This section is from the book "Wild Flowers East Of The Rockies", by Chester A. Reed. Also available from Amazon: Wild Flowers East Of The Rockies.
A small family composed chiefly of poisonous tropical plants, usually with milky, acrid juices. They have perfect and regular, five-parted flowers and opposite, smooth-edged leaves.
Indian Hemp (Apocynum Cannabinum) is a rather unattractive species with a smooth branching stem, rising from vertical roots to heights of 1 to 4 feet. The ovate-pointed leaves are lusterless, have very short stems and are closely crowded on the stalk oppositely to one another.
The small, five-parted, greenish-white flowers grow. in terminal clusters. A tiny drop of nectar, secreted at the bottom of each small, shallow cup, furnishes food for quantities of insects, including a great many crawling ones that are of no value to the plant. The name of Indian Hemp has its origin because Indians formerly used the tough fibres as a substitute for hemp in their basket work. We find this species very abundant in dry fields and thickets throughout our range; it flowers from June to August.
A. Indian Hemp.
Apocynum cannabinum.
B. Spreading Dogbane.
Apocynum androsaemifolium.
Spreading Dogbane (Apocynum Androsaemi-Folium) is a much more attractive species than its relative, just mentioned. It grows from 1 to 4 feet high, and has many long, spreading branches. The short-stemmed, broadly ovate-pointed, pale green leaves grow oppositely, to the ends of the branches, the leaves are all approximately in the same plane, that is, each succeeding pair does not appear at right angles to the pair before it, as is usually the case. The clusters of flowers terminating the branches are composed of pink, bell-shaped blossoms, having five, pointed, recurved lobes; they are veined with deeper pink and are fragrant. It is adapted to, and largely dependent upon butterflies for the quickening of its seeds. Common on borders of fields or thickets within our range.
 
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