PODOSTEMACE^. 113 



i). M. tetiellum Big. : stem simple, nearly leafless, erect, somewhat root- 

 ing at base ; floral leaves minute, entire ; flowers alternate ; petals linear^ 

 oblong; carpels smooth and even. 



Borders of ponds. N. Eng. and N. Y. July. %. — Scapes several from the 

 same rhizoma, 4 — 12 inches high, with numerous small scales. Flowers minute, 

 purplish. Leqflless Water Milfoil. 



3. HIPPURIS. lAnn.—MeiTe's-tsiil 



(From the Greek iitttos, a ?iorse, and ovpa, a tail ; from a fancied resemblance 

 of the plant.) 



Tube of calyx adnate to the ovary; limb minute, entire. 

 Petals none. Stamen 1, inserted into the margin of the calyx. 

 Style filiform, received into a groove of the anther. Fruit 1- 

 seeded, crowned with the margined limb of the calyx. 



H. vulgaris Linn. : leaves in whorls of 8 — 12, linear, acute, callous at 

 the tip. 



Ponds and lakes. Labrador and Subarct. Amer. to Penn. Aug. %. — Stem 

 12 — 18 inches high, simple, erect. Leaves mostly in whorls of 8. Flowers at 

 the base of the upper whorls, one to each leaf, sessile, minute. 



Common Mare's-tail. 



4. 1 CALLITRICHE. iiwi.— Water Starwort. 



(From the Greek KaWos, beautiful, and 6pt^, hair ; in allusion to its long and 

 slender stems.) 



Flowers perfect or imperfect. Bracts 2, opposite, petaloid. 

 Calyx (corolla of some) inconspicuous. Petals none. Sterile 

 Fl. Stamens 1, (rarely 2,) Avith the filament filiform and ex- 

 serted ; anthers reniform. Fertile Fl. Ovary 4-lobed. Cap- 

 sule compressed, 4-celled, indehiscent. 



C. verna Linn. : leaves 3-nerved; upper ones aggregated, broader ;* fruit 

 sessile, with 2 bracts at the base, each carpel bluntly keeled on the back. 



var. 1. vulgaris: leaves all elongated and obovate. 



var. 2. intermedia : upper leaves spatulate-obovate ; lower ones linear, 

 C. intermedia Willd. C. heterophylla Pitrsh. 



var. 3. linearis: leaves all linear, or the upper ones linear- elliptic. 

 C. autumnalis Mich. 



var. 4. terreslris : stem procumbent, rooting in the mud ; leaves linear oi 

 eUiptic-oblong. C ierrestris Raf. 



Ponds and slow-flowing streams, or in muddy banks. N. S. Some varieties 

 throughout the U. S. May — Aug. (!)• — Stems slender, varying in length with 

 the depth of the water, growing in tufts or patches. Flowers very minute, white. 

 I readily adopt the views of Darlington and Torrey in regard to this very 

 variable plant. Common Water Starwort. 



Order XLV. PODOSTEMACE^.— Podostemads. 



Flowers usually perfect, naked, bursting through an irregu- 

 larly lacerated spathe. Stamens 1, 2, or many, often monadel- 



