PETALOIDE^E. 137 



4. Ii. gibba (gibbous D.) Stagnant waters, rare. Fronds 

 similar to but larger than L. minor, thick, flat on the upper but 

 nearly hemispherical and cellular on the under side ; a single 

 root descends from each frond. Flower with 2 stamens. Be- 

 tween Bishopsteignton and Kingsteignton. (E. B. t. 1233.) A. 



OED. CV. NAIADACEJE. 

 FOTAMOGETON. PONDWEED. 



1. P. densus (opposite-leaved Pondweed.) In ditches. 

 Leaves submersed, thickly crowded together, opposite, pellucid, 

 clasping the stem, pointed-ovate or lanceolate. Spikes stalked, 

 4-flowered. Flowers green. River Clyst, by St. Mary Clyst 

 Bridge, Fl. D. (E. B. t. 397.) P. vi. vn. 



2. P. pectinatus (fennel-leaved P.) In rivers, ponds, and 

 salt-marshes. Leaves alternate, submersed, very narrow and 

 pointed, sheathing at the base, growing from the slender stems 

 in opposite directions. Flower- spikes rising above the water. 

 Flowers of an olive-green, in interrupted clusters. G-oodrington 

 Marsh. (E. B. t. 323.) P. vi. vn. 



3. P. pusillus (small P.) In ditches and stagnant waters. 

 Leaves submersed, alternate, narrow-linear, sessile. Flower- 

 staUks bearing a spike of 3 or 4 greenish flowers. The var. j3, P. 

 compressuSy E. B. t. 418, with broader leaves and attaining a 

 greater size in all its parts, is united with this by Hooker and 

 Arnott. Ditches near Powderham. Exminster marshes. (E. B. 

 t. 215.) P. vi. vn. 



4. P. crispus (curly P.) In ditches and streams. Leaves 

 alternate, pellucid, linear-oblong, blunt, waved, and serrated, 

 sessile. Flower- stalks longer than the leaves, bearing a lax spike 

 of purplish-brown flowers. Mill-stream near Totness. River 

 Exe. (E. B. t. 1012.) P. vi. 



5. P. perfoliatus (perfoliate P.) In lakes, ditches, and 

 streams. Stem long and slightly branched. Leaves all sub- 

 mersed, alternate, ovate heart -shaped, clasping the stem, pellucid. 

 Flower- spikes short ; flowers dullish purple. River Exe, between 

 Topsham and Exeter, Fl. D. (E. B. t. 168.) P. VII. 



6. P. lucens (shining P.) In lakes, pools, and streams. 

 Stems long, round, and leafy. Leaves submersed, alternate, pel- 

 lucid, stalked, ovate or lanceolate, accompanied by a winged 

 stipule. Spike dense and many-flowered. Flowers dark green. 

 Pools on Haldon. (E. B. t. 376.) P. vi. 



