Horsetail Milkweed
Asclepias subverticillata
In open ponderosa woodland near the headwaters of the East Verde River, Gila Co., Arizona, USA. 21 Aug. 2010. A pair of red and black Milkweed Bugs (Lygeaus kalmii) can be seen as well as a small geometrid moth.
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FLOWERS: Bright white flowers are conspicuously five pointed and set in
umbels of a dozen or so flowers. A flurry of insects are often present to take
nectar.
LEAVES: The leaves are very narrow - almost grass-like. Two or three
such leaves are set at each stem node, thus another common name, Whorled
Milkweed.
PERENNIAL HERB: Typically regrowing for several years up to a height of
1 m. Stem break ooze milky latex which is poisonous. Livestock can be
poisoned by eating this plant rendering still another common name, Poison Milkweed.
RANGE: Fairly common on mostly disturbed sites in the ponderosa zones of
Arizona New Mexico and Colorado. Also among piñon-juniper.
FRUIT: Paired turgid fruits develop from each flower after pollination.
The many seeds inside have copious white hairs.
UNARMED. No spines or prickles.
Asclepiadaceae -- Milkweed Family
More Information:
- Southwest Environemtnal Information Network
- Southwest Colorado Wildflowers
- USDA Plant Profile
- ITIS Taxonomic Report
- Google Images
- Google Scholar Literature Search