16 ALISMACEAE. 



Family 8. ALISMACEAE. 



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. 



Carpels in 1 series; achenes verticillate. 1. Alisma. 



Carpels in several series; achenes capitate. 



Flowers perfect. 2. Echinodorus. 



Flowers polygamous or unisexual. 



Lower flowers perfect, upper staminate. 3. Lophotocarpus. 

 Lower flowers pistillate, the upper usu- 

 ally staminate. 4. Sagittaria. 



1. ALISMA L. Water- PLANTAIN. 



Perennial or rarely annual herbs, with erect or floating 

 basal leaves, several-ribbed, these connected by trans- 

 verse veinlets. Flowers numerous, in pyramidal pani- 

 cles, on unequal 3-bracteolate pedicels. Petals white or 

 rose tinged. Stamens 6-9 ; ovaries few to many, arranged 

 in one whorl on a flat receptacle. Achenes 2-3-ribbed, 

 curved on the back and 1-2-ribbed on the sides. 



1. A. plantago L. Rootstock becoming bulbous by the sheath- 

 ing bases of the petioles; leaves basal, elliptic-oblong, acute, 5-15 

 cm, long, tapering from the middle to each end, on petioles twice as 

 long; scapes 4-8 dm. high, the whorled branches forming a loose 

 pyramidal panicle; petals 2 mm. long, white; achenes strongly flat- 

 tened, oblong, 2 mm. long, 15-25 in a whorl. 



A widely distributed species ranging over both hemispheres. 

 Not common in southern California, and known within our limits 

 only at Cienega (Moxley). 



2. ECHINODORUS Rich. Bur-head. 



Perennial or annual herbs with long-petioled, elliptic 

 ovate or lanceolate, often cordate or sagittate leaves, 



