

Christplant Euphorbia milii
Christplant is an introduced perennial shrub, found in the lower 48 states and Puerto Rico.
More about this plant
Euphorbia milii, the crown-of-thorns, Christ plant or Christ's thorn, is a species of flowering plant in the spurge family, Euphorbiaceae, native to Madagascar. The specifies commemorates Baron Milius, once Governor of Réunion, who introduced the species to France in 1821. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 11 derived from its U.S. range
- Lifespan
- Perennial
- Foliage
- Broadleaf
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 · 11 bee visitors
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.
11 native & managed bee species are documented visiting Christplant :
+ 5 more bees → ↑ show fewer
Wildlife & visitors 3 nectaring
Open records of who else uses Christplant — a generalist food-web signal, kept separate from the keystone Ecological Value.
3 adult butterfly & moth species are recorded nectaring at its flowers:
How we know this (2) Methods & honest limits
We read each species’ measured specific leaf area (leaf area per unit dry weight) from the Global Spectrum dataset and band it: thin & fast (high SLA), medium, or thick & tough (low SLA). The global median is about 10 mm²/mg.
Honest limits: A species-mean from pooled measurements — individual plants vary with light and site. A broad strategy signal, not a precise per-plant figure.
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.
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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