260 



ALISMACE^E. 



Sagittaria. 



the lobes), and 2-6 inches wide ; but in var. 4, much smaller : in 6th var. it is reduced to 

 an undivided blade sometimes not more than 2-3 lines wide. Scape 6 inches high ; the 

 flowers pedicellate, in whorls of 3 together. Pedicels bracteate at the base, from one-fourth 

 of an inch to an inch or more in length. Petals orbicular, large and white, very thin and 

 fugacious. Stamens very numerous. Ovaries crowded, in depressed globose heads. 



Low watery places : common. Fl. July - August. Fr. September. I am convinced that 

 all the above forms belong to one species, as they pass by insensible gradations into each other. 

 The most remarkable variety is the one which I take to be >S. rigida of Pursh. It grows in 

 pretty deep water, but does not float. The whole plant, except the small blades of the leaves 

 and the flowering part of the scape, is submerged. Nuttall seems to be the only botanist who 

 has noticed the milky juice of Sagittaria. It exudes in small quantities when the leaves or 

 tubers are wounded, and soon dries into a transparent gummy mass. 



2. Sagittaria pusilla, Nutt. Least Arrowhead. 



Leaves linear, short and obtuse, the lamina very small ; scape simple, few-flowered, 

 monoecious, mostly shorter than the leaves ; fertile flower usually solitary. — Nutt. gen. 2. 

 p. 213 ; Torr. compend. p. 356 ; Kunth, enum. 2. p. 160. S. subulata, Bart, compend. fl. 

 Phil. 2. p. 166. Alisma subulata, Linn. sp. (ed. 2.) 1. p. 487 ; Pursh, fl. 1. p. 253. 



Annual ? Leaves 1-3 inches high, and about a line wide ; the lamina consisting of a 

 flattened portion of the summit, or sometimes wanting. Scape 1-2 inches high, often only 

 3 - 4-flowered ; the fertile flower usually solitary. Fruit not seen. 



Muddy banks of the Hudson, where the water is a little brackish, as at West-Point and 

 Peekskill. Fl. July - August. I am suspicious that this plant is only a very reduced form 

 of S, sagittifolia. 



Suborder JUNCAGINACEiE. The Arrow-grass Tribe. 



Flowers regular. Perianth single, consisting of 6 sepaloid leaflets; the 3 inner 

 ones narrower. Stamens 6, opposite the leaflets of the perianth. Ovaries 

 3-6, united around a central axis, or partly distinct, 1-celled, each with 1 or 

 2 erect or ascending anatropous ovules : stigmas plumose or papillose. Carpels 

 more or less distinct, or united around an axis from which they separate at 

 maturity, 1 - 2-seeded. Seeds erect, marked with a strong longitudinal raphe. 

 Embryo straight. — Smooth marsh plants, with simple (usually scape-like) 

 stems and narrow linear leaves. Flowers in spikes or racemes, 



