Swamp Milkweed

Asclepias incarnata

Swamp milkweed, like all milkweeds, has very strange flowers.  The five petals are bent back and curve down below the flower like sepals; the true sepals are hidden behind them.  In swamp milkweed the petals are pink to red, but in other milkweeds they may be drab in color.  Above the petals once notices a little crown, known to botanists as the corona, which means "crown" in Latin.  The corona is formed from the stamens, or male parts.  In milkweeds, the stamens are fused together, and their stalks (called by botanists, the filaments) are fused into a tube surrounding the pistil or female organ.  Each anther has a cowl-shaped structure, called a hood, and each hood has a little protruding horn.  The five hoods and their horns make up the corona.  In swamp milkweed the corona is a pale pink, and the fused pistil and stamens are white.  All these parts can be seen in the flower closeup at lowest left.

The leaves of swamp milkweed are long and narrow, and arranged opposite each other on the stem.  The fruits are follicles, which is the botanical term for a pod that splits open on one side.  When it splits, it releases the seeds, which are attached to a cluster of soft hairs that catch the wind, lofting the seed away to a new location.  Oddly, only a very few of the many flowers will produce a fruit.
 

Most milkweeds in the genus Asclepias have thick, sticky, milky white sap, from which the name milkweed comes.  Nearly all parts of the plant bleed this sticky, fast-drying sap when cut or bruised.  The sap is bitter-tasting and generally poisonous.  It is believed that the bitter taste and sticky nature of the sap discourages any insect or other animal that might try to eat the plant.

Milkweed does not produce individual grains of pollen like most plants do.  Instead, the pollen is fused into waxy packets called pollinia.  Each stamen produces two pollinia connected by a thread.  The flowers are generally very fragrant and produce copious amounts of nectar.  This makes them very attractive to bees and butterflies which visit the flowers in droves.  The fused stamens have narrow slits between them into which a careless insect might accidentally insert a leg.  If it does, the leg will likely catch on the sticky thread connecting the pollinia.  When the insect withdraws its leg it will usually have the two packets of pollen attached, ready to be carried to another flower to pollinate the flower and fertilize its eggs.  Sometimes, however, an unfortunate insect will be unable to extricate its leg and will die trapped in the milkweed flower.  When you see a milkweed plant, look for these unfortunate insects.
 

Milkweed floss, the fuzzy hairs that attach to the seeds are used by birds in lining their nests.  They have been used by humans to stuff pillows, and, during World War II, the US government harvested large quantities of milkweed floss as a substitute for kapok in making life vests. 

All milkweeds are more-or-less poisonous.  They contain toxic compounds known as cardiac glycosides which interfere with heart function.  Very few insects can tolerate milkweed; those few that can have evolved not only resistance to the poison, but the ability to store it, becoming themselves poisonous and unpalatable to predators.  Milkweed bugs, milkweed beetles, and monarch butterfly caterpillars specialize in eating milkweeds and are consequently poisonous to birds and other insect eaters.  To make sure the birds know this, these insects are brightly colored in yellow or orange and black.  The adult monarch butterfly retains the poisons of its caterpillarhood and is also bright orange and black.  The flower nectar, however, is not poisonous and is popular with many species of  butterflies and bees.