ALISMATACEAE

WATER-PLANTAIN FAMILY

Charles E. Turner

Annual, perennial herb from corms, stolons, rhizomes, or tubers, aquatic (± emergent or on mud), generally bisexual; roots fibrous
Stem: caudex short
Leaves: basal, simple, palmately veined, sometimes floating; submersed blades generally linear to ovate; emergent blades linear to sagittate
Inflorescence generally scapose, umbel- to panicle-like; flowers whorled, in interrupted clusters
Flowers bisexual or unisexual, radial; sepals 3, generally green, generally persistent; petals 3, generally > sepals, white or pink; stamens 6–many; pistils 6–many, generally simple
Fruit: achene, generally compressed, beaked
Genera in family: ± 12 genera, 75–100 species: especially n hemisphere
Reference: [Rogers 1983 J Arnold Arbor 64: 383–420]

ALISMA

WATER PLANTAIN

Perennial; caudex generally corm-like
Leaf: blade linear to ovate, tapered to base or petioled
Inflorescence: peduncle generally smooth; pedicels < 45 mm in fruit
Flower bisexual; receptacle generally flat; sepals generally 1–4 mm; petals ± entire to slightly cut, white or pink; stamens generally 6; pistils many, free, in 1 whorl
Fruit: body generally 1.5–3 mm, erect, generally strongly compressed, lateral walls opaque to translucent, back thin-ridged; beak < body, generally lateral
Species in genus: ± 9 species: generally n temp
Etymology: (Greek: ancient name)
Reference: [Bjorkqvist 1968 Opera Bot 19:1–138]
North America species need careful study.

Introduced

A. lanceolatum With.

Leaf 12–40 cm; blade 6–12 cm, 1–3 cm wide, generally lanceolate, base tapered
Inflorescence generally >> leaves; pedicels generally ascending to erect
Flower: petals pink; style ± straight, erect
Fruit: lateral walls generally thin, translucent
Chromosomes: 2n=26,28
Ecology: Ponds, rice fields, ditches, slow streams
Elevation: < 500 m.
Bioregional distribution: Northwestern California, n Sierra Nevada Foothills, Sacramento Valley
Distribution outside California: Oregon, also Chile, Australia; native to Eurasia, n Africa