Asclepias tuberosa
Asclepias tuberosa, the butterfly weed, is a species of milkweed native to eastern and southwestern North America. It is commonly known as butterfly weed because of the butterflies that are attracted to the plant by its color and its copious production of nectar. It is also a larval food plant of the queen and monarch butterflies, as well as the dogbane tiger moth, milkweed tussock moth, and the unexpected cycnia. Because of its rough leaves, "A. tuberosa" is not a preferred host plant of the monarch butterfly but caterpillars can be reared on it successfully. Further, it is  one of the very lowest "Asclepias" species in cardenolide content, making it a poor source of protection from bird predation and parasite virulence and perhaps contributing to its lack of attractiveness to egg-laying monarchs. Description. It is a perennial plant growing to tall, with clustered orange or yellow flowers from early summer to early autumn. The leaves are spirally arranged, lanceolate, 5–12 cm (2" to 5") long, and 2–3 cm (about 1") broad. Some wild plants have been reported to have orange flowers that are very reddish. It is uncertain if this is due to soil mineral content, ecotype  genetic differentiation, or both. A cultivar, "Hello Yellow", typically has more yellowish flowers than ordinary examples of this plant. Distribution and habitat. This plant favors dry, sand or gravel soil, but has also been reported on stream margins. It requires full sun. Identification. The plant looks similar to the lanceolate milkweed ("Asclepias lanceolata"), but is uniquely identified by the larger number of flowers, and the hairy stems that are not milky when broken. It is most commonly found in fields with dry soil. Propagation. Most easily propagated by seed. The primary pollinators are bees and wasps, rather than butterflies. Sown  outdoors after frost, a plant will flower and produce seed in the third year. It is difficult to transplant once established, as it has a deep, woody taproot. Monarch Watch provides information on rearing monarchs and their host plants. Efforts to increase monarch butterfly populations by establishing butterfly gardens and monarch migratory "waystations" require particular attention to the target species' food preferences and population cycles, as well to the conditions needed to propagate and maintain their food plants. For example, the seeds of "A. tuberosa" and some other milkweeds often need periods of cold treatment (cold stratification) before they will  germinate. To protect seeds from washing away during heavy rains and from seed–eating birds, one can cover the seeds with a light fabric or with an layer of straw mulch. However, mulch acts as an insulator. Thicker layers of mulch can prevent seeds from germinating if they prevent soil temperatures from rising enough when winter ends. Further, few seedlings can push through a thick layer of mulch. In cultivation in the greenhouse, plants can easily be grown from seed to flowering in as little as three to six months. Common names. Common names include butterfly weed, Canada root, chieger  flower, chiggerflower, fluxroot, Indian paintbrush, Indian posy, orange milkweed, orange root, orange Swallow-wort, pleurisy root, silky swallow-wort, tuber root, yellow milkweed, white-root, windroot, butterfly love, butterflyweed, and butterfly milkweed. Toxicity and uses. The plant contains toxic glycosides, alkaloids and resinoids. These can cause weakness, seizures and corneal injuries. Native Americans and European pioneers used the boiled roots to treat diarrhea and respiratory illnesses. The young seed pods were used as food after being boiled in several changes of water. The seed pod down was spun and used to make candle wicks. Use of the plant is contraindicated  in pregnancy, during lactation or with infants due to its toxins, which include resinoids and pregnanes. Because monarch butterflies do not favor it when reproducing, it is not as suitable for use in butterfly gardens and monarch waysides as are other milkweed species.