“ NAIADACEE. 51 
mucronatus. Sometimes, however, the two are extremely difficult 
to distinguish in the dried state when not in flower or fruit, and they 
are probably distinct only as subspecies. 
Small Pondweed. 
French, Potamot fluet. German, Kleines Samkraut. 
I SPECIES XXI—POTAMOGETON TRICHOIDES. Chau. 
Pirate MCCCCXX. 
Reich. Ic. Fl. Germ. et Helv. Vol. VII. Tab. XXT. Fig. 34, and Tab. XXII. Fig. 35, 
‘ Billot, Fl. Gall. et Germ. Exsice. No. 654. 
P. monogynus, Gay in Coss. & Germ. Fl. Par. ed. i. p. 572. 
iP, tuberculatus, “ Ten. & Guss. in Act. Soe. Borb. Vol. V. p. 430” (Coss.). 
_ Stem subcylindrical, not compressed, filiform, repeatedly dichoto- 
‘mous or trichotomous. Leaves all similar, sessile and semi-amplexicaul, 
linear-setaceous, not narrowed towards the base, acute, with only 1 
Jongidinal rib; many of the leaves with 1 or 2 branches in their 
axils. Stipules small, subacute, subscarious, with numerous slender 
longitudinal fibres. Peduncles terminal from the forks of the stem, 
much longer than the spike (usually 6 or 8 times as long), filiform, 
‘not thickened upwards. Sepals with their lamina suborbicular. 
‘Pistil solitary. Fruiting-spike oblong-ovoid or subglobose, usually 
slightly interrupted, very few-flowered. Fruit rather small, greenish- 
olive, slightly compressed, not acuminated, nearly straight along the 
‘upper margin, where there is a prominent tooth near the base, semi- 
| circular and bluntly keeled on the back, terminated by a very short 
| straight beak forming a continuation of the upper margin; keel nearly 
entire, subdenticulate or tuberculate. Plant deep dull green, becoming 
much darker when dried. 
In ponds, ditches, and slow water, in muddy soils. Discovered by 
the Rey. Kirby Trimmer at Framingham Earl, Norfolk: the following 
other stations are given in that gentleman’s “ Flora of Norfolk” :— 
“Swardiston. Swanesthorpe. Alpington. Marlingford. Lyng. 
Alburgh. Pulham. St. Mary the Virgin. Ina slow water ditch near 
' the railway station, Tivetshall. Walpole St. Peter (Mr. Lowe).” 
England. Perennial. Summer. 
Very similar in habit to P. pusillus, var. tenuissimus, but more 
_ copiously branched, with the branches divaricate. The leaves narrower, 
- more slender and rigid, rarely above 1 to 1} inch long: the peduncles 
_ are much longer, frequently 2 inches long: the flowers are fewer, and 
| appear to have always only one pistil: the fruit is about ;/5 inch long 
| H 2 
