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. lancifblia, 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 (i- 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 5 - its length ; leaves very various, almost always 

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

 fertile pedicels only J or 5 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 arid straight beak.) In water or wet places : 

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

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

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

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

 HAST\TA is the ordinary form, with narrow halberd-shaped or sagittate leaves 

 (including S. hastata, Pursh). Var. DiVERSirdLiA, 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 frnit-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. calycina, 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 oppressed 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. sroxGidsA, with a 

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



