A. syriaca (common milkweed) is a perennial herb with long-spreading rhizomes. Stems stout, erect, to 2 m tall, with short downy hairs and milky juice;leaves opposite, smooth margined, oblong, 10-20 cm long and 5-11 cm wide, with prominent veins;upper surface smooth, lower covered with short white hairs. Flowers sweet-smelling, pink to white, in large, many-flowered (the number per inflorescence varies greatly, from less than 10 to more than 120) axillary and apical bell-like clusters. The long-lived flowers produce copious amounts of nectar (Wyatt and Broyles, 1994), flowering from June to August, depending on initial growth, climate, and location (Anderson, 1999). Seed brown, flat, oval, 6 mm long, 5 mm wide, with a tuft of silky white hairs apically. All plant parts contain latex;shoots from established plants arise from adventitious root buds, emerging in April and May. The root system is composed of horizontal and vertical roots. In established stands, vertical roots may penetrate the soil to depths of 3.8 m (Anderson, 1999).
Related invasive species
- Asclepias syriaca
Related Farm Practice
- Soil
A. syriaca can be an aggressive and persistent weed and contains several poisonous glucosidic substances (cardenolides) known to be poisonous to sheep, cattle, and occasionally horses (Anderson, 1999).
The crops most affected by this species are soybeans, corn, peanuts and grain sorghum (Anderson, 1999) and maize (Konstantinovic et al., 2008). Canadian studies of c ompetition between common milkweed and oats found up to 20% yield loss of grain (Bhowmik, 1982).