Ruppia.'] 



TETRANDRIA — TETRAGYNIA. 71 



Ditches and slow streams in many parts of England ; Anglesea. Near 

 Glasgow and Forfar ; in the Gaddie, at Premnay, Aberdeenshire. FL 

 July. If. — " This does, in some situations, much resemble P. lucens. 

 The coriaceous floating leaves are nearly as acute as the lower ones, 

 diftering only in their firmer texture and in being stalked, the ribs, shape, 

 and size are much the same in both. The lateral ribs or nerves are by- 

 no means separate to the base of the leaf, but arise from various parts 

 of the central rib ; some of them one-third the length of the leaf from 

 its base ; they are from 6 — 7 in number on each side, 2 of them more 

 evident than the rest : flower-stalk not thickened upwards." {Wilson in 

 litt.) It is remarkable for its reddish-olive colour, and is perhaps better 

 known by its general aspect, size, and hue, than by any character that 

 can be applied to it. To me, the above species with floating leaves seem 

 gradually to pass into one another. 



14. P. ndtans, L. {sharp-fruited broad-leaved Pond-xceed); 

 lower leaves linear submembranaceous or wanting', upper ellip- 

 ticalcoriaceousfloating,allon long stalks many-nerved distinctly 

 cellular, fruit carinated. E. Bot. t. 1822. E. FL v. i. p. 228. 



Stagnant waters and slow streams, frequent. FL June, July 11 . — Very 

 variable, in the size of the ])lant, and in the shape of its floating leaves, 

 which are more or less elongated, sometimes linear-lanceolate, obtuse at 

 the base or decurrent at the footstalks. The lower leaves appear to me 

 to difter from the submersed leaves of all the others in having their sub- 

 stance composed of the same small, but distinct, cells or reticulations as 

 the floating ones. These submersed leaves are frequently wholly want- 

 ing, es|)ecially when the plant grows in very shallow water. Chamisso 

 and Schlechtendal describe the lower petioles as leafless, but this assured- 

 ly is not always the case. 



20. Ruppia. Linn. Ruppia. 



1. R. marifima, L. (sea Ruppia). E. Bot. t. 136. HooJi. in 

 FL Land. t. 50. 



Salt-water pools, and ditches. FL July, Aug. %.— Stems slender, fili- 

 form, flesuose, branched, leafy. Leaves linear-setaceous, with sheaths 

 sometimes narrow and small, at other times large and inflated. Spadix 

 at first very short, included in the sheath or spatlia, with 2 green flowers 

 one above another on opposite sides, and quite destitute of perianth. An- 

 thers large, sessile, subquadrate, bursting horizontally, 1 -celled. Mertens 

 and Koch say that each pair is, in fact, the 2 cells of 1 anther; and that 

 there are in reality, but 2 sessile stamens. Pollen, a tube with 3 globules, 

 1 in the middle and 1 at each end of the tube. Germens resembling 

 4 minute tubercles in the centre between the anthers. At the time of 

 ■flowering, the spadix lengthens remarkably, to the height of 5 or 6 inches 

 or more, and becomes spirally twisted, so as to bring tiie blossoms to the 

 surface of water : but Mr Wilson observes the fruit to be submersed in 

 every stage. When the germens swell, their base is elongated into a 

 footstalk, one or two inches long. Each then becomes an oblique, ovate, 

 acuminated drupe. This drupe is sometimes more beaked than at other 

 times, and the sheaths of the leaves are sometimes but little dilated ; then 

 the plant becomes R. rostellata of Koch, and of Reichenbach in his 

 Iconog. t. 17-i./. 306, which indeed is the more common state of the 

 plant with us. 1 have onlv seen such large sheaths as are figured for the 

 true B. maritima, £«/««. "(Reichenb. Iconog. t. n\. f. 307.), on sped- 



