

Prickly Russian Thistle Salsola tragus
Prickly Russian Thistle is an introduced annual herb, found in Canada, Hawaii, and the lower 48 states. It blooms May – Nov.
Prickly Russian Thistle is flagged invasive in the U.S. These natives fill a similar niche — same growth habit, bloom season, height, and region — so you keep the look and feed local wildlife instead of spreading a problem.
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 4 derived from its U.S. range
- Lifespan
- Annual
- Foliage
- Broadleaf
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~11 caterpillar species
Salsola supports ~11 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 for introduced plants — native genera typically support far more.
Recorded feeding on Salsola in North America, including:
✦ Bees 59 bee visitors
59 native & managed bee species are documented visiting Prickly Russian Thistle — the 12 most-recorded:
Wildlife & visitors 1 bird · 1 mammal · 5 nectaring
Open records of who else uses Prickly Russian Thistle — a generalist food-web signal, kept separate from the keystone Ecological Value.
Recorded eaten by 1 bird and 1 mammal species (fruit, seed, browse):
5 adult butterfly & moth species are recorded nectaring at its flowers:
How we know this (2) Methods & honest limits
A recorded categorical fact: each species is tagged C3 (standard), C4 (heat/water-efficient) or CAM (succulent, night-time CO₂ uptake) — or a facultative combination. We only show a trait card for the noteworthy C4/CAM cases; C3 is the unremarkable majority, kept in the data but not surfaced as a card.
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 (21) 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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