Plants with milky juice; sepals usually 5; corolla tubular, 5-lobed; stamens usually 5, inserted on corolla tube and alternate with the lobes; ovary superior; fruit mostly of 2 spreading follicles.
Blue Texas Star. Texas Dogbane. Blue-Star (_Amsonia texana_) belongs to a group named in honor of Charles Amson, a colonial physician. The stems are usually unbranched, 8-12 inches high, and are covered with narrow linear leaves. Like that of other amsonias, the tubular throat is lined with white hairs. The name of twin-pods might be given to the amsonias. The numerous seeds are borne in two narrow, erect pods which are united at the base and split along the inner sides. The pods are 3-4 inches long. The plant is perennial, growing in low clumps on limestone hillsides of Texas. The plants in North Texas form a conspicuous bluish-green line on low hills, when the flowers bloom in late March and April.
The oleander, periwinkle, and vinca are well-known members of the dogbane family. They all have a milky sap which is quite poisonous in the oleander, Indian hemp, and others. “Bane” is the common word in Northern Europe for “murderer” and is applied to poisonous plants.
Leaves usually opposite or whorled; sepals 5; petals 5, usually reflexed and with a 5-lobed crown; stamens 5, the pollen united into 1 or 2 waxy masses in each sac; carpels 2, free except for the united disk-like stigma.
Green-Flowered Milkweed. Silkweed (_Asclepiodora decumbens_) is a widespread plant from Arkansas to Utah and Northern Mexico. It is found on the central and western plains, blooming in early spring and sometimes again in the fall. The stout, leafy stems, topped by the ball-shaped heads of flowers form conspicuous clumps about a foot high. The flowers have a sweet nectar which draws many insect visitors. They bloom in April and early May, and the large warty pods mature in a few weeks. As the seeds bear a tuft of hairs at one end, they are easily scattered by the wind and other agents. It is one of the first plants to appear on burned-over areas.
The milkweeds get their name from the bitter milky sap. The flowers are quite different from other flowers in that there is a crown between the petals and the stamens. In many the pollen is borne in two pear-shaped masses with a thread-like connection. In the green-flowered milkweed, purple hoods are attached to the crown and hang over the pollen-sacs.