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 all 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. PI. 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. (-1. brcrijws 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. ;ind 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. 



I'..-is;iI-lobes acute . . . . . . . . . . 1. S. arifolia. 



B;isal-lobes obtuse 2. S. hebetiloba. 



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



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



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

 pi. 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 roundfed summit of the body. Type locality, 

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

 ing. 



