 2.1mm long, glabrous. Sepals 5, reflexed, ovate, 2.1mm long, 1.2mm broad, hispidulous externally, glabrous internally, reddish at apex. Follicles fusiform, erect, to +12cm long, +/-1cm in diameter, pubescent. Seeds to 9mm long. Coma whitish, to +3cm long.

Asclepias hirtella flowerFlower close-up.

Flowering - May - August.

Habitat - Prairies, glades, and pastures.

Origin - Native to U.S.

Other info. - I placed this species in the white flowers section of this site because from a distance the entire inflorescence has a whitish appearance. Close up, however, the flowers have a definite purplish-green tinge. This species is easy to ID in the field because of its stout pubescent stems, many flowered inflorescences, and linear lanceolate leaves (which are alternate). The plant is common throughout most of the state except for apparently some areas of the Ozarks.

Photographs taken off Hwy 126, Barton County, MO., 7-4-03, and in Wayne Fitzgerrell State Park, IL., 8-3-05.


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