Alismataceae

By: Pratikshya Chalise & Ranee Prakash

Taxon Description 

Annual or perennial, emergent, aquatic herbs, sometimes tuberous or stoloniferous. Leaves all basal, submerged leaves linear-lanceolate, phyllodial leaves occasionally present, petiolate leaves aerial, floating or submerged, venation parallel or indistinct. Inflorescence umbellate, racemose or paniculate. Flowers pedicellate, actinomorphic, bisexual or unisexual. Sepals 3, free, persistent. Petals 3, free. Stamens 3, 6, or many, free. Carpels numerous, free, ovary superior. Fruit a head of achenes (Alisma, Sagittaria), sometimes follicles (Butomopsis) or drupaceous achenes (Caldesia), mostly single-seeded, sometimes many-seeded. Embryo horse-shoe shaped.

Taxon Statistics

Worldwide 17 genera and 115 species in temperate and tropical regions. Four genera and five species in Nepal.

Key to Genera

1a. Inflorescence a terminal umbel. Fruit a follicle ………………………………………………………………………………………………………….…………….…………….………….……….… 2. Butomopsis

b Inflorescence a raceme or panicle, rarely an umbel. Fruit an achene ………………………………………………………..…………….…………….……………………………………………………….…… 2

2a Male flowers in the upper part of the inflorescence, female or bisexual flowers in the lower parts ..…………………….…………….…………….…………..………..………. 4. Sagittaria

b Flowers all bisexual ……………………………………………………………..……..………..………..………..………..………..………..………………….…………….…………….………………………..………..…………… 3

3a Tuberous. Stamens 6. Carpels in a single whorl …….………………………..…..………..………..………..………..……………….…………….…………….…………..…..………..………..………… 1. Alisma

b Rhizomatous. Stamens 9 to many. Carpels spirally arranged ……….…..………..………..………..……………….…………….…………….…………….…..………..………..………….……… 3. Caldesia