494 HYDROCHARIDACE.E. (FROG's-BIT FAMILY.) 



Var. flItitaxs, with lance-linear floating leaves, has been found in Missouri and 

 westward; and Yar. granihs, with leaves 9"- 12 "wide and 9 long, branched 

 scape, and fruit-heads 9" diameter, grows farther south. — This species shows 

 9-12 stamens in the fertile, and some sterile pistils in the sterile flowers; and 

 thus connects with Echinodorus. 

 * * Filaments very short, with enlarged mostly glandular base: scape more simple. 



4. S. heterophylla, Pursh. Scape weak (3' -2° high), at length pro- 

 cumbent ; bracts roundish, obtuse ; flowers of the lowest whorl fertile and al- 

 most sessile; the sterile on long pedicels ; filaments glandular-pubescent; ache- 

 nia narrowly obovate with a long erect beak ; leaves lanceolate or lance-oval, 

 entire, or with one or two narrow basal sagittate appendages. — Rather common, 

 at least southward. — Var. elliptica has broad leaves (sometimes 6' long 

 and 5' wide), either obtuse or cordate at the base, or sagittate. — Var. rigida 

 (S. rigida, Pursh, on the Niagara and along the Great Lakes), the tallest form, 

 has stout petioles and rigid narrowly lanceolate blades, acute at both ends. — 

 Var. angustif6lia has nearly linear leaves. 



5. S. graminea, Michx. Scape very slender, erect (3' -2° high); the 

 lower whorls fertile ; bracts rather obtuse and usually connate ; pedicels all 

 slender, the sterile and fertile of equal length ; filaments glandular-pubescent ; 

 achenia small, narrowly obovate, almost beakless ; leaves varying from ovate- 

 lanceolate to linear or reduced to broad and acute phyllcdia (when it is S. 

 acutifolia, Pursh) ; scarcely ever sagittate. (S. simplex of Amer. authors; not 

 of Pursh, whose plant of this name is a dioecious form of S. variabilis.) — Rather 

 common, especially southward. — Flowers and fruit-heads smaller than in any 

 of the foregoing; except in the var. platyphylla, which is found farther 

 south, and has leaves 6' -9' long and 3' -4' wide ; flowers 1' wide, on pedi- 

 cels 1^' -2' long. 



6. S. pusilla, Nutt. Scape (l'-3' high) weak, reclining in fruit; bract 

 single, clasping ; one or two Avhorls only, of which but a single flower is fertile, 

 recurved in fruit ; stamens about 7, with glabrous filaments; achenia obovate, 

 with an erect beak and three notched dor-al ridges. (Alisma subulata, Pursh.) 

 — Inundated shores, from Eastern New Jersey ( C. F. Austin) and Philadelphia 

 southward near the coast. 



S. natans, Michx., closely allied to the last, is only found farther south-, 

 it is a larger plant with long phyllodia, or oval floating leaves, glabrous fila- 

 ments, and obovate short-beaked achenia, with 5-9 crenate angles, — by which 

 structure it is nearly connected with Echinodorus. 



Order 112. HYMiOCHARIDACE^. (Fkog's-bit Family.) 



Aquatic herbs, with dioecious or polygamous regular flowers on scape-like 

 peduncles from a spathe, and simple or double floral envelopes, which in the 

 fertile flowers are united into a tube and coherent with the 1 - 3-celled ovary. 

 Stamens 3- 12, distinct or monadelphous : anthers 2-celled. Stigmas 3 

 or 6. Fruit ripening under water, indehiscent, many-seeded. Seeds as- 

 cending, without albumen : embryo straight. 



