140 PERNS OE GREAT BRITAIN. 



dust-like seeds. The plant likewise forms buds, and 

 seems chiefly propagated by their means. These curious 

 little stalked buds consist of three or four egg-shaped 

 leaves of different sizes, placed in the axils of the leaves, 

 chiefly towards the summits of the branches. 



Order III. MARSILACE^.— PEPPERWORTS. 



1. IsoETEs (Quillwort). 



1. I. lacustris (European QuiUwort or Merlin's Grass). 

 — Leaves awl-shaped, bluntly four-sided, with four- 

 jointed tubes. The QuiUworts are aquatic plants, and 

 our only native species of the genus is abundant at the 

 bottoms of lakes and ponds in some hilly districts. The 

 plant renders such a spot very beautiful, as, when seen 

 through the crystal waters, it looks like a meadow of the 

 richest green hue, and, as it is perennial, it adorns them 

 at all times of the year. It occurs in lakes, reservoirs of 

 water, and on marshes and other inundated places in the 

 north of England and Wales, and is frequent in some of 

 the Scottish lakes. Mr. Knapp, remarking on the soil 

 of the Highlands, says that a considerable portion of it 

 is formed chiefly by the granite of rocks, the felspar, 

 quartz and mica having been disintegrated by the 

 elements, and mingled with a little vegetable earth ; and 

 that the roots of plants and the lower leaves are gene- 

 rally sprinkled with glittering specks of mica. " So 

 general," says this writer, " is the difiusion of this mica- 

 ceous earth through Scotland, that we have found the 



