324 ORDER 135. ilYDROCUARIDACE^E. 



3 S. lanceoliita L. Leaves lance-oblong, rarely linear, tapering to the lung petiole, 



scape branched ; 2 3f ; achenia obovate-falcate. Swamps, Va. to Fla. 



4 S. heterophy lla Ph. Leaves linear-lanceolate, rarely some of them with 1 or S 



base lobes ; scape simple, weak; achenia narrow, long-beaked. Common S. and W. 



5 S. gramiiiea MX. Scape erect, slender, 5 W ; leaves lance-ovate to linear, rarely 



sagittate ; pedicels all equally Blender ; achenia beakless ; flowers 8 9" diameter. 

 /3. platj/phylla. Leaves lance-ovate ; flowers larger, 1' broad. South. 



6 S. pusilla N. Scape shorter than the leaves (2 40; leaves linear, shorter than the 



petioles ; flowers few, the fertile but one, deflexed ; stamens about 7. N. J., and S. 



7 S. natans MX. Scape mostly erect, 3 6' ; leaves oval-lanceolate, floating, obtuse. 



3 veined ; lower pedicels longest ; achenia angular, short-beaked. South. 



5. TRIGLOOHIN, L. ARROW-GRASS. Sepals and petals concave, 

 deciduous (green). Sta. 6, very short, anth. large, extrorse. Ova. 1-ovuled, 

 3 6, united and indehisceut in. fruit. U Leaves all radical, grass-like 

 Scape jointless, and bractless. Flowers small. July. 



1 T. maritimum L. Fruit ovate-oblong, grooved, of 6 united carpels; scape 



longer (9 18') than the leaves. Salt marshes and Lake shores, northward. 



2 T. pal ustre L. Fruit nearly linear, of 3 united carpels ; scape scarcely longer 



than the numerous and very narrow leaves. Marshes, N. Y., and N. 612'. 



6. SCHEUCHZERIA, L. Sep. and pet. oblong, acute, persistent. Sta. 

 6, with linear anthers. Ovaries 1-2-ovuled, becoming flattened inflated 

 capsules. U Leaves cauline, sheathing at base, linear. 



S. palustrls L. A rush-like plant, in swamps, Vt. to 111. (J. Wolf). Root-stock hori- 

 zontal, fleshy. Stem If. Leaves semicylindric, 4 8'. Flowers yellowish green, in a 

 bracted raceme. Stamen* large, exserted. July. 



ORDER CXXXV. HYDROCHARIDACE^E. FROGBITS. 



Aquatic herbs, with parallel- veined leaves and diclinous flowers solitary 01 

 spicate. Perianth regular, 3-6-parted, the inner segments petaloid. Sta- 

 mens 3 12. Ovary adherent, 1-9-cclled, with 3, 6, or 9 stigmas. Fruit 

 dry or juicy, co-seeded, indehiscent 



* Leaves all radical, roundish, floating in stagnant waters LIMNOBIUM. 1 



* Leaves opposite or verticillate in 3's and 4's on the stems, submersed AKACHAKIS. 2 



* Leaves all radical, grass-like, in water VALLISNKKIA. 3 



1. LIMNOBIUM, Rich. FROG'S-BIT. Fls. i> . Spathes subsessile, the 

 $ 1-leaved, about 3-flwd., the ? 2-leaved, 1-flwd. Perianth showy, white. 



Sta. 6 12 (mere rudiments in $ ). Ov. 6-9-celled, becoming a co-seeded 

 berry. V? Stoloniferous. Lvs. on long stalks, subco relate. July, Aug. 

 L. Spoil ta. Rich. Lake Ont. (rare), and S. Lvs. 1 1}', purplish and spongy beneath 



2. ANACHARIS, Rich. DITCH Moss. Fls. $ 5 $ , solitary. Spatlio 

 axillary, bifid. Perianth 6-parted, colored, small, the fertile excessively 

 produced above the adherent ovary into a capillary tube. Style capillary, 

 with 3 large stigmas. Fruit few-seeded. H ? Wholly submersed. Aug. 

 A. Canadensls Plane. Stems filiform, long, forking; very leafy ; leaves linear-ob- 

 long, serrulate, 510" ; tube of the dingy-white fls. 2 10' long I Streams and bogs. 



