Ammannia robusta
Grand ammania
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Family: Lythraceae · Type: Herb · Native
Ammannia robusta (Grand ammania) is a native California herb in the Lythraceae family.
Grand ammania is a California native annual found in the North Coast Ranges, southern Sierra Nevada Foothills, Central Valley, Central Western California, southern California Coast, southern Channel Islands, and desert regions in wet places, drying ponds, and ditch margins at elevations below 500 meters. Flowering from June to August, this plant produces pale flowers small and subtle, with petals 2 to 4 millimeters long. Growing with stems ranging 10 to 100 centimeters tall, the plant has an upright habit in marshy environments. Its leaves are relatively narrow, measuring 1.5 to 8 centimeters long and 5 to 15 millimeters wide, arranged oppositely along the stem. The flowers feature 4 to 5 pale yellow stamens nestled in an urn-shaped hypanthium, creating delicate botanical clusters in wet habitats.
Identification and appearance
Key characters: 1 sympatric species; anther color and flower number per inflorescence are key differentiators
Habitat and range
Habitat: Wet places, drying ponds, ditch margins
Elevation: < 500 m
California counties: Orange, San Diego, Imperial, Colusa, Los Angeles, Riverside, Butte, Tulare, Ventura, San Bernardino, Sutter, Sonoma, Marin, Solano, Napa, Sacramento, Glenn, Yuba, Tehama, Lake, San Joaquin, Humboldt, Merced, San Mateo, Yolo, Stanislaus, Madera, Kings, Santa Barbara, Fresno, Kern
Outside California: to Great Lakes, Louisiana, South America
Bloom period
Ammannia robusta blooms Jun-Aug.
How to tell it apart
vs Rumex: Ammannia has ear-lobed leaves and small clustered flowers; Rumex has sheathing leaf bases and papery winged fruits.; vs Epilobium: Ammannia has ear-lobed leaves and superior ovaries; Epilobium has smooth leaf bases and inferior ovaries.; vs Punica: Ammannia is a tiny wetland herb with ear-lobed leaves; Punica is a woody shrub with large leathery flowers.; vs Lythrum: Ammannia has ear-like lobes at leaf base; Lythrum has smooth leaf bases without lobes.; vs Rotala: Ammannia has ear-lobed leaf bases and dense flower clusters; Rotala has tapered leaf bases and solitary flowers.
Frequently asked questions
Is Ammannia robusta native to California?
Yes. Ammannia robusta is native to California (recorded as native).
When does Ammannia robusta bloom?
Ammannia robusta blooms Jun-Aug.
Where in California does Ammannia robusta grow?
Ammannia robusta occurs in Orange, San Diego, Imperial, Colusa, Los Angeles, Riverside, Butte, Tulare and other counties, at elevations of < 500 m.
What plant family does Ammannia robusta belong to?
Ammannia robusta is in the Lythraceae family, genus Ammannia.
What habitat does Ammannia robusta grow in?
Ammannia robusta grows in Wet places, drying ponds, ditch margins.
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.