494 , HYDROCHARIDACEJE. (FROG'S-BIT FAMILY.) 



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

 westward; and Var. GRANDIS, 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. heteroph^lla, 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- 

 ma 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. ELL^PTICA has broad leaves (sometimes 6' long 

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

 (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 phyllodia (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. PLATYPHY"LLA, which is found farther 

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

 cels l'- 2' long. 



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

 single, clasping ; one or two whorls 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 dorsal 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. HYDROCH ARID ACE. 12. (FROG'S-BIT FAMILY.) 



Aquatic herbs, ivith 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 - B-celled ovary. 

 Stamens 3 - 1 2, distinct or monadelphous : anthers 2-celled. Stigmas 3 

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

 cending, without albumen : embryo straight. 



