White-stemmed Milkweed
Asclepias albicans
White-stemmed Milkweed, Asclepias albicans, observed in the Muggins Mountain Wilderness, Yuma, County, Arizona, USA on 31 January 2010.
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SUCCULENT: Similar to
Desert Milkweed (Asclepias subulata) but with smooth wand-like
stems much taller and thicker in diameter. Leafless stems are blue-green in
color and rise sometimes well past 2 meters.
The lower portions of the stems are woody.
RANGE: Generally restricted to far southwestern Arizona where hard
freezing temperatures are rare. Western Maricopa and Yuma Counties. Also found
in Southern California, Sonora and Baja California, Mexico.
LEAVES: A few linear leaves may be seen at growing tip of stems, but are
soon deciduous leaving the plant essentially leafless.
STEMS: When injured the stems exude copious milky latex. The cortex of
the stems conducts required photosynthesis.
FRUIT: Pods with wrinkled-looking valves. The seeds are comose for wind
dispersal. Dried pod valves hang onto the stems for many months after the
seeds have dispersed.
FLOWERS: Five-poined, star-shaped, green or white, borne in umbels of 8
to 15 flowers at the terminus of the stems. The flowers are slightly smaller
than those of Asclepias subulata
UNARMED.