Flower profile
Mat rock spiraea
Petrophytum caespitosum
Mat rock spiraea is a flowering plant that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 2 states, and across the U.S. it's most often seen in bloom in July–October.
*iNaturalist research-grade observations, as of October 17, 2026.
Quick look
Petrophytum caespitosum is a woody perennial species of flowering plant in the rose family known by the common name mat rock spiraea and native to western United States.
- It belongs to the Rosaceae family. iNaturalist
- USDA PLANTS describes it as a subshrub with a perennial life cycle. USDA PLANTS
- USDA PLANTS lists it as native in the lower 48 states and records it in 12 states. USDA PLANTS
- NatureServe lists it as native to Utah and Nevada. NatureServe
- In Utah, most iNaturalist sightings of it in flower come in August–October. iNaturalist
- In Nevada, most iNaturalist sightings of it in flower come in July–October. iNaturalist
- iNaturalist has 1,428 research-grade sightings of it in Utah, ranking #29 among the 109 flowers on our Utah list. iNaturalist
- iNaturalist has 788 research-grade sightings of it in Nevada, ranking #45 among the 110 flowers on our Nevada list. iNaturalist
Mat rock spiraea gift ideas
Handmade mat rock spiraea gifts from independent makers.
🌱 Sample spot. Handmade gift picks from independent shops will appear here once our shop partnership is approved. These cards are placeholders, not real products.
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Mat rock spiraea art print
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Mat rock spiraea greeting card
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Mat rock spiraea mug
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Mat rock spiraea earrings
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Mat rock spiraea embroidery pattern
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Mat rock spiraea sticker
When does it bloom?
Conservation status
- Federal (U.S. ESA)
- Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. USFWS ECOS
- NatureServe global
- G5 Secure worldwide. NatureServe
- Utah
- No list Utah has no state law listing endangered or threatened plants, so we show NatureServe's Utah ranks instead. NatureServe: SNR, not yet ranked in Utah.
- Nevada
- Not listed Not on Nevada fully protected plants, critically endangered (NAC 527.010). NatureServe: S4, apparently secure in Nevada. NAC 527.010
- Rare elsewhere
- No other U.S. state ranks it S1, S2, SH or SX.
Checked October 17, 2026. Rankings and lists can change, so follow the links for the latest.
Can you eat it?
None of the sources we checked (NC State Extension (no page for this plant), USDA PLANTS) say whether it's edible or poisonous for people.
It isn't on the ASPCA plant list.
🌿 Never eat a wild plant unless you're certain of its ID; this isn't medical advice. Worried about a person? Call Poison Control at 1-800-222-1222. Worried about a pet? Call your vet.
Where does it grow?
USDA PLANTS records mat rock spiraea in 12 states.
recorded by USDA PLANTS on our state lists not recorded
See the full list of states
Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, South Dakota, Texas, Utah, Wyoming.
Utah counties with USDA records: Beaver, Box Elder, Cache, Daggett, Duchesne, Garfield, Grand, Iron, Juab, Kane, Millard, Piute, Salt Lake, San Juan, Summit, Tooele, Uintah, Utah, Washington, Wayne.
Nevada counties with USDA records: Elko, Lander, Lincoln, White Pine.
More Utah flowers
Sources
- USDA, NRCS. PLANTS Database, profile PECA12.
- iNaturalist, Petrophytum caespitosum: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
- Wikipedia, Petrophytum caespitosum (lead quoted under CC BY-SA 4.0).
- Utah: Utah noxious weed list (Utah Admin. Code R68-9-3).
- Nevada: Nevada fully protected plants, critically endangered (NAC 527.010).
- Nevada: Nevada noxious weeds (NAC 555.010).
- USFWS, ECOS species database (ESA listing check), October 17, 2026.
- NatureServe Explorer, Petrophytum caespitosum (global and state ranks).
- Edibility and toxicity: no source found (marked "not well documented").
- Photo: Evan M. Raskin via iNaturalist · CC BY 4.0 · resized.