Next follow a few composite flowers (order _Compositæ_), the first of which is the Marsh Thistle (_Carduus palustris_) that varies from two to eight feet in height, and bears dense clusters of purple (occasionally white) heads during July and August. Its stem is stiff, hollow, slightly branched, and thickly covered with very prickly wings that are continuous with the margins of leaves above them. The leaves are narrow, wavy, deeply divided into prickly lobes, with scattered hairs on both surfaces; the lower ones often seven or eight inches long; and the upper much smaller and narrower. The flower-heads are ovoid, surrounded by an involucre of many closely-overlapping bracts with prickly tips. The two Bur Marigolds (_Bidens_) are more or less common in marshes and other wet places. They are both smooth plants with opposite leaves, and hemispherical heads of yellowish flowers surrounded by two or three rows of bracts, the outer of which are spreading. The receptacle is flat, with membranous scales between the florets; and the fruits are crowned by from two to five stiff, prickly bristles. The more abundant of these is the Nodding Bur Marigold (_B. cernua_), a stout plant, from one to two feet high, distinguished by its narrow, entire, sessile leaves, and its drooping flower-heads. The other--the Trifid Bur Marigold (_B. tripartita_)--has three-cleft, stalked leaves, and heads erect or only slightly drooping. [Illustration: THE BROOKLIME.] The Common Ragwort of waste places, described on p. 187, is represented in marshes and wet places by a very similar plant called the Marsh Ragwort (_Senecio aquaticus_), which varies from one to three feet in height, and flowers in July and August. Its stem is more slender than that of _S. Jacobæa_, and is usually more branched. The leaves are either deeply toothed, or pinnately cut into segments which decrease in size towards the base. The yellow flower-heads are not so densely crowded as in the Common Ragwort, and have longer stalks. The _Scrophulariaceæ_ contains three common plants of the _Veronica_ genus that grow in wet places. All three are similar in that they have opposite leaves; a corolla with a short tube, and four spreading limbs, of which the lowest is narrowest; two stamens; and a capsular fruit, flattened at right angles to its partition, opening by two valves, and containing a few seeds. One of these is the Marsh Speedwell (_Veronica scutellata_), abundant in the marshes and ditches of most parts of Britain. It has a weak, straggling stem, from four to eight inches high, with creeping runners at the base; narrow, smooth, sessile leaves, either uncut or only slightly toothed; and slender racemes of pale pink or white flowers on axillary peduncles arranged alternately, there being only one raceme at each node.