98 



ALISMACEAE 



Carpels borne in one series; achenes verticillate. 



Style lateral; achenes minutely beaked; anthers short; iietals entire. 

 Style apical; achenes long-beaked; anthers elongate; petals incised. 

 Carpels borne in several series; achenes capitate. 

 Flowers perfect. 

 Flowers polygamous or unisexual. 



Lower flowers perfect, upper staminate. 



Lower flowers pistillate, the ujiper usually staminate. 



1. Alisma. 



2. Machaerocaypus. 



3. Echinodonis. 



4. Lopltotocarpiis. 



5. Sagittaria. 



1. ALISMA L. Sp. PI. 342. 1753. 



Perennial or rarely annual herbs, with erect or floating basal leaves, several-ribbed, 

 these connected by transverse veinlets. Flowers numerous, in pyramidal panicles, 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. (Greek, the old classical name.) 



Type species, Alisma plantago-aquatica L. A genus of about 6 or 8 species, widely distributed in tem- 

 perate and tropical regions. 



Achenes longer than wide, grooved on the back, the inner edges not meeting in the whorl; pedicels very 

 slender, ascending. L A. plantago-aquatica. 



Achenes as wide as long, ridged on the back, the inner edges meeting in the whorl; pedicels stout, widely 

 divergent in fruit. 2. A. geyeri. 



1. Alisma plantago-aquatica L. 



Common Water-plantain. Fig. 206. 



Alisma plantago-aquatica L. Sp. PI. 342. 1753. 

 Alisma subcordatum Raf. Med. Rep. 6: 362. 1808. 

 Alisma brevipes Greene, Pittonia 4: 158. 1900. 



Plants erect, glabrous, the rootstocks becoming bulbous 

 by the sheathing bases of the petioles. Leaves all basal, 

 oblong to ovate or sometimes narrower, 3-15 cm. long, 

 usually abruptly pointed at the apex, cuneate to cordate at 

 the base ; the petioles often longer than the blades ; scapes 

 1-10 dm. tall, solitary or several together, the branches 

 and pedicels in whorls of 3-10, variable in length, usually 

 very slender to almost filiform ; bracts lanceolate or linear, 

 often acuminate ; sepals broadly ovate to suborbicular, ob- 

 tuse ; petals white or pinkish 1-2 mm. long; fruiting heads 

 3.5-4.5 mm. broad; achenes obliquely obovate, 1.5-2 mm. 

 long, the beak ascending. 



Growing in shallow water or in wet ground and widely distributed 

 over the northern hemisphere. Type locality: Europe. 



2. Alisma geyeri Torr. 

 Geyer's Water-plantain. Fig. 207. 



Alisma gcvcri Torr. in Nicollet, Rep. Hydrograph. 

 Miss. Riv. 162. 1843. 



Plants diffuse, glabrous. Leaves oblong, 

 elliptic, oblong-lanceolate or ovate-lanceo- 

 late, or rarely linear, 5-9 cm. long, acute or 

 slightly acuminate at the ape;c, narrowed at 

 the base ; petioles usually longer than the 

 blades ; scapes mostly 1-5 dm. long, more 

 or less diffusely spreading, the branches and 

 pedicels relatively stout, the latter widely 

 divergent in fruit; bracts lanceolate; 

 sepals orbicular-ovate, about 2.5 mm. long; 

 petals pink, 2-4 mm. long; fruiting heads 

 4.5-5.5 mm. broad ; achenes suborbicular, 

 about 2 mm. in diameter, ridged on the 

 back, the beak erect or nearly so. 



In shallow water or wet ground, mainly Ca- 

 nadian Zone; western New York to North Dakota, 

 Nevada, Oregon, and Washington. In the Pacific 

 States it has been collected near Dalles City, Ore- 

 gon, and in Klickitat County, Washington. Type 

 locality: near Devil's Lake, North Dakota. 



