Asclepias speciosa is a milky-sapped perennial plant in the dogbane family (Apocynaceae), known commonly as the showy milkweed and is found in the western half of North America.[1][2]
Description
This flowering plant is a hairy, erect perennial growing up to 120 cm (47 in) in height.[3] The pointed, elongate, simple, entire leaves are about 10–20 cm (4–8 in) long and arranged oppositely on stalks.[3] Milky sap is released when the leaves or stems are bruised or cut.[4]
The flowers are about 2 cm (3⁄4 in) wide,[3] hirsute, pale pink to pinkish-purple, and occur in dense umbellate cymes. Their corollas are reflexed and the central flower parts, five hoods with prominent hooks, form a star shape. The fruit is a rough follicle about 5–10 cm (2–4 in) long[3] and filled with many flat oval seeds, each with silky hairs.
This species flowers from May through August.[2][3]
Many other species in the genus Asclepias are toxic,[3] particularly to livestock.[5]
Monarch Watch provides information on rearing monarchs and their host plants.[9] Efforts to restore falling monarch butterfly populations by establishing butterfly gardens and monarch migratory "waystations" require particular attention to the target species' food preferences and population cycles, as well to the conditions needed to propagate and maintain their food plants.[10]
For example, where it grows in Michigan and surrounding areas and in the western US, monarchs reproduce on A. speciosa, especially when its foliage is soft and fresh. Because monarch reproduction in those areas peaks in late summer when milkweed foliage is old and tough, A. speciosa needs to be mowed or cut back in June or July to assure that it will be regrowing rapidly when monarch reproduction reaches its peak.[11]
The seeds of some milkweeds need periods of cold treatment (cold stratification) before they will germinate.[12] To protect seeds from washing away during heavy rains and from seed–eating birds, one can cover the seeds with a light fabric or with an 13 mm (0.5 in) layer of straw mulch.[13] However, mulch acts as an insulator. Thicker layers of mulch can prevent seeds from germinating if they prevent soil temperatures from rising enough when winter ends. Further, few seedlings can push through a thick layer of mulch.[14]
Uses
Native Americans used fiber in the stems for rope, basketry, and nets.[2] Some Native Americans used the milky sap for medicinal purposes.[2]
Although care is needed to distinguish the species from highly toxic species in the genus,[3] the young leaves and seed pods of A. speciosa can be boiled and eaten.[15]
^Eby, Chelsea; Gardiner, Mark G.T.; Gries, Regine; Judd, Gary J.R.; Khaskin, Grigori; Gries, Gerhard (April 1, 2013). "Phenylacetaldehyde attracts male and female apple clearwing moths, Synanthedon myopaeformis, to inflorescences of showy milkweed, Asclepias speciosa". Entomologia Experimentalis et Applicata. 147 (1): 82–92. Bibcode:2013EEApp.147...82E. doi:10.1111/eea.12045. ISSN1570-7458. S2CID84552298.
^The Xerces Society (2016), Gardening for Butterflies: How You Can Attract and Protect Beautiful, Beneficial Insects, Timber Press.
^"Monarch Watch". monarchwatch.org. Retrieved September 27, 2015.
^National Academies of Sciences, Engineering, and Medicine (2020). Evaluating the Suitability of Roadway Corridors for Use by Monarch Butterflies. Washington, D.C.: National Academies Press. pp. 79–80. doi:10.17226/25693. ISBN9780309481328. LCCN2020935714. OCLC1229163481. S2CID218854539. National Cooperative Highway Research Program (NCHRP) Research Report 942. Archived from the original on July 29, 2020. Retrieved July 8, 2021. Could roadside mowing stimulate milkweed growth and support monarch breeding? Limited research in eastern North America has shown that spring or summer mowing can promote new growth and extend the availability of milkweed plants for monarch breeding. Mowing may stimulate growth of some milkweed species, particularly those that spread through rhizomes like common milkweed (A. syriaca) and showy milkweed (A. speciosa). Summer (June or July) mowing in Michigan resulted in more monarch eggs on regenerated stems than unmowed stems. Summer (July) mowing and burning can increase green antelopehorn milkweed (A. viridis) availability in the late summer and early fall in the Southern Great Plains, whereas in areas without mowing, the milkweed has senesced by August. In the West, showy milkweed will regrow after summer mowing and continue to support monarch breeding (Stephanie McKnight, personal observation). However, more research is needed in other areas to determine the optimal timing and frequency of mowing that promotes not only milkweed but also nectar plants. It is also unknown if the benefit of additional milkweed availability in the fall outweighs the costs of the larval mortality caused by summer mowing. The benefits are likely greater in areas that primarily have breeding monarchs in the spring and fall and where the dominant species of milkweed spread by rhizomes. Sources: Alcock et al. 2016; Baum and Mueller, 2015; Bhowick 1994; Haan and Landis 2019; Fischer et al. 2015{{cite book}}: CS1 maint: multiple names: authors list (link)
^(1) Borders, Brianna; Lee–Mäder, Eric (2014). "Milkweed Propagation and Seed Production: Stratification"(PDF). Milkweeds: A Conservation Practitioner's Guide: Plant Ecology, Seed Production Methods, and Habitat Restoration Opportunities. Portland, Oregon: The Xerces Society for Invertebrate Conservation. pp. 28–29. Archived(PDF) from the original on July 4, 2021. Retrieved July 12, 2021. (2) Landis, Thomas D.; Dumroese, R. Kasten (2015). "Propagating Native Milkweeds for Restoring Monarch Butterfly Habitat"(PDF). International Plant Propagators' Society, Combined Proceedings (2014). 64: 302. Archived(PDF) from the original on March 8, 2021. Retrieved July 11, 2021 – via United States Department of Agriculture: United States Forest Service. Many sources of milkweed seeds require stratification (cold, moist treatment) before sowing. In a review of stratification requirements for common milkweed, recommendations varied from as short as 7 days to as long as 11 months at 5°C (41°F) (Luna and Dumroese, 2013). Butterfly milkweed (A. tuberosa) germination increased from 29 to 48 to 62% as stratification duration increased from 0 to 30 to 60 days, respectively (Bir, 1986). Our informal natural stratification trial with showy (milkweed) and narrow leaf milkweed (A. fascicularis) in southern Oregon revealed that seeds began to germinate after 15 weeks in stratification (Fig. 3A). (3) Higgins, Adrian (May 27, 2015). "7 milkweed varieties and where to find them". Home & Garden. The Washington Post. Archived from the original on September 26, 2020. Retrieved October 17, 2020. Seed may be stubborn to germinate and may need a period of cold treatment..
