As a rule this plant grows by the seashore, where, by means of its fibrous roots, it may play a useful part in helping to bind the shifting sand. The Variegated Horsetail is not exclusively maritime, however, for it sometimes grows by the sides of rivers and ponds. The barren and fertile stems closely resemble one another, and they are very nearly prostrate in habit. As a rule they are about a foot in height, and the stems have from four to ten ridges. The upper part of the stem is usually unbranched, but whorls of branches occur towards the base. The sheaths, which, as already stated, are green below and black above, fit very closely to the stem. The black teeth have white margins, and terminate in bristle-like points. The cones are borne at the summit of the fertile stems, and are comparatively small. The Variegated Rough Horsetail occurs chiefly, though not exclusively, in the North of England. [Illustration: Equisetum hyemale. The Dutch Rush.] _Equisetum hyemale._—In this case the specific name is a Latin adjective which means “pertaining to winter,” an allusion to the fact that the plant is to be found all through this season. The Rough Horsetail or Dutch Rush. This is quite the most distinct of all the Horsetails. There are none of the whorled branches which are so familiar in the other species, and it is only now and again that even a single branch is produced from the base of one of the sheaths. There is a strong resemblance between the barren and the fertile stems. These are both tall and very erect, usually running up to the height of two or three feet. The stem is very rough to the touch, and is marked with from fourteen to twenty ridges. The edges of these ridges are thickly covered with flinty particles. The sheaths of the Dutch Rush clasp the stem of the plant very closely. The fertile cone is small, and is placed at the top of the stem. The Rough Horsetail is not a very common species, but is abundant on the Continent, especially in Holland and Germany, where it is largely employed for the fixing of the soil of embankments. The Rough Horsetail is very useful for polishing wood. CHAPTER XIII FERN COLLECTING AND PRESERVING