A family of stout-stemmed plants having milky juices and ,usually, large opposite or whorled leaves. They all have umbels of small flowers that are very peculiar in construction and highly specialized for cross-fertilization by particular classes of insects. Each blossom has five tiny structures shaped like wish-bones, with pollen masses on each end. They are so placed that the visiting bee or butterfly is pretty sure of getting one or more of its legs caught in the sharp angle at the apex and must, in order to get free, tear the tiny arrangement from its support. He then flies to the next plant with this dangling from his legs. It is an unique method of forcing insects to work for it, but one that never fails as far as the plant is concerned, but sometimes proves a fatal trap for insects lacking the strength to tear away the tiny pollen saddle bags. We often find the corpses of several such insects hanging from the flower cluster, with their legs hopelessly entangled.
Butterfly-weed. Asclepias tuberosa.
Butterfly-Weed; Pleurisy-Root; Orange Milk-Weed (Asclepias Tuberosa) is the most brilliantly colored species of the genus. Even those accustomed to the sight of this plant cannot suppress the feeling of admiration that stirs them as they suddenly behold the vivid, orange flashes greeting them as they cross waste or dry fields.
The stem of butterfly-weed is usually erect, from 1 to 3 feet high; it is rather rough and has but little of the milky juices so common to the other species. The leaves are pointed-oblong, very short-stemmed or seated oppositely. The beautiful orange flowers grow in flat-topped clusters or umbels, at the summit of the plant. It is found from Mass. to Minn, and southwards, most abundant in the Southern States. Its roots are used medicinally.
Common Milkweed. Asclepias syriaca.
Common Milk-Weed (Asclepias Syriaca) is the most abundant and the best known of the Milkweeds. It grows everywhere along roadsides, in fields and on the borders of woods. The rather stout stem rises from 2 to 5 feet high and has numerous, opposite, large, oblong, short-stemmed leaves of a yellow-green color. Both the leaves and the stem are finely hairy and both yield quantities of a thick, sticky, bitter, milky fluid if they are broken or bruised anywhere. It has been found that the outer covering of the stem is extremely delicate and that the tiny, claw-like feet of insects that attempt to crawl up the stalk will cut through this covering sufficiently to cause the feet of such visitors to become sticky with the milky fluid; this not only discourages the would-be pilferers of the flowers' sweets but makes it quite impossible for them to reach the top of the long stem. Ants frequently become so gummed up with the sticky substance that it causes their death.
The flowers grow in rounded clusters often in a pendent position, from the axils of the upper leaves. They are very fragrant and secrete an abundance of nectar. They are visited by many varieties of bees and butterflies, by one of the latter so frequently that it is known as the Milkweed Butterfly (Anosia plexip-pus.)
In the Fall, the clusters of lilac-colored flowers have been replaced by large, rough-coated seed-pods that are completely filled with the silkiest of flossy substance attached to the numerous black seeds; finally the pod bursts and liberates the seeds, each floating away on the breeze, sometimes aviating for several miles before coming to earth. This provision for the spreading of the seeds results in a widely distributed, strong race, that is ever on the increase.
A. Poke Milkweed.
B. Narrow-leaved Milkweed.