$44 



Not useful to 

 classification. 



Half water 

 plants. 



ON FRESH-WATER PLANTS. 



thence, and never showing any leaves. The flower bud 

 must therefore be growing all the time the stem is shooting, 

 and does not appear till that stops, it is the same with the 

 leaf, which has also a peculiar stem from the root, and but 

 one leaf to each. 



It is impossible, that the formation of water plants in 

 general can be of any use to classification, or to the se- 

 lection of a natural method, as 1 once hoped it would be. 

 Complete water plants indeed are outwardly known by those 

 well acquainted with their general appearance, and with the 

 classes. But the half water plants are culled from every 

 genus, even those springing in the dryest land, yet varying, 

 it should seem, from their species by growing in the water. 

 What a light does this throw on the tises of the different 

 parts of a plant ! It is the water, which appears to operatfe 

 on the interior formation of the stems, peduncles, and ves- 

 sels of the leaf. Nor does this alteration seem to effect the 

 conformation of the fruit or flower, which are the same as iti 

 the rest of the species. Not even the seed shows to the eye 

 any difference, but into this latter fact I mean to make u 

 farther inquiry. In the veronica beccabunga, where two or 

 three are taken from many of the species growing in tolerably 

 dry soils, the whole formation of the stem is altered ; see fig, 

 3. Instead of a great portion of bark, eight or ten large aif 

 vessels supply its place. The rind is completely formed, 

 of cylinders of air and water divided. Instead of a wide 

 row of wood, it has one line and eight circular vessels of the 

 same, half wood, half clear albumen. It has indeed its 

 spiral lines within these, and its line of life naeandering in 

 the pith : but this is all in which the stem resembles the 

 usual veronicas, which are in the interior all alike, the wa- 

 ter variety excepted: and what is curious, the anagallis and 

 scutella growing only in boggy ground, not so wet as the 

 usual situations of the beccabunga, has fewer air vessels, 

 and more wood. The sisymbrium nasturtium, menyanthes 

 trifoliata, ranunculus aquatica, potamogeton pusiHum, and 

 many others equally deviate from their species, and deserve 

 the name of half-water plants, being more or less varied. 

 That these should possess the spiral is not to be wondered 

 at, since the leaives, being raised much above the water, 



require 



