The wet prairie, descended from Pleistocene swamps and lakes, basically contains water-growing plants. In the succession of plant species, as the shallow lake filled with vegetation, there came the cattails, the sedges, the bur-reeds, which made it a swamp. When the tall plumes of Spartina grass appeared, this was the signpost indicating a change to wet prairie, and with it came an entirely different group of plants. For miles, long ago, the wet prairie with its waving Spartina, its bright prairie sunflowers and white indigo spikes, extended across much of Illinois. As part of it. in this peculiar association of plants, soil, and climate, were the stiff stalks of Sullivant's milkweed. Today, as yesterday, it is as much an indication of the wet prairie as the Spartina.
Asclepias sullivantii Engelm.
July. Prairie roadsides.
This is a stout, smooth milkweed which is distinguished from the common milkweed by having broad, blue-green leaves conspicuously veined with pink, with a great, thick, pink midrib. The stalk is smooth, pink and green-white, and bears the fluted leaves in stemless pairs along it. At the. summit are huge, globular clusters of typical milkweed flowers, but the individual blossoms are Larger than those of common milkweed. They have the typical live horns and recurving sepals - the latter deep rose, the former bright pink. The intricate and prominent veining of this milkweed, however, is one of its highlights and one of its chief distinctions. That, and the presence of the remnants of wet prairie, placarded by Spartina, where the splendid columns of Sullivant's milkweed are found.