Euphorbia vallis-mortae
Death valley sandmat, Death Valley Sandmat
(c) Ken-ichi Ueda, some rights reserved (CC BY) · licence
Family: Euphorbiaceae · Type: Herb · Native
Conservation status: CNPS 4.2
Euphorbia vallis-mortae (Death valley sandmat) is a native California herb in the Euphorbiaceae family, recognized by densely hairy when young, larger involucres.
Death valley sandmat is a California native perennial ranked 4.2 by CNPS, found in the eastern Sierra Nevada and Mojave Desert regions in dry, sandy places at elevations below 1,300 meters. Flowering from May to October, this plant produces white petal-like appendages surrounding small green to yellow or reddish glands in distinctive cyathia at branch tips. Growing with prostrate to decumbent stems that repeatedly fork and spread in a two-faced pattern, it forms dense low-growing clusters up to several centimeters wide. Its opposite leaves are small, 4 to 6 millimeters long, with oblong to ovate blades that have asymmetric bases and obtuse tips. The fruit is a small 2-millimeter ovoid structure with subtle lobes, producing smooth white seeds less than 2 millimeters long.
Identification and appearance
Key characters: 14 sympatric species; densely hairy when young, larger involucres
Habitat and range
Habitat: Dry, sandy places
Elevation: < 1300 m
California counties: Kern, Inyo
Bloom period
Euphorbia vallis-mortae blooms May-Oct.
Conservation status
CNPS 4.2
How to tell it apart
vs Croton: Euphorbia bleeds milky white latex and packs its flowers into a tiny cup (cyathium) rimmed with nectar glands; Croton has watery sap, stellate or scaly hairs, and ordinary small separate male and female flowers.; vs Stillingia: Euphorbia flowers sit in a gland-bearing cyathium; Stillingia bears its flowers in a spike with a pair of glands flanking each subtending bract and has no cyathium cup.; vs Ditaxis: Euphorbia has latex and the cyathium; Ditaxis has clear sap, 5-parted petaled male and female flowers, and 2-forked (malpighiaceous) hairs.; vs Asclepias: Both ooze milky sap, but Euphorbia's minute flowers cluster in a cyathium and ripen into a 3-lobed capsule; milkweeds have showy 5-parted flowers with a crown and paired follicles of plumed seeds.; vs Polygonum: Prostrate mat spurges leak milky sap when torn and have paired stipules with opposite leaves at the nodes; knotweeds have clear sap and a papery sheath (ocrea) wrapping each node.
Frequently asked questions
Is Euphorbia vallis-mortae native to California?
Yes. Euphorbia vallis-mortae is native to California (recorded as native).
When does Euphorbia vallis-mortae bloom?
Euphorbia vallis-mortae blooms May-Oct.
Where in California does Euphorbia vallis-mortae grow?
Euphorbia vallis-mortae occurs in Kern, Inyo, at elevations of < 1300 m.
What plant family does Euphorbia vallis-mortae belong to?
Euphorbia vallis-mortae is in the Euphorbiaceae family, genus Euphorbia.
Is Euphorbia vallis-mortae rare or endangered?
Euphorbia vallis-mortae carries California Rare Plant Rank 4.2, state rank S3.
Related species
Other California species in the same genus, family, or bioregion.
- Euphorbia virgata — Leafy spurge
- Euphorbia abramsiana — Abrams' spurge
- Euphorbia albomarginata — Rattlesnake sandmat
- Euphorbia arizonica — Arizona spurge
- Euphorbia crenulata — Chinese caps
- Euphorbia cyathophora — Painted leaf
- Euphorbiaceae sp. — Spurge family
- Mercurialis annua — Annual mercury
- Mercurialis sp. — Mercury
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.