ALISMACE^E. ( WATER-PLANTAIN FAMILY.) 493 



produced all summer, mostly whorled in threes, with membranous bracts ; 

 the sterile above. (Name from sagitta, an arrow, from the prevalent form of 

 the leaves. ) 



Genus newly elaborated for this edition by Dr. Engelmann. 

 * Filaments narrow, as long as the linear-oblong anthers: scape simple or branched. 



1. S. laneifolia, L. Scape 2°- 5° high, with several of the lower whorls 

 fertile ; bracts ovate, acute or acuminate ; pedicels slender, the fertile scarcely 

 shorter than the sterile ones; filaments pubescent; achenia obovate-falcate, 

 pointed with an incurved beak ; leaves lanceolate or lance-oblong, rarely linear, 

 all with a tapering base, thick or coriaceous (6'- 18' long and on a long and 

 stout petiole, never sagittate), the nerves mostly arising from the very thick 

 midrib. (S. falcata, Pursh, and Ed. 2.) — Swamps, Virginia and southward to 

 the West Indies. 



2. S. variabilis, Engelm. Scape (\°- 4° high) angled, with one or more 

 of the lower whorls fertile ; bracts mostly pointed ; pedicels of the fertile flowers 

 about half the length of the sterile ones ; petals with white claws ; filaments 

 glabrous, nearly twice the length of the anthers ; achenia broadly obovate, with 

 a long and curved beak \ - £ its length ; leaves very various, almost always 

 sagittate. (S. sagittifolia Amer. auth. etc. — The European species has the 

 fertile pedicels only £ or $ the length of the sterile; claws of the petals purple- 

 tinged ; filaments not longer than the anthers ; achenia almost orbicular, very 

 broadly winged and with a short and straight beak.) — In water or wet places : 

 very common. — Excessively variable in size and foliage : the following are the 

 leading forms. — Var. obtusa (S. obtusa, Willd.) is large and dioecious; the 

 broadly sagittate leaves obtuse, 6' -12' long. — Var. latif6lia (S. latifolia, 

 Willd. ) is large, monoecious, with broad and acute sagittate leaves. — Var. 

 hastAta is the ordinary form, with narrow halberd-shaped or sagittate leaves 

 (including S. hastata, Pursh). — Var. diversif6lia, with some leaves lanceo- 

 late or ovate-lanceolate, others more or less sagittate. — Var. angustif6lia 

 has the narrow leaves with long and linear diverging lobes. — Var. gracilis 

 (S. gracilis, Pursh) is the most slender form, with nearly linear leaves and 

 lobes. — Var. pubescens (S. pubescens, Muhl.) : upper part of petiole and of 

 scape and especially the orbicular ovate obtuse bracts and sepals pubescent or 

 woolly; leaves obtuse or acute; beak of fruit (as also sometimes in some of the 

 other forms) horizontal, so that the fruit-head appears compact and smoothish, 

 while usually it has a squarrose surface, from the protruding and recurved beak, 

 New Jersey and southward. — A state with double flowers has been found in 

 Pennsylvania and Delaware. 



3. S. ealycina, Engelm. Scape weak (3' -9' high), at length mostly 

 procumbent ; usually only the lowest whorl fertile, with pedicels as long as 

 those of the sterile flowers, recurved in fruit ; bracts orbicular, obtuse or rarely 

 pointed ; calyx appressed to the fruit-head and partly covering it ; filaments slightly 

 rough, as long as the anthers; achenia obovate with a short horizontal style; 

 leaves broadly halberd-shaped, obtuse or acutish, with wide spreading lobes, 

 often wider than long, or lanceolate or sometimes reduced to linear phyllodia. 

 — Maine to Delaware, Wisconsin, and southward. — Var. spongiosa, with a 

 loose or spongy texture and linear bladeless leaves submersed, occurs eastward ; 



