16 Alismaceae 



Family 5. AL.ISMACEAE. WATER-PLANTAIN FAMILY. 



Aquatic or marsh plants, with scapose stems and radi- 

 cal long petioled sheathing leaves. Inflorescence race- 

 mose or paniculate. Flowers regular perfect, monoecious 

 or dioecious, pedicelled ; the pedicels in whorls and sub- 

 tended by bracts. Perianth segments 6, the outer 3 

 small herbaceous persistent ; the inner 3 larger and peta- 

 loid, deciduous. Stamens 6 or more ; anthers 2-celled, 

 extrorse or dehiscing by lateral slits. Ovaries numerous 

 distinct on a flat or convex receptacle, 1-celled, 1-ovuled. 

 Carpels becoming achenes in fruit. 



Flowers perfect. 1. ECHINODORUS. 



Flowers polygamous. 2. LOPHOTOCARPUS. 



Flowers monoecious or dioecious. 3. SAGITTARIA. 



1. ECHINODOR-US Rich. BUR-HEAD. 



Perennial or annual herbs with long-petioled, elliptic 

 ovate or lanceolate, often cordate or sagittate leaves, 

 3-9-ribbed and mostly punctate with dots or lines. 

 Scapes often longer than the leaves. Inflorescence race- 

 mose or paniculate. Flowers perfect, in whorls, each 

 whorl with 3 outer bracts and numerous inner bracteoles. 

 Petals white. Receptacle large convex or globose. Sta- 

 mens 12-30. Ovaries numerous ; style obliquely apical, 

 persistent ; stigmas simple. Achenes more or less com- 

 pressed, ribbed and beaked, forming spinose heads. 



1. E. cordifolius (L.) Griseb. Leaves variable, usually broadly 

 ovate, obtuse, cordate at the base, 12-16 cm. long and wide, some- 

 times lanceolate and smaller; petioles angular, striate, 5-15 cm. 

 long; scapes 1 or more, erect 10-30 cm. high; flowers 3-6 in each 

 whorl, on pedicels 6-12 mm. long; bracts linear-lanceolate, acu- 

 minate dilated at the base ; inner perianth segments shorter than 

 the outer, 4-6 mm. long; stamens usually 12; styles exceeding 

 the ovaries in length; fruiting heads bur-like, 4-6 mm. in diam- 



