Alismaceae 35 
or united at the base, |-celled, 1—3-ovuled. Carpels divergent, inflated, coriaceous, 
|—2-seeded, follicle-like. (Honor of J. and J. J. Scheuchzer, Swiss botanists.) W. 
ap Oe S. palustris L. 
ALISMACEAE Water-plantain Family 
Aquatic or marsh herbs, annual or perennial, acaulescent. Leaves basal; petiole 
elongate, sheathing at base; blades flat, several-ribbed, often with spreading or deflexed 
lobes. Scapes erect or floating, with simple or branched inflorescence. Flowers perfect 
or unisexual, regular, whorled, borne in terminal racemes or panicles. Calyx of 3 per- 
sistent green sepals. Corolla white or pink, of 5 deciduous imbricate petals. Stamens 6 
or more. Carpels few——many, distinct, whorled capitate. Fruit a@ head or whorl of flat 
or turgid akenes. 
A. Leaves not sagittate, altho sometimes cordate at base; flowers in compound panicles, 
perfect; akenes in a whorl; receptacle depressed. ALISMA (p. 35) 
AA. Leaves sagittate; flowers in whorls or 3 near the top of the scape, monoicous 
or dioicous; akenes in a head; receptacle convex to globose. SAGITTARIA (p. 35) 
ALISMA WATER-PLANTAIN 
Annual or perennial, scapose. Leaves erect or floating; leaf-blades several-veined, 
without basal lobes but sometimes cordate, gradually or abruptly narrowed into petiole. 
Sepals wide, usually ribbed. Petals white or pinkish, spreading. Stamens 6, 2 opposite 
each petal. Carpels few—-many. Akenes in | depressed discoid whorl, ribbed or grooved 
on the back. Ours in marshes and along ponds and lakes. (Celtic alis—water; referring 
to habitat.) 
A. Petals white, 5—6 mm. long; peduncles and pedicels straight, ascending; akenes 
obovate, 3—5 mm. long, grooved on the back, the inner edges not meeting within 
the whorl. W.C. E. (A. brevipes.) 
A. plantago-aquatica L. 
AA. Petals pink, 2—4 mm. long; peduncles and pedicels recurved; akenes suborbicular, 
about 2 mm. in diameter, ridged on the back, the inner edges meeting within the whorl. 
Ee A. geyeri T. & H. 
SAGITTARIA ARROW-HEAD 
Perennial, either more or less emersed and erect, or else submerged and floating; 
rhizome irregularly thickened or tuber-bearing. Leaves various, of petiole and blade 
or much reduced, those not submerged strikingly arrow-head-like (in ours). Scapes 
sometimes greatly elongated, usually simple at least below the inflorescence. The lower 
whorl of flowers usually pistillate, the upper usually staminate. Staminate flowers with 
several—many stamens. Pistillate flowers with many distinct carpels. Akenes numer- 
ous, flat, beaked, densely crowded in globular heads. Ours in ponds and at lake-mar- 
gins. (L. sagitta—arrow; referring to leaf-form.) 
A. Bracts of the inflorescence ovate-lanceolate or narrower, acuminate; fruit-heads 
1—1.5 cm. in diameter; beak of akene erect, less than '% its length. C. E. (S. 
arifolia stricta; S. cuneata.) §, arifolia Sm. (Floating Arrow-head) 
AA.  Bracts of the inflorescence ovate, acute or obtuse; fruit-head 1.5—-3 cm. in diam- 
eter; beak of akene horizontal or oblique, more than 14 its length. W. C. E. 
S. latifolia Willd. (Wapato) 
