Amaranthus tuberculatus var. rudis
Common waterhemp
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Family: Amaranthaceae · Type: Perennial · Not Native
Amaranthus tuberculatus var. rudis (Common waterhemp) is a non-native California perennial in the Amaranthaceae family, recognized by . Key features: dioecious, linear spikes, reduced pistillate perianth parts (1-2 only).
Common waterhemp is a naturalized annual herb found in the Sacramento Valley and Southern California coastal areas in disturbed areas and agricultural fields at elevations below 250 meters. Flowering from July to October, this plant produces green to purple flowers in dense terminal spikes 3 to 15 centimeters long. Growing with erect or ascending stems 50 to 150 centimeters tall, it has green or purple branches that are mostly smooth. Its leaves are ovate to narrowly lanceolate, 15 to 150 millimeters long with flat margins and a narrow wedge-shaped base. The fruit is a small, wrinkled, green-brown to reddish capsule about 1.5 to 2 millimeters long that splits circumscissile to release tiny dark red-brown seeds.
Identification and appearance
Key characters: 15 sympatric species. Key features: dioecious, linear spikes, reduced pistillate perianth parts (1-2 only)
Habitat and range
Habitat: Disturbed areas, agricultural fields
Elevation: < 250 m
Outside California: United States, Canada, Europe, native to central United States
Bloom period
Amaranthus tuberculatus var. rudis blooms Jul-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 tuberculatus var. rudis native to California?
No. Amaranthus tuberculatus var. rudis is not native to California (recorded as not native).
When does Amaranthus tuberculatus var. rudis bloom?
Amaranthus tuberculatus var. rudis blooms Jul-Oct.
What plant family does Amaranthus tuberculatus var. rudis belong to?
Amaranthus tuberculatus var. rudis is in the Amaranthaceae family, genus Amaranthus.
What habitat does Amaranthus tuberculatus var. rudis grow in?
Amaranthus tuberculatus var. rudis grows in Disturbed areas, agricultural fields.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CalPhotos
Last updated 2026-09-30
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.