Annual herb from spreading roots; stems erect to decumbent, solitary, simple or branched at the bases, 5-40 cm tall.
Basal leaves lacking; stem leaves usually opposite, unstalked, oblong-lanceolate, 2-4 cm long, 2-8 mm wide, heart-shaped and clasping at the base, glabrous.
Inflorescence of 2-5, rarely 1, urn-shaped flowers in compact axillary clusters; petals usually 4, purplish, 3-4 mm long; styles at least 1 mm long, slightly exserted from the 4-toothed calyx.
Capsules, membranous, nearly round, about 4 mm long.
If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.
Illustration Source: The Illustrated Flora of British Columbia
Synonyms and Alternate Names:
Ammannia coccinea Rottb.
Ammannia coccinea subsp. robusta (Heer & Regel) Koehne
Ludwigia scabriuscula Kellogg
Ammannia robusta shares habitat with Rotala ramosior and may be separated from it by its lavender to scarlet flowers (Washington Natural Heritage Program website, accessed March, 2005). Additionally, leaves of A. robusta are sessile and clasping at the base whereas leaves of R. ramosior gradually taper to a distinct petiole (Douglas 1995). Ammannia robusta has at least some leaf axils with three to five flowers, while R. ramosior rarely has more than one flower per leaf axil (Douglas 1995).
Source: British Columbia Conservation Data Centre