82 



ALISMACEAE (WATER-PLANTAIN FAMILY) 



B4. S. latifolia. 

 Achene x 3. 



35. S. Engel- 

 maDDiana. 

 Achene x 3. 



win<^ed on both margins, with a curved usually horizontal beak. (S. variabilis 

 En'^'ehn ) — In water or wet places, very connnou ; exceedingly variable as to 

 leaf-contour. Fig. 34. The following forms, although ill defined, 

 are in most instances recognizable: Forma OBxtJSA (Muhl.) 

 Kobinson. (^S". obtusa Muhl.) Leaves very broad, sagittate, ob- 

 tuse. Forma hastAta (Fursh) Kobinson. {S. hastata Pursh.) 

 Leaf-blades and their basal lobes oblong-lanceolate, acute. Forma 

 gkAcilis (Pursh) Kobinson. (S. gracilis I'nrah.) Leaf -blades and 

 their basal lobes narrowly linear. Forma diversifolia (Engelm.) 

 Robinson. (S. variabilis, var. Engelm.) Leaf-blades partly sagit- 

 tate and partly lanceolate or elliptic without basal lobes. 

 Var. pub^scens (Muhl.) J. G. Sm. Robust, pubescent, broad- 

 leaved; bracts shorter than in the other forms, 6-9 mm. long, 

 broadly ovate, obtusish, and very pubescent. —'^. J. and Pa. to 

 N. C. 



3. S. Engelmanniana J. G. Sm. Slender; lobes of the 

 sagittate leaves very narrowly linear (1-3 mm. wide) ; achene 

 narrowly cuneate-obovate (4 mm. long), the beak elongated, erect 

 or recurved, the sides usually strongly 1-3-crested. {S. variabilis, 

 var. gracilis Engelm.)— About ponds, etc., "N. H." and Mass. 

 to Del. Fig. 35. 



4. S. arifblia Nutt. Monoecious, glabrous; scape 2-4 dm. 

 high, simple or rarely branched ; fertile whorls I-(rarely)3 ; fertile pedicels 

 8-11 mm. long ; leaf-blades sagittate-hastate, ovate, acute ; achenes winged all 



round, bearing at the upper inner angle a minute erect beak. — 

 Que. to centr. Me., Vt., Ct., Mich., Kan., Dak., and westw. — 

 When in deep water producing lance-linear phyllodia at the base 

 and developing elongated petioles of the blade-bearing leaves 

 (^S. cuneata Sheldon). Fig. 36, 



5. S. brevir6stra Mackenzie & Bush. Very stout ; scape 6-12 

 dm. high ; leaf-blades all sagittate, basal lobes ovate-lanceolate, 

 acute, about as long as the terminal portion ; inflorescence simple 

 ^T slightly branched, 2-5 dm. long ; bracts lanceolate, attenuate ; fruiting pedi- 

 cels 1-2 cm. long ; fruiting heads 2-3 cm. in diameter; achenes cuneate-obovate, 

 with dorsal wing prominent ; beak suberect, but little surpassing the wing at 

 the summit. — Sloughs and bottoms, Ind. to Kan. 



6. S. lancifblia L. Scape 8-15 dm. high, with several of the lower whorls 

 fertile ; leaves lanceolate or lance-oblong, rarely linear, all loith a tapering base, 

 thick or coriaceous (1.5-4.5 dm. long on a long and stout petiole, never sagittate), 

 the nerves mostly arising from the very thick midrib ; bracts ovate, acute or acu- 

 minate ; pedicels slender, the fertile scarcely shorter than the 

 sterile ones ; filaments pubescent ; achenes falcate, winged on the 

 back, pointed with an incurved beak. — Swamps, Md. to Ky., Mo., 

 andsouthw. (W.I.) Fig. 37. 



7. S. ambigua J. G. Sm. Scape 4-6 dm. high; leaves as in 

 the preceding ; raceme simple ; pedicels 1.5-2.5 cm. long ; bracts 

 lanceolate, small (8 mm. long) ; filaments glabrous ; achenes 

 with a short incurved beak, scarcely winged. — Borders of ponds, etc 

 and souhtw. 



* * Filaments very short, with enlarged mostly glandular base; anthers ovate or 

 short-oblong ; fruiting heads small ; bracts more or less connate; leaves very 

 rarely sagittate. 



8. S. heterophylla Pursh. Scape weak (1.5-8 dm. high), 

 at length procumbent ; leaves lanceolate or lance-oval, entire, 

 or with one or two narrow basal sagittate appendages ; bracts 

 roundish, obtuse ; flowers of the lowest whorl fertile and almost 

 sessile ; the sterile on long pedicels ; filaments glandular- 

 88. S. heterophylla. pubescent ; achenes narrowly obovate with a long erect beak. — 

 Achene x 3.' N. E. to Fla. , w. to Minn, and Mo. — Varies as to foliage, the 



S6. S. arifolia. 

 Achene x 3. 



. S. lancifolia. 

 Achene X 3. 



Kan. 



