Asclepias syriaca  tuberosa

(ass-cle' pee-as)

Common name: Milkweed

Family: Apocynaceae, dogbane

Height x width: 2-4' x 1-2' depending on species

Growth rate: slow to fast

Foliage: opposite or alternate, broad oblong unless noted narrow; generally a milky sap when cut or bruised unless noted for one species

Flowers: terminal or drooping umbels as noted, pinkish purple to white to orange depending on species; summer followed by tapered pods in late summer which split open lengthwise to reveal many seeds with silky hairs for wind distribution; individual flowers are unique in having 5 recurved petals and a central crown divided into 5 parts

Hardiness: zones 3-9

Soil: dry and infertile

Light: sun

Pests and Problems: aphids, rusts and leaf spots may be seen but are not serious

Landscape habit, uses: meadow gardens (they compete well with grasses but not with tree roots), borders, butterfly gardens

Other interest: mostly native to eastern North America; genus is named for Aesculapius, the Greek God of medicine, as it has long been used to treat many ailments; Native Americans chewed the roots of tuberosa to cure pleurisy and other respiratory ailments, hence the other common name for this species of Pleurisy Root; the species syriaca contains cardiac glycosides, similar to the use of digitalins in treating heart disease, which when absorbed by monarch butterfly larvae  makes them toxic to predators; genus and related vining genera are sole source of food of the monarch.

Other culture: will not tolerate wet soils; taproot resents disturbance; slow to emerge in spring so take care when cultivating; easy once established

Propagation: seeds sown fresh, terminal or root cuttings


Many species are tropical including the bright red-orange, zone 9 curassavica (Blood flower). Of the following, those marked * are most commonly seen, with incarnata and tuberosa most common in commerce.
Species height flowers foliage, other
amplexicaulis, Blunt-leaved M. 1-4' dull purple, terminal leaves clasp stem, wavy margins
exaltata, Poke M. 2-6' creamy, drooping oval, paired
*incarnata, Swamp M. 1-4' purplish, terminal opposite, narrow, lanceolate
purpurascens, Purple M. 2-6' purplish red, terminal opposite, downy below
quadrifolia, Four-leaved M. 1-2' pale pink, terminal lanceolate, mid leaves whorled
rubra, Red M. 1-4' purplish red, terminal opposite, wet coastal areas
speciosa, Showy M. 2-6' drooping pinkish clusters as below only unbranched
sullivantii, Sullivant's M. 1-4' dull purple, terminal leaves almost stalkless
*syriaca, Common M. 2-6' drooping pinkish clusters opposite, downy below
*tuberosa, Butterfly Weed 1-2' bright orange, terminal alternate, watery sap
variegata, White M. 1-3' white/purple, terminal opposite, dark above, pale below
verticillata, Whorled M. 1-4' greenish, upper axils very narrow in whorls of 3-6
viridifolia, Green M. 1-3' green, upper axils thick, paired or alternate, wavy



Species are most often found in commerce, although the following may also be occasionally seen.
Cultivar species flowers other
'Cinderella' incarnata rosy-pink larger flowers, compact heads
'Gay Butterflies' tuberosa yellow/orange/red 2-3'
'Hello Yellow' tuberosa bright yellow 2-3'
'Ice Ballet' incarnata white 3-5', vigorous, long bloom


©Authored by Dr. Leonard Perry, Professor, University of Vermont as part of PSS123 course.

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