42 CONTEIBUTIONS FROM THE NATIONAL HEEBAEIUM. 



12. ALISMACEAE. Water-plantain Family. 



Marsli lierbs with fibrous roots, scapose stems, spongy petioles, and oval or sagittate 

 leaf blades; leaves all radical; flowers perfect, monoecious, or dioecious; perianth of 

 3 herbaceous persistent sepals and as many wliite deciduous petals; stamens 6 or 

 more; ovaries niunerous, becoming 1-seeded achenes. 



KEY TO THE GENERA. 



Leaf blades ovate or oblong; all flowers perfect; carpels 



not winged; inflorescence paniculate 1. Alisma (p. 42). 



Leaf blades sagittate; all or part of the flowers unisexual; 

 carpels winged ; inflorescence raceme-like. 

 Lower flowers of the inflorescence pistillate; pedicels 



slender; leaves longer than broad 2. Sagittaria (p. 42). 



Lower flowers of the inflorescence perfect; pedicels 



stout; leaves broader than long 3. Lophotocarpus (p. 42). 



1. ALISMA L. Water-plantain. 



Perennial with long-petioled leaves, ovate or oblong, acute blades, and 1 or 2 scapes 

 terminating in a loose 2?yramidal panicle; flowers small; carpels numerous, in a 

 simple circle on a flattened receptacle. 



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

 Type locality: "Habitat in Europae aquosis & ad ripas fluviorum, lacuum." 

 Range: Nearly throughout North America; also in Europe and Asia. 

 New Mexico: Near Horace (TFboton). Wet ground. 



2. SAGITTARIA L. Arrow head. 



Stoloniferous perennial herbs with long-petioled sheathing leaves with sagittate 

 blades; stems simple, bearing a few whorls of flowers, the staminate flowers above, the 

 pistillate below; ovaries many, on a globular receptacle, becoming flat membranous 

 winged achenes. 



1. Sagittaria arifolia Nutt.; J. G. Smith, Rep. Mo. Bot. Gard. 6: 32. 1895. 



Type locality: Oregon. 



Range: British America southward through the western United States. 



New Mexico: San Juan Valley; Taos; Santa Fe; Belen; Reserve. Wet ground 

 chiefly in the Upper Sonoran Zone. 



3. LOPHOTOCARPUS Durand. 



A perennial herb similar to the preceding, but the lower flowers of the inflorescence 

 perfect instead of pistillate; leaves broadly sagittate. 



1. Lophotocarpus calycinus(Engelm.) J. G. Smith, Mem. Torrey Club 5: 25. 1894. 

 Sagittaria calycina Engelm. in Torr. U. S. & Mex. Bound. Bot. 212. 1859. 

 Sagittaria calycina maxima Engelm. loc. cit. 

 Sagittaria calycina media Engelm. loc. cit. 

 Type locality: "On the Red River, Louisiana." 

 Range: South Dakota and Delaware to Alabama and New Mexico. 

 New Mexico: Mesilla {Wooton 74). Wet ground, in the Lower Sonoran Zone. 



Order 10. POALES. 



KEY TO THE FAMILIES. 



Leaves 2-ranked ; margins of sheaths not united; stems 



mostly hollow 13, POACEAE (p. 43). 



Leaves 3-ranked; margins of sheaths united; stems solid. 14. CYPERACEAE (p. 110). 



