Amaranthus hybridus
Smooth pigweed, green amaranth, Green Amaranth
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Family: Amaranthaceae · Type: Herb · Not Native
Amaranthus hybridus (Smooth pigweed) is a non-native California herb in the Amaranthaceae family, recognized by . Key features: thin flexible branches, green color, variable fruit dehiscence on same plant.
Smooth pigweed is a naturalized annual found in the Central Valley, Central Western, and Southwestern California bioregions in disturbed areas and agricultural fields at elevations below 300 meters. Flowering from June to November, this plant produces green to olive green flowers in panicle-like terminal clusters with thin, flexible branches. Growing with erect stems 30 to 120 centimeters tall, it has a branching habit with green stems that become hairy toward the top. Its rhombic-ovate leaves are 50 to 120 millimeters long with wedge-shaped bases and acute tips, arranged with broad blades 20 to 60 millimeters wide. The fruit is a small circumscissile capsule 1.5 to 2.2 millimeters long, containing shiny brown to black seeds.
Identification and appearance
Key characters: 16 sympatric species. Key features: thin flexible branches, green color, variable fruit dehiscence on same plant
Habitat and range
Habitat: Disturbed areas, agricultural fields
Elevation: < 300 m
Outside California: United States, southern Canada, native to eastern North America
Bloom period
Amaranthus hybridus blooms Jun-Nov.
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 hybridus native to California?
No. Amaranthus hybridus is not native to California (recorded as not native).
When does Amaranthus hybridus bloom?
Amaranthus hybridus blooms Jun-Nov.
What plant family does Amaranthus hybridus belong to?
Amaranthus hybridus is in the Amaranthaceae family, genus Amaranthus.
What habitat does Amaranthus hybridus grow in?
Amaranthus hybridus grows in Disturbed areas, agricultural fields.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · 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.