Bog-plants. The extensive areas, especially in the colder regions of the northern hemisphere, which are covered by bogs and marshes, have a highly characteristic flora which is distinct from the fully Aquatic Plants (q.v.) on the one hand, and from the ordinary terrestrial flora on the other. The most important and widely distributed of bog-plants are the bog-mosses (Sphagnum), of which the steady upward growth has formed the bulk of our peat-mosses; but higher cryptogamic plants also occur, notably the horsetails (Equisetum), and occasionally also rarer forms like Pilularia and Marsilea. Many sedges and rushes, reeds and grasses, are also highly characteristic, most of all perhaps the curious cotton-grass (Eriophorum), while heaths constantly struggle for possession of the drier and denser spots. The Bog-myrtle, q.v. (Myrica Gale) often overspreads vast areas with its low, scanty brushwood, above which rise only occasional tufts of willow, or at most here and there an alder. The insectivorous plants are perhaps the most characteristic minor denizens, sundews (Drosera) and butterworts (Pinguicula) being thickly strewn, while the rarer blossoms of the bladderwort (Utricularia) rise golden from their stagnant pools. The margins of these are fringed by the beautiful bog-bean (Menyanthes) and the smaller and less spreading forget-me-nots (Myosotis), or in spring are gay with marsh-marigolds (Caltha) and ranunculuses; while the brown blossoms of the marsh-potentilla (P. Comarum), the purplish-pink louseworts (Pedicularis), and the curious yellow-rattle (Rhinanthus) make their appearance later in summer.
The progress of agriculture completely destroys this flora, hardly a single bog-plant, save the versatile Polygonum amphibium, being able to survive thorough drainage. Many beautiful bog-plants can, however, be easily cultivated where a supply of standing water renders possible an artificial re-establishment of their natural conditions, or at anyrate, the continual soaking of their garden border, which should, of course, contain a large proportion of peat. For the geological agency of bog-plants, see PEAT.