137 
P. crispus. Curled Pond-weed. Fig. 1361. 
Leaves submersed, lanceolate, serrated, waved at the margins. Pools 
and ditches, June and July. Greenish. (2?) #.B.1.1012, EB. B.9. 
242. H.§ Arn. 481. Bab. 352. Lind. 249, 
P. optonGcus. Oblong-leaved Pond-weed. Fig. 1362, 
Leaves all stalked; upper ones floating, oblong-elliptical ; lower 
linear-lanceolate. Spike cylindrical, on a cylindrical stalk. Ditches and 
pools. Perenn. July. Brown. (3) 2H. B. Supp. 2849. 4H. § Arn. 
484. Bab.350. Lind. 250. 
P. pR&LONGUS. Long-stalked Pond-weed. Fig. 1363. 
Leaves narrow-oblong, stem-clasping, obtuse and hooded at the end. 
Peduncles very long, cylindrical. Pools. Perenn. J uly. Brown. 
(2) #. B. Supp. 2858. H.§ Arn.481. Bab.352. Lind.334. 
P. compressus. Flat-stalked Pond-weed. Fig. 1364. 
Leaves linear, obtuse, 5-ribbed. Stem compressed. Ditches. Perenn. 
June and July. Brown. (2) #£.B.1.418. E#. B.2.243. H. §& Arn. 
480. Bab.352. Lind. 249. 
P. GRAMINEUS. Grassy Pond-weed. Fig. 1365. 
Leaves linear-lanceolate, obtuse, 3-ribbed. Stalk shorter than the 
stipules. Ditches. Perenn. July. Brownish. (2) E.B. 1.2253. 
HE. B. 2.244. H. & Arn. 480. Bab. 353. Lind. 249. 
P. pusinius. Small Pond-weed. Fig. 1366. 
Leaves linear, obtuse, 3-ribbed. Stalks much longer than the 
stipules. Ponds and ditches. Perenn. July. Brown. (2) EB. 
1.215. #.B.2. 245. H. & Arn. 480. Bab. 353. Lind. 249. 
P. acutirotius. Sharp-leaved Pond-weed. Fig. 1367. 
Leaves linear, 3-ribbed, with many parallel veins. Stem flat. 
Ditches. Perenn. July. Brown. (2) EF. B. Supp. 2609. E. B. 
2.245*, H. & Arn. 481. Bab. 353. Lind. 333. 
P. zosteR@rouivus. Grass-wrack Pond-weed. Fig. 1368. 
Leaves broadly linear, 3-ribbed, with many parallel veins. Stalks 
swelling upward. Stem flat. Pondsandlakes. Perenn. July. Brown. 
(2) E. B. Supp. 2685. FE. B. 2. 245**. H. & Arn. 481. Bab. 
392. Lind. 249. 
P. pectinatus. Fennel-leaved Pond-weed. Fig. 1369. 
Leaves bristle-shaped, sheathing. Stipules adnate. Spike inter- 
rupted. Green. (2) EF. B.1.323. EF. B.2. 246. H. & Arn. 479. 
Bab. 354. Lind. 248. 
P. pensus. Close-leaved Pond-weed. ‘Fig. 1370. 
Leaves ovate, opposite, crowded. Stipules wanting. Ditches and 
pools. June. Brown. (3) EF. B. 1.397. E.B.2. 247. H.& Arn. 
479. Bab, 354. Lind. 248. 
T 
