482 



CY. NAIADACE^. 



{^Potamogeton, 



by the lengthened peduncle^ which is sometimes slightly thicken d 

 upwards. In size it almost equals P, lucens. St/mdes larop i^ 

 ones sometimes 3 inches long, white, tmged with red, not arce 

 and without the crests or wings observable in the two next, ^ ' 



12. P. 



ifoli 



elongato-Ianceolate nearly sessile but attenuate below apiculate 

 and flat at the end, stipules winged, spike with a few sub- 

 vertlcillate distant flowers, peduncle very long thickened un 

 wards. E. B. S. t. 2847. ^" 



Lough Corrib, Galway, Ireland. IjL. 7,8. — " Nearly allied to 

 P. prcehngus, but has not the amplexicaul and hood-tipped' leaves of 

 that plant: " Bab. " The most striking character is the sino-ular and 

 prominent midrib, the central portion of which consists of three Ion- 

 gitudinal A^eins or ribs, running closely parallel with each other 

 whilst on either side are 3 — 6 ribs running closely parallel to them 

 but rather more distant from each other; the whole connected by 

 transverse veins, and in the fresh state often more than one-fourth of 

 an inch in width, the whole appearing, until closely inspected, a com- 

 pact solid midrib, on either side of v/hich are 2 — 5 fine veins, the 

 whole connected by numerous secondary veinlets," J, Kirk^ Cha- 

 misso and Schlechtendal do not consider it any way distinct from 

 the next : in both the stipules arc green, with two prominent win^s 

 or crests on the back, Mr, Borrer informs us that the Rydal Water 

 plant is P. heterophyllus, 



13. P. lucens L. (shining P.); leaves stalked elliptic-lan- 

 ceolate mucronate denticulate flat, with several opposite pairs 

 of parallel nerves springing from the midrib connected by re- 

 ticulations, stipules wlno^ed, spikes cylindrical many-flowered. 

 E. B. t. 376. 



Lakes, pools, and streams, abundant. 11. 6,7. — The largest 

 of our species, and very beautiful in the nervation of its leaves. 

 Chamisso and Schlechtendal include it in a division of the genus 

 which has sometimes floating and coriaceous leaves (folia accessoria) 

 (as it is found by Mr. Wilson at Llyn Maclog) : they change its name 

 to P. Proteus, and consider the P. heterophyllus a variety of it. To us 

 they appear distinct ; but aquatic plants of all kinds are extremely 

 liable to vary. Stipules large, with two prominent wings at the back. 

 Stem thinner than the lower part of the peduncle, which is thickened 

 upwards, and about the same length as the spike. Spikes cyhndrical, 



Nerve prominent on both sides of the leaf. Upper 

 leaves smaller than the lower ones, and all suddenly contracted 

 towards the point. — Coriaceous leaves rare, ovato-lanceolate, mode- 

 rately acute, less evidently stalked than in P. heterophyllus; foliage 

 more crowded, and stipules larger and (in proportion) narrower than 

 in that species. Spikes twice as long. Wilson^ 



r 



***** Leaves alternate^ upper ones floating, broader than the rest ; sti- 



2 inches long. 



jmles free. 



(various-leaved P.) 



adop 



e 



Pools ar 



It gn 



mft strean 



i ^ 4 



on1 

 iieekgant 



eorrt 

 pJually 1 

 liointhepi 



tein; 

 liin. and 



"J or 



ias; 



