ALISMACEAE (WATER PLANTAIN FAMILY) 37 



14. ALISMACEAE DC. WATER PLANTAIN FAMILY 



Marsh herbs, with scape-like stems, sheathing leaves, and perfect or monoe- 

 cious flowers not on a spadix, furnished with both calyx and corolla. Sepals 

 and petals each 3, distinct. Ovaries numerous, distinct, becoming achenes in 

 fruit. Roots fibrous; leaves radical, petiolate, strongly nerved with trans- 

 verse veinlets, the earlier sometimes without blade; flowers in a loose raceme 

 or panicle. 



Leaves elliptic-ovate; flowers perfect . . . / * '. . . - " . 1. Alisma. 

 Leaves sagittate; flowers monoecious or dioecious . . ., 2. Sagittaria. 



1. ALISMA L. WATER PLANTAIN 



Roots fibrous. Leaves ajl from the root, several-ribbed, with connected 

 veinlets. Scape with whorled panicled branches. Flowers small, white or 

 pale rose-color, perfect. Petals involute in the bud. Stamens definite, mostly 

 6. Ovaries many in a simple circle on a flattened receptacle, forming flattened 

 coriaceous achenes, which are dilated and 2-3-keeled on the back. 



1. Alisma Plantago-aquatica L. Sp. PL 342. 1753. Perennial by a stout 

 proliferous corm: leaves long-petioled, ovate, oblong, or lanceolate, or even 

 linear, acute, mostly rounded or heart-shaped at base, 3-9-nerved: panicle 

 loose, compound, many-flowered, 3-5 dm. long: carpels obliquely obovate, 

 forming an obtusely triangular whorl in fruit. (A. brevipes Greene, Pitt. 

 4: 158. 1900.) In shallow water or on muddy banks; North America, Europe, 

 and Asia. 



2. SAGITTARIA L. ARROWHEAD 



Marsh or aquatic mostly perennial stoloniferous herbs, with milky juice 

 and fibrous roots; the scapes sheathed at base by the bases of the long cellular 

 petioles, of which the primary ones, and sometimes all, are flattened, nerved, 

 and destitute of any proper blade (i. e., are phyllodia); when present the 

 blade is arrow-shaped or lanceolate, nerved and with cross-veinlets as in 

 Alisma. Flowers monoecious, or often dioecious. Petals imbricated in the 

 bud. Stamens indefinite, rarely few. Ovaries many, crowded in a spherical 

 or somewhat triangular depressed head on a globular receptacle, in fruit form- 

 ing flat membranaceous-winged achenes. 



Beak of achene wanting or merely an erect tooth in the margin of its wing. 

 Basal-lobes of leaf shorter than the .blade. 



Basal-lobes acute . . . . . . . . . 1. S. arifolia. 



Basal-lobes obtuse . . . . . . . . . 2. S. hebetiloba. 



Basal-lobes of leaf much longer than the blade . . . . . 3. S. longiloba. 



Beak of achene i to J as long as the body . . . . . . 4. S. latifolia. 



1. Sagittaria arifolia (Nutt.) J. G. Smith, Ann. Rep. Mo. Bot. Card. 6: 32. 

 pL I. 1894. Glabrous or nearly so: leaves sagittate, usually broad, with 

 curved margin, rather abruptly acute ; the lobes acute or acuminate, divergent 

 but incurved, usually less than half as long as the blade: bracts lanceolate, 

 as long as the fertile pedicels or longer: petals white, 6-10 mm. long: fila- 

 ments glabrous: achene obovate, .2 mm. long, winged, with a short tooth-like 

 beak at one side of the summit. S. variabilis in part. On muddy banks or in 

 shallow ponds; frequent in our range, and extending from Michigan to Cali- 

 fornia. 



2. Sagittaria hebetiloba A. Nels. Bull. Torr. Bot. Club 26: 6. 1899. Very 

 similar to the preceding but usually larger in every way: leaves broad, with 

 curved sides and rounded abruptly acutish apex; the lobes broad and abruptly 

 rounded, very obtuse: beak of achene oblique or erect, very short, merely a 

 blunt tooth at the side of the rounded summit of the body. Type locality, 

 Platte Canon, eastern Wyoming; possibly local or a mere form of the preced- 

 ing. . 



