MONOCOTYLEDONOUS PLANTS 21 



3. ALISMACE^. WATER-PLANTAIN FAMILY. 



Annual or perennial marsh herbs, usually with creeping run- 

 ners or rootstocks. Stems scape-like. Leaves long-petioled, 

 sheathing at the base ; petiole rounded ; blade nerved, netted, 

 or sometimes wanting. Flowers in racemes or panicles, per- 

 fect, monoecious or dioecious ; pedicels in bracted whorls. 

 Sepals 3, persistent, petals 3 or wanting. Stamens 6 or more. 

 Ovaries few or many, 1-celled, 1-seeded. Style short or none. 

 Fruit a 1-seeded akene.* 



I. ALISMA, L. 



Annual or perennial herbs. Leaves erect or floating, blades 

 prominently ribbed and netted, or even pinnately veined. 

 Scapes erect, becoming longer than the leaves, cylindrical, 

 spongy. Flowers perfect, in paniculate 3-bracted umbels, 

 small, white or pink. Stamens 6-9. Ovaries numerous in 

 one or more whorls on a flat receptacle. Fruit 1-seeded 

 akenes which are ribbed on the back and sides.* 



1. A. Plantago, L. WATER PLANTAIN. Perennial; root fibrous. 

 Leaves ovate or somewhat cordate, 5-7-nerved when erect, floating 

 leaves narrower and sometimes linear. Scapes usually single ; pan- 

 icle 1-2 ft. long ; flowering branches whorled, subtended by three 

 narrow, striate bracts ; pedicels slender, elongated. Ovaries 1520 

 in a single whorl ; base of the short style persistent, forming a beak 

 at the inner angle of the akene. Akenes obliquely obovate, 2-3- 

 keeled on the back. Common in ponds and muddy places.* 



II. SAGITTARIA. 



Perennial ; rootstocks mostly knobby or tuber-bearing. 

 Scapes erect or decumbent. Leaves long-petioled, sheathing 

 at the base, the blade round and netted, or wanting. Flowers 

 monoecious or dioecious, racemed in 3-bracted whorls of threes, 

 the upper flowers usually staminate. Sepals 3, persistent. 

 Petals 3, withering-persistent or deciduous. Stamens few or 

 many. Ovaries in globose heads, 1-ovuled ; style short, per- 

 sistent. Fruit a subglobose head of flattened akenes.* 



