HYDROCHAEIDE^E. 801 



LXXIX. THE HYDROCHARIS FAMILY. HYDRO- 

 CHARIDE.E. 



Aquatic herbs, with undivided leaves, and mostly dioecious 

 flowers, enclosed when young in an involucre or spatha of 1 to 3 

 leaves or bracts. Perianth of 3 or 6 segments, either all petal- 

 like or the 3 outer ones smaller and herbaceous, w4th a tube 

 adherent to the ovary at its base in the females, without any 

 tube in the males. Stamens in the males 3 to 12. Ovary in the 

 females inferior, 1-celled, with 3 parietal placentas, or divided 

 into 3, 6, or 9 cells. Styles 3, 6, or 9, with entire or 2-cleft 

 stigmas. Fruit small, ripening under water, indehiscent. Seeds 

 several, without albumen. 



A small Order, widely diffused over the globe. 



Stem floating and branched, with small opposite or whorled 

 leaves. Female perianth-tube long and thread-like. 

 Stigmas 3 1. Elodea. 



Stem root-like, with floating tufts of orbicular leaves. Fe- 

 male perianth-tube short, on a slender pedicel. Stig- 

 mas 6 2. Feogbit. 



Stem scarcely any. Leaves tufted, succulent, radical. Fe- 

 male perianth-tube short, on a stout pedicel. Stigmas 6 3. Stratiotes. 



I. ELODEA. ELODEA. 



Stems submerged, branched, and leafy. Flowers sessile, the males 

 with 9 stamens, the females with a long, thread-like perianth-tube. 

 Style adherent to the tube, with 3 notched or lobed stigmas. Ovary 

 1-celled, with 3 parietal placentas. 



A small genus, exclusively American. 



1. Canadian Elodea. Elodea canadensis, Rich. (Fig. 965.) 



(Anacharis Alsinastrum, Bab. Man.) 



A dark green, much branched perennial, entirely floating under 

 water. Leaves numerous, opposite or in whorls of 3 or 4, sessile, linear- 

 oblong, transparent, 3 or 4 lines long. Female flowers, the only ones 

 known in this country, sessile in the upper axils, in a small, 2-lobed 

 spatha ; the slender perianth-tube often 2 or 3 inches long, so as to 

 attain the surface of the water, where it terminates in 3 or 6 small, 

 spreading segments. Male flowers unknown as yet in this country, 

 and seldom observed anywhere. 



VOL. II. 2 A 



