ALISMACE^J. 225 



4. Sagltta'ria* Flowers monoecious, sometimes dioecious. Stamens 

 numerous. Carpels numerous, in more or less globular heads. 

 Leaves arrow-shaped, but varying 1 greatly. Flowers mostly in 

 whorls of 3 on the scapes, the sterile ones uppermost. 



1. TKK.l.o < HIV, L. ARROW-GRASS. 



1 . T. palus'tre, L. A slender rush-like plant, 6-18 inches 

 high, found growing in bogs northward. Carpels 3, awl- 

 pointed at the base, splitting away from below upwards. 

 Spike or raceme slender, 3 or 4 inches long. 



2. T. marit'imum, L. The whole plant is stouter than 

 No. 1, and the carpels are usually 6 in number. Atl. sea- 

 coast, and saline marshes. 



2. S< III 1 < ll/r Kl A, L. SCHEUCHZERIA. 



S. palustris, L. Stem zigzag. Flowers in a loose terminal 

 raceme, with sheathing bracts. Bogs. 



3. ALIS'JIA, L. WATER-PLANTAIX. 



A. Planta'go, L., var. America' num, Gray. Leaves 

 long-petioled, mostly oblong-heart-shaped, but often nar- 

 rower, 3-9-nerved or ribbed, and with cross veinlets between 

 the ribs. Flowers small, white, in a large and loose com- 

 pound panicle. Low arid marshy places, often growing in 

 the water. 



4, S KilTTA IMA, L. ARROW-HEAD. 



* Filaments narrow, as long as the anthers. 



1. S. varia'bilis, Engelm. Very variable in size and in 

 the shape of the leaves. Scape angled. Common every- 

 where in shallow water. 



Var. obtusa, Engelm., is dioecious, and has large obtuse 

 leaves. 



Var. latifolia, Engelm. , is monoecious, with large broad 

 acute leaves. 



Var. angustifo'lia, Engelm., has narrow leaves, with 

 long and linear diverging lobes. 



* * Filaments very short, with enlarged mostly glandular base. 



2. S. heterophyl'la, Pursh. Scape weak and at length 

 procumbent. Leaves lanceolate or lance-ovate, entire, or 

 with one or two narrow basal sagittate appendages. 



