O'J ENGLISH BOTANY. 



and has a distinct tooth on the upper mar2;in, and is miich more 

 convex on the lower, and in all the specimens I have seen is more 

 or less crenulatcd or subtuberculated on the back; the beak forms a 

 continuation of the upper margin, instead of being in the middle of 

 the apex. 



I am indebted to the Rev. Kirby Trimmer for fresh specimens of 

 this plant. 



ITair-leaved Pondweed. 



Froncli, Potamot dfeuillcs capillaires. German, Haarfurmiges Samhraut, 



Section IV.— PECTINATI. 



Leaves all similar, alternate, the uppermost ones opposite, sheathing 

 at the base, linear or setaceous, with flat vernation, 1- to 3-ribbed. 

 Stipules adhering to the petiole of the leaf to form the sheath. 

 Peduncles terminal or pseudo-lateral. Spikes few-flowered, often 

 elongated, interrupted. 



SPECIES XXn.— POTAMOGETON PECTINATUS. Linn. 



Plates MCCCCXXI. MCCCCXXII. MCCCCXXIII, 



Billot, Fl. Gall, et Germ. Exsicc. No. 3250. 



Stem cylindrical or subcompressed, slender, dichotomous or trichoto- 

 mous. Leaves all similar and subtranslucent, with sheathing petioles, 

 the earlier ones linear or broadly linear, the upper narrowly linear or 

 setaceous, acute, with only 1 longitudinal rib, or the lower ones with 

 3 to 5 ribs, many of the leaves with 1 or 2 branches in their axils. 

 Stipules rather long and narrow, subscarious, united to the sheathing 

 petiole of the leaf, with only the apex free. Peduncles terminal or 

 pseudo-lateral, longer than the spike, generally 3 to 5 times as long, 

 liliform, not thickened upwards. Sepals with their lamina suborbicular, 

 reniform. Fruiting-spike rather short, slightly interrupted, few- 

 flowered, often with tlie lowest whorl or two whorls of flowers distant 

 from the others ; the terminal ones subapproximate. Fruit large, olive 

 tinged Avith orange-brown, scarcely compressed, straight or slightly 

 convex on the upper margin, half obovate-semicircular and indis- 

 tinctly 3-keeled on the back, with a very short beak forming a con- 

 tinuation of the upper margin. Plant dull olive-green, becoming 

 darker when dried. 



