Tom's Blog

Friday, August 22, 2014

Lots of milkweeds at Pleasant Valley Conservancy

The Monarch butterfly is a species of great conservation interest. The survival of monarchs is linked to milkweeds. Monarch caterpillars eat only milkweeds, and monarch females lay their eggs on milkweed plants. Because milkweeds are becoming scarce on the landscape, environmental groups are encouraging the planting of milkweeds. The easiest to plant and raise is the common milkweed, Asclepias syriaca. However, other milkweed species also support monarchs, as well as other butterfly species.

We don't need to plant milkweeds at Pleasant Valley Conservancy because our prairies and savannas support extensive native populations. The table below lists the seven species we have. The only one that is not native to the site is butterfly milkweed.

The most common milkweed at Pleasant Valley Conservancy is, of course, the common milkweed, which is the species that most conservationists are planting. This species establishes well and because it is clonal, it easily forms large patches. Also, it has a wide habitat tolerance, growing well in both prairies and savannas.

At Pleasant Valley Conservancy it does especially well in our oak savannas, and I estimated one clone in Unit 11C at almost an acre in extent.
Common milkweed

Purple milkweed, a State endangered species and one of the signature species at Pleasant Valley Conservancy, seems to be especially preferred by monarchs. When we were doing research on this species we established a milkweed forbs garden where all the species in the table except short green milkweed were planted. The monarchs went preferentially to the purples, ignoring the other species that were growing nearby. In order to protect our purple milkweed patches, Kathie monitored them and moved all developing monarch caterpillars to a nearby patch of common milkweed.

Milkweed species at Pleasant Valley Conservancy
Latin name
Common name
Asclepias exaltata
Poke milkweed
Woodlands and savannas
Asclepias incarnata
Swamp milkweed
Wetlands and wet prairies
Asclepias purpurascens
Purple milkweed
Asclepias syriaca
Common milkweed
Savannas and prairies
Asclepias tuberosa
Butterfly milkweed
Dry mesic prairies
Asclepias verticillata
Whorled milkweed
Dry mesic prairies
Asclepias viridiflora
Short green milkweed
Dry mesic prairies


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