The _Gentianaceæ_ is represented in bogs by the common Buckbean or Marsh Trefoil (_Menyanthes trifoliata_), the only member of its family with trifoliate leaves. This plant has a creeping stock; and its flowers, which are pink in the bud and pinkish white when expanded, are in handsome racemes on stalks from six inches to a foot in length. The calyx has five short lobes; and the bell-shaped, fleshly corolla is deeply cut into five lobes which are beautifully fringed above with delicate filaments. The time of flowering is May to July. [Illustration: THE MARSH TREFOIL.] [Illustration: THE MARSH LOUSEWORT.] In the marshes, ditches, and wet meadows of most parts we may see the Red Rattle or Marsh Lousewort (_Pedicularis palustris_) which belongs to the order _Scrophulariaceæ_. It has an erect stem, from six to eighteen inches high, with reddish branches; and pinnate leaves with many oval segments more or less deeply cut. Its rather large crimson flowers are on very short stalks in the axils of the upper leaves, forming together a leafy raceme. The calyx is a broad, hairy tube, with two irregularly-toothed lips; and the corolla is much longer than the calyx, with two lips, the upper of which has four minute teeth. After flowering the calyx becomes much swollen; and the superior ovary ripens into a capsule with a few rather large seeds. This plant flowers from May to September. Most wet places are characterised by the presence of one or more species of Willows--those water-loving trees and shrubs which constitute the genus _Salix_ of the order _Salicaceæ_. Some of them almost invariably establish themselves along the banks of rivers and streams, and may often be seen in long tortuous lines which mark the positions and courses of streams that no longer exist; while others thrive best in the standing water and sodden soils of marshes and bogs. One species in particular, the Osier, is largely cultivated for its long, slender twigs, so useful in the manufacture of baskets and other wicker-work; but two or three others are valued for the same purpose, and are either specially cultivated, or pollarded with the object of securing suitable twigs for this work. [Illustration: THE YELLOW FLAG.] Nearly all the species have very narrow leaves, with prominent stipules at the base; and their flowers grow in erect or horizontal catkins with undivided scales. The flowers are always unisexual, the male and female blossoms being produced on separate trees. The former have from two to five stamens; and the latter a one-celled ovary that ripens to a capsule containing many seeds, each with a tuft of silky hairs. A few of these trees are common in marshes and bogs, but they are so similar in their general features that the identification of species is somewhat difficult for a beginner.