syriaca 
tuberosa
Common name: Milkweed
Family: Asclepiadaceae, Milkweed
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
Species:
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 |
Cultivars:
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 |
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