258 On American Species of the Qenus Potarnogeton. 



the outline is not dissimilar from that of the nutlets of P. pv stilus. 

 but the sides are flattish, and the back is acute. Pursh omits, in 

 his Flora, the customary mark of having seen this species living, 

 repeating there merely the character and habitat given in Mi- 

 chaux's Flora to the P. gramineus of that work : and there is 

 no specimen of it in his herbarium. Michaux's plant is therefore 



who had seen a single nutlet 



a 



/< 



though this differed a little, in its larger dimensions, from the 

 fruit of his specimens of P. pauciflorus from the Sandwich Isl- 

 ands, both might well belong to the same species. 



Potamogetox TRicHoiDEs. (Cham, and Schlecht.): caule tere- 

 tiusculo ramosissimo ; foliis omnibus submersis membranaceis 

 longiusculis concavo-convexis setaceo-linearibus versus apicem 

 sensim levissime basique brevissime attenuatis sessiiibus, apice 

 acutissimis, uninerviis, aveniis, reticulato-cellulosis ; stipulis lin- 

 guiformibns amplectentibus acutis ; pednnculis elongatis; spicis 

 subinterruptis, vel saepius confertis abbreviatis; fructibus recenti- 

 bus oblique lunato-ovatis, dorso latiori tricarinatis. carina media 

 semicircular! obtusiuscule subalato-carinata, lateralibus discretis 

 obtusinsculis, lateribns planiusculis medio impressis, facie obtusa 

 basin versus unidentata, stylo faciali brevissimo. P. trichoides, 

 Cham, and Schlecht. in Linncea, 2, p. 175, t. iv, f. 6. Koch. 

 Syfi., p. 677. A. Gt\! Man. Bot., p. 457. P. pusUlus, £ e 

 part. Mert. <$■• Koch. 1, p. 857, e Chamiss. P. pusillus, var. 

 Oakes in sched. ohm ! 



Hab. Ponds. Near the Notch of the White Mountains, in 

 the Trout-pond, abundant, and first detected there by the late Mr. 

 Oakes, and Dr. Robbins of Uxbridgo. Also in Long pond, 

 Tewksbury. Root creeping, branched, geniculate, or the stem 

 itself prostrate and performing the function of a root. Stem 

 slender, terete; much- and spread-branched below, rather distantly- 

 branched above : the branches repeatedly ramulose • 12-lS inches 

 long. Leaves rather long, delicate, pale-green; a little concave 

 above, but appearing roundish in a cross-section ;' setaceous-linear, 

 slightly and shortly tapering at base, and sensibly so above to the 

 very acute tip : one-nerved; veinless ; reticulate-cellulose: those 

 of the stem about 2 inches long by £ to J of a line wide, but 

 those of the branches much smaller. Stipules rather firm, green, 

 3-4 lines long, largest at the lower part of the stem. The elon- 

 gated, commonly simple apex of the stem serving as peduncle, 

 and a little thickened immediately below the spike; 3-6, or more 

 inches long. Spikes a little elongated and interrupted, but very 

 commonly abbreviated and somewhat capitate, few-flowered. 

 Nutlets obliquely lunate-ovate, a little compressed, tricarirmte, the 

 middle keel semicircular, narrowly winged, obtusish, sometimes 

 a little sinuate ; the lateral ones distinct, (and also sometimes sin- 



