WATER TLANTAIN FAMILY. 455 



E. rostr^tus, Engelm. Leaves broadly heart shaped (I'-o' long, not 

 mc'hidiiig the petiole), shorter than the erect scape, wiiich bears a panicle 

 of prolifennis umbels ; flower almost V wide ; 12 stamens ; akenes beaked 

 wiLh slender styles. 111., W. and S. *■ ® 



E. radicans, Engelm. Leaves broadly heart-shaped and larger (3'-8' 

 wide), which are very open or almost truncate at base ; the creeping 

 scapes or stems becoming P-4'^ long and bearing many whorls ; flowers 

 I'- J broad ; akenes short-beaked. 111., W. and S. 21 ? 



3. SAGITTARIA, ARROWHEAD. (From the Latin for arrnu; 

 on account of the sagittate leaves which prevail in the genus.) In 

 shallow water ; flowers all summer. 2t 

 * Filaments long and slender, i.e. as long as the linear-ohlong anthers. 



S. variabilis, Engelm. The common species everywhere, exceedingly 

 variable ; almost all the well-developed leaves arrow-shaped ; filaments 

 nearly twice the length of the anthers, smooth ; sepals reflexed after 

 flowering ; akenes broadly obovate, with a long and curved beak ; calyx 

 remaining open. The lobes of the leaves are sometimes very narrow- 

 linear (var. gracilis, Engelm), and sometimes the petioles, upper part 

 of the scape, the bracts, and sepals are pubescent (var. pubescens, 

 Engelm). Other well-marked forms occur. 



S. Montevidensis, Cham. & Schlecht. From S. Ainer., now frequently 

 grown in aquaria ; distinguished from the above by a deep purple spot at 

 the base of the flower inside, thick pedicels of the pistillate flowei's, and 

 sepals erect after flowering. 



S. Iancif61ia, Linn. Common from Md. and Ky., S. ; with the stout 

 leaves l"-3° and scapes 2°-5° high, the coriaceous blade of the former 

 lance-oblong and always tapering into the thick petiole, the nerves nearly 

 all from the thick and prominent midrib. 



S. calycina, P>ngelm. Along rivers, often much immersed; many of 

 the leaves linear or with no blades ; the others mostly halberd-shaped ; 

 scapes weak, 3'-9' high ; pedicels with fruit recurved ; filaments roughish, 

 only as long as the anthers ; akenes obovate, tipped with short horizontal 

 style ; calyx appressed to head of fruit and partly covering it ; the fertile 

 flowers show 0-12 stamens, the sterile occasionally some rudiments of 

 pistils. Me., W. and S. 



* * Filaments very short and broad. 



S. heterophylla, Pursh. Scapes 3'-2° high, weak ; the fertile flowers 

 almost sessile, the sterile long-pediceled ; filaments glandular-pubescent ; 

 akenes narrow-obovate, with a long, erect beak ; leaves linear, lanceolate 

 or lance-oblong, arrow-shaped with narrow lobes or entire. N. Eng., 

 W. and S. 



S. graminea, Michx. Common S. ; known from the foregoing by 

 the slender pedicels of both kinds of flowers ; small, almost beakle.ss 

 akenes; and leaves rarely arrow-shaped; the phyllodia flat. N. Eng., 

 W. and S. 



S. thies. Watson. N. Eng. to N. J., in shallow water ; scape 0'-20' 

 liigli ; pliyllodia terete, acutely attenuate upwards, very rarely with a 

 narrow blade; pedicels all very slender and spreading, in 1-3 whorls; 

 filaments 12, dilated and i)ubescent ; akene obovate, with an erect beak, 

 the margins cr6.nate-crestcd. 



S. nutans, Michx., vfir. lorata, Chapm. Known by the small size 

 (l'-3' high), few flowers, usually oidy one of them fertile and recurved 

 in fruit; stamens only about 7, with glabrous fihunents; akenes obovate, 

 with erect beak ; and leaves without a true blade. N. Y., S., near the 

 coast. 



