Whitestem Milkweed Asclepias albicans
Whitestem Milkweed is a perennial shrub native to the lower 48 states. It grows to 2.6 ft and blooms Mar – Apr. Monarch host plant.
More about this plant
Asclepias albicans is a species of milkweed known by the common names whitestem milkweed and wax milkweed. It is native to the Mojave and Sonoran Deserts of California, Arizona, and Baja California. This is a spindly erect shrub usually growing 1 to 3 meters tall, but known to approach 4 metres. The sticklike branches are mostly naked, the younger ones coated in a waxy residue and a thin layer of woolly hairs. The leaves are ephemeral, growing in whorls of three on the lower branches and falling off after a short time. They are linear in shape and up to 3 centimeters long. The inflorescence is an umbel about 5 cm (2 in) wide which appears at the tips of the long branches and sprouting from the sides at nodes. The inflorescence contains many purple-tinted greenish flowers, each about 1.5 cm wide, with a central array of bulbous hoods, and corollas reflexed back against the stalk. In its native range it is an evergreen perennial. The plant usually blooms all year long. The fruit is a large, long, thick follicle which dangles from the branch nodes. It grows in dry, rocky places in the desert. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 10 derived from its U.S. range
- Height
- 2.6 ft
- Lifespan
- Perennial
- Foliage
- Broadleaf
- Flower colour
- Green AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
Wildlife & pollinators
How pollinator value is scored →★ Monarch Larval host plant
A monarch host plant.
Monarch caterpillars eat only milkweeds (Asclepias). As a native milkweed, Whitestem Milkweed is a documented larval host across its breeding range.
❧ Caterpillar hosts ~12 caterpillar species
Asclepias supports ~12 caterpillar species.
Native butterfly & moth caterpillars are the base of the terrestrial food web — most songbirds rear their young almost entirely on them. As a host for native Lepidoptera this is a moderate genus.
Recorded feeding on Asclepias in North America, including:
+ 8 more species → ↑ show fewer
Wildlife & visitors 2 nectaring
Open records of who else uses Whitestem Milkweed — a generalist food-web signal, kept separate from the keystone Ecological Value.
2 adult butterfly & moth species are recorded nectaring at its flowers:
Related plants
More Asclepias →
How we know this (2) Methods & honest limits
We take the plant’s U.S. county range and look up each county’s long-term climate, then summarise: native rainfall = the median annual rainfall across its counties; heat tolerance = the warm end (90th percentile) of average temperature across its range (mirroring how our cold-hardiness floor uses an extreme). Counties + medians blunt the roadside/observer bias that makes point-level climate unreliable. Needs at least five placeable counties.
Honest limits: A realized, sampling-biased niche (where it has been recorded, not its physiological optimum), and county climate is coarse — large Western counties span deserts and mountains. Derived guide, never a measured fact.
McKenzie et al. assigned each species a flower colour with a GPT-4V vision model over iNaturalist photos. We use the confident tier plus a separately-labelled lower-confidence top-up (mostly inconspicuous green/brown flowers), and render it as a small tint — never as an asserted fact, and kept out of the written synopsis.
Honest limits: AI image inference (~87% expert agreement on the confident tier); a decorative, confidence-tiered indicator, not a measured trait.
Sources for this entry (22) Open & cited
Cite this page Open data, please attribute
PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).
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