Amaranthus spinosus
Spiny amaranth, thorny amaranth, Thorny Amaranth
(c) Tony Rebelo, some rights reserved (CC BY-SA), uploaded by Tony Rebelo · licence
Family: Amaranthaceae · Type: Herb · Not Native
Amaranthus spinosus (Spiny amaranth) is a non-native California herb in the Amaranthaceae family, recognized by . Key features: paired spines at nodes - unique among amaranths.
Spiny amaranth is a naturalized annual herb found in southern California and western Mojave Desert regions on roadsides and disturbed areas at elevations below 700 meters. Flowering from June to October, this plant produces small green flowers in dense axillary and terminal clusters with a silver-green appearance. Growing with erect stems 20 to 100 centimeters tall, the plant features distinctive paired spines at each node that diverge 8 to 15 millimeters from the stem. Its leaves are broadly ovate, 10 to 15 centimeters long with wedge-shaped bases and slightly wavy margins. The fruit is small, nearly spherical, and produces dark brown to black smooth, shiny seeds about 1 millimeter in diameter.
Identification and appearance
Key characters: 16 sympatric species. Key features: paired spines at nodes - unique among amaranths
Habitat and range
Habitat: +- rare waif roadsides, disturbed areas
Elevation: < 700 m
Outside California: to eastern United States, +- cosmopolitan, native to tropical America
Bloom period
Amaranthus spinosus blooms Jun-Oct.
How to tell it apart
vs Celosia: Amaranthus has bristly flower spikes; Celosia has showy velvety flower plumes or crested combs.; vs Rumex: Amaranthus has dense bristly flower clusters; Rumex has flowers in whorls along stems with papery wings on fruits.; vs Salsola: Amaranthus has soft oval leaves and clustered flowers; Salsola has spine-tipped leaves and papery winged fruits.; vs Euphorbia: Amaranthus lacks milky sap and has separate male/female flowers; Euphorbia has milky sap and cup-like flower clusters.; vs Chenopodium: Amaranthus has bristly flower clusters; Chenopodium has mealy-coated leaves and flowers in loose balls.
Frequently asked questions
Is Amaranthus spinosus native to California?
No. Amaranthus spinosus is not native to California (recorded as not native).
When does Amaranthus spinosus bloom?
Amaranthus spinosus blooms Jun-Oct.
What plant family does Amaranthus spinosus belong to?
Amaranthus spinosus is in the Amaranthaceae family, genus Amaranthus.
What habitat does Amaranthus spinosus grow in?
Amaranthus spinosus grows in +- rare waif roadsides, disturbed areas.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
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.