442 
95. potamogetonacea:. 
inner edge straight with a tooth near its base keeled, style facial. 
—jE. B. S. 2609. R. vii. t. 26.— Ped. very short. Spikes 4—6- 
flowered. L. gradually acuminate. Styles hooked, continuing 
the inner edge of the fruit. — Marsh ditches, rare. P. VI. E. 
23. P. ohtusifolius (M. & K.) ] st. slightly compressed with 
rounded edges, I. linear 3-veined, spikes ovate dense^continuoits 
about as long as the short ped., sep. rhomboidal, fr. obovate 
keeled.—^, vii. t. 25. P. gramineiis (Sm.). E. B. 2253.— St. 
slender, much branched. Peduncles very short. L. rounded 
off to a slight point at the end, with oblong network near the 
midrib, wanting the fine parallel veins of the two preceding 
species. — Ponds and ditches, rare. P. VI. VII. E. S. I. 
24. P. Fries'ii (Eupr.) ; st. slightly compressed, I. linear 
b-veined suddenly apiculate, s/5^A:essAor^ laxh or I shorter than 
the compressed cfavate ped., sep. transversely oval, fr. obliquely 
ovate bluntly keeled. — P. compressus (Sm.). E. B. 418. R. 
viii. 24, not Fries, nor Koch. P. mucronatus ed. viii., ? Schrad. 
— Lateral veins nearer together and nearer to the margin of 
the 1. than to the midrib (rarely some 1. are 3-veined), no 
intermediate veins. — Like Sp. 21 rather than Sp. 23. — Ditches. 
P. VI. VII. E. S. I. 
25. P. jJusil'lus (L.) ; st. subterete, I. linear [usually] 3-veined, 
spikes short rather lax h or 'J shorter than the slender ped., sep. 
roundish-reniform,./V. obliqueli/ ovate bluntly keeled. — E. B. 
215. R. vii. 22. — St. slender. L. narrow, rather acute, without 
intermediate parallel veins, the lateral veins equidistant hetiveen 
the midrib and margin. Ped, scarcely compressed, not thick- 
ened, tenuissimus (M. & K.); 1. very narrow l-veined, fr. more com- 
pressed. R. vii. 22, f. 39.— 7- I'. Berchtolcli (Fieber); 1. shorter and broader, fr. 
thicker more distinctly warty. R. vii. 22, f. 37. 5. P. Sturroclcii (Ar. Benn.); 
st. very slender somewhat compressed, 1. extremely thin obtuse mucronate 3—5- 
veined; ped. very slender, beak of fr. short.] Ponds and ditcheS. 
P. VL E. S. I. 
26. P.Ti'MliLS (Wolfg. in R. & S.); st. slender compnssed,\. linear the lowest 
(soon decaying) quite obtuse the upper with long acuminate points, with 1 pair 
of well-marked lateral veins, extending almost to the apex, stip. long ojlen 
with a Inng tapering point, ped. 2—3 times as long as the rather dense spike, 
fr. oblon<; elliptic vith obscure kr.el, inner edge nearly straight. — R. vii. 23. 
■7. of B. xxxviii. (;1900) t. 407 — L. firmer and much more acute and the fr. less 
oblique than in Sp. 25. Recorded from Sussex, Warw. or Staff., Anglesea. 
P. VII. E. 
27. P. tricho'i.des (Cham. & Schleclit.) ; st. subterete, I. sub- 
setaceous l-veined finely pointed, spikes short lax long-stalked, 
fr. transversely reniform obscurely keeled, straiglU inner edge 
with a tooth near its base. — E. 13. 1420. R. vii. 21. — St. very 
