Flower structure of the Asclepias purpurascens purple milkweed: Actually, all the milkweeds have similar structure. The flower has both male and female parts. It has a corolla that separates out to 5 petals and has a 5 parted calyx (sepals).

In the labeled photo below, inside the petals is a circle of 5 hoods each containing a horn. The hoods hold nectar which attracts insects. These hoods encircle the gynostegium. The gynostegium (whitish part in the center) is a column of partially fused stamens and the pistil. There are 5 stamens.

The anthers, in the gynostegium, are split in half with a slit between each half, called the stigmatic slit. Instead of individual pollen grains, the grains are together in a sac called the pollinium (pollinia - plural). There is a pair of pollinia inside of each slit connected to the corpusculum, the dark object. The translator arm connects the corpusculum to the pollinia. These three parts, corpusculum, translator arm & pollinia, together are callled a pollinarium.

Now for the female parts. In the gynostegium are 5 receptive stigmatic surfaces that are inside of 5 stigmatic chambers. Access to the receptive stigmatic surfaces is through the stigmatic slits. So both the pollen grains and the stigmatic surfaces are enclosed in the stigmatic chambers, with access only through the slits! Interestingly, each flower has two ovaries. Two stigmatic chambers are connected to one ovary and 3 stigmatic chambers are connected to the other ovary.

Another view of the horns that emerge from the hoods. Note that the incurved horns grow horizontally over and down toward the gynostegium (center whitish part). The color of the flowers and the horns distinguish purple milkweed from common milkweed. See common milkweed click here

The purple milkweed seed pods (follicles) are up to 6 inches long, wider at the base and coming to a point at the tip. They are smooth. Purple milkweed with its smooth follicles can be distinguished from the common milkweed that has prickly follicles.

Frequently, purple milkweed does not set seed!

The purple milkweed plant is a large upright perennial growing to 3 feet tall and at the top usually one or two flower umbells form. The stem is sturdy, pale green, and usually short-pubescent or smooth. The purple milkweed plant does not have a network of thick rhizomes (horizontal underground stems) for vegetative propagation like the common milkweed, Ascepias syriaca. The root system of purple milkweed consists mainly of a stout fleshy taproot. Consequently, purple milkweed needs to rely more on seeds for propagation.

The leaves are simple, opposite and paired not whorled.

They are ovate-oblong (wider at the base and rectanglar with rounded ends) to elliptic (broadest in the middle). The leaves are about 6 inches long and 2 inches wide.

The upper surface is dark green and hairless while the lower surface is lighter green and hairy.

The leaf has a prominent midrib. The midrib may be red-brownish sometimes. The many smaller veins extending from the midrib to almost the edge have a distinctive pattern with the veins almost parallel to each other and perpendicular to the midrib.

The margins of the leaf are smooth but wavy (up and down).

Like other milkweeds, when the leaves or stems of purple milkweed are broken, they produce a milky latex. This liquid contain various levels of toxic cardiac glycoside compounds which makes the plants toxic to most insects and animals but not deer.