Beetle Spurge Euphorbia eriantha
Beetle Spurge is an annual wildflower native to the lower 48 states. It blooms Feb – Oct. A host for pollen-specialist native bees.
More about this plant
Euphorbia eriantha is a species of spurge known by the common name beetle spurge. It is also called the Desert Poinsettia and Mexican Poinsettia. It is native to the deserts of northern Mexico and the southwestern United States from California to Texas. Its flowering season is from February to October in Arizona; March to April in California; January to December in Texas. This is an annual herb reaching anywhere from 15 to 50 centimeters in height. The leaves are long, narrow, and pointed, sometimes with sparse hairs, and 2 to 7 centimeters long. The foliage may be dark in color, from greenish to purplish or reddish. The inflorescence appears at the tip of the branch and contains staminate or pistillate flowers which are just a few millimeters wide. The fruit is an oblong, hairy capsule half a centimeter long, with gray and black mottling. It contains bumpy white or gray seeds. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 8 derived from its U.S. range
- Lifespan
- Annual
- 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 →❧ Caterpillar hosts ~7 caterpillar species
Euphorbia supports ~7 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 modest genus.
Recorded feeding on Euphorbia in North America, including:
+ 8 more species → ↑ show fewer
✦ Bees specialist-bee host
Specialist native bees depend on it.
Some native bees are pollen specialists (oligolectic) — they raise young only on pollen from particular plant genera. Euphorbia is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.
Related plants
More Euphorbia →
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 (16) 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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