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Ecology and Conservation of Purple Milkweed

	Abstract

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Purple milkweed (Asclepias purpurascens) is a relatively rare member of the flora of oak savannas and open oak woodlands. It is endangered in several states and has been the subject of special conservation efforts. A number of native populations of this species arose spontaneously at Pleasant Valley Conservancy State Natural Area in south-central Wisconsin after oak savanna restoration was initiated in 1997. Ecological observations of permanently marked stands made over a ten-year period have shown that growth is highly variable from year to year, and flowering and seed set are sporadic and unpredictable. Germination studies have determined that seed viability is very high. Greenhouse-raised plants have been successfully transplanted to the field and followed for three years. Transplants have also been used in a forbs garden, where plants could be monitored more effectively. Pod formation and seed set are highly variable, both in the field and in the forbs garden, and may partly explain the rarity of this species.

Keywords: pod formation and seed set, pollination and pollinators, purple milkweed (Asclepias purpurascens), seed germination, transplant studies

	References

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Gleason, Henry A. 1968. The New Britton and Brown Illustrated Flora of the Northwestern United States and Adjacent Canada , vol. 3. New York: Hafner Publishing.

Robertson, Charles. 1886. Notes on the mode of pollination of Asclepias. Botanical Gazette 11:262–269.

Vande Water Natural Resource Services. 2003. Conservation assessment for purple milkweed (Asclepias purpurascens). Report prepared for U.S. Forest Service, Eastern Region, Threatened and Endangered Species Program.

Wilbur, H.M. 1976. Life history evolution in seven milkweeds of the genus Asclepias. Journal of Ecology 64:223–240.[CrossRef]

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Brock, T. D. Search for Related Content