30 ALISMACEAE. 



Family 14. ALISMACEAE. Water Plantain Family. 



Aquatic or marsh herbs with fibrous roots, scape-Hke stems 

 and basal long-petioled leaves; inflorescence a raceme or panicle; 

 flowers regular, perfect, monoecious or dioecious; pedicels whorled 

 and subtended by bracts; sepals 3, persistent; petals 3, deciduous; 

 stamens 6 or more; ovaries numerous or rarely few, 1-celled, 

 usually 1-ovuled; carpels becoming akenes in fruit; endosperm 

 none. 



Carpels in a ring upon a small flat receptacle; leaves 



ovate (in ours). 44. Alisma, 30. 



Carpels crowded in many series upon a large convex re- 

 ceptacle; leaves sagittate (in ours). 45. Sagittaria, 30. 



44. ALISMA. 



Perennial or rarely annual herbs with erect or floating leaves; 

 inflorescence a panicle or umbel-like panicle; flowers perfect, 

 small, numerous, on unequal pedicels; petals small; stamens 

 6 or 9; ovaries few or many, more or less in one whorl on a small 

 flat receptacle. 



Alisma plantago-aquatica L. Water Plantain. Scapes stout, 30-100 cm. 

 tall; leaves all radical, erect or floating, the petioles usually long, the blades 

 ovate or oblong, acute, rounded or subcordate at the base, 5-15 cm. long, 5-7- 

 nerved; flowers in a large panicle composed of 3-6 whorls of branches, these 

 again branched once or twice; flowers on pedicels 1-5 cm. long; petals white, 

 hardly exceeding the sepals; akenes obliquely obovate, compressed. 



Common in ponds and wet places. 



45. SAGITTARLV. Arrowhead. 



Perennial aquatic or marsh herbs with basal long-petioled 

 leaves; flowers monoecious or dioecious, borne near the summits 

 of the scapes in whorls of 3, the staminate usually uppermost; 

 petals usually conspicuous; stamens usually numerous; ovaries 

 numerous, crowded in globose heads. 



Sagittaria latifolia Willd. Wappato. Leaves sagittate, but varying 

 greatly in width, 10-20 cm. long, long-petioled; petals white, 1-1.5 cm. long; 

 akenes flat, each with a thin margin and bearing a stout lateral beak; rootstock 

 tuberous. 



Common in shallow water on the margins of lakes, the tubers eaten by the 

 Indians. In lakes and rivers where the European carp is introduced the 

 plant has become very rare as the fish eat the tubers. 



Family 15. HYDROCHARITACEAE. Frog's Bit Family. 



Aquatic mostly perennial herbs with opposite or whorled 

 leaves (in ours) ; flowers dioecious or polygamous, sessile or 

 peduncled, surrounded by a membranous spathe; perianth 



