Asclepias tuberosa L. - Butterfly Milkweed
Family - Asclepiadaceae
Stems - To +/-60cm tall, erect or ascending, herbaceous, hirsute and also with vertical lines of hairs from leaf bases, (the hairs small and curled), typically simple but branching near apex, from a woody crown.
Leaves - Mostly alternate but sometimes opposite by inflorescence, dense on the stems, short-petiolate. Petioles to 3mm long. Blades linear-oblong to linear-lanceolate, entire, acute, truncate at the base, often with slightly revolute margins, pubescent above, more so below, green above, lighter green below, to 10cm long, +/-2.5cm broad.
Inflorescence - Terminal and axillary umbellate cymes with +/-25 flowers. Pedicels subtended by linear bracts to 1cm long, 1.2mm broad. Pedicels +/-2cm long, with antrorse pubescence, light green.
Flowers - Petals 5, orange, reflexed, 8-9mm long, 2.2mm broad, glabrous, acute. Hoods orange, glabrous, 5-6mm long, 1.5mm broad, distinct. Horns to 3mm long, orange. Column 3mm long(tall), greenish. Pollinia 2mm long, translator deep purple. Pistils 2, 2.1mm long, with a few antrorse hairs at apex. Follicles erect, to 15cm long, 1.5cm wide, pubescent. Seeds oval, to +5mm long, with coma.
Flowering - May - September.
Habitat - Prairies, glades, open woods, disturbed sites, waste ground, roadsides, railroads. Also cultivated.
Origin - Native to U.S.
Other info. - This plant
is used much by gardeners wishing to attract butterflies to the area.
The flowers produced copious amounts of nectar and the plant itself is eaten
by the larva of Monarchs (Danaus plexippus) which
indeed belong to the group of butterflies known as the "Milkweed Butterflies",
family Danaidae. The butterflies store the cardiac
glycosides produced by the plant and hence become distasteful and even
dangerous to predators.
Photographs taken off Hwy 106, Shannon County, MO., 6-6-03 and at Devil's Well, MO., 6-27-03, and off County Road 2010, Lawrence County, MO., 6-16-05.