The Smooth Hawk's-beard (_Crepis virens_) has a furrowed, branched stem, from a few inches to three feet in height. Its spreading radical leaves are deeply toothed, and narrower towards the base; and the stem leaves are narrow and sagittate. The numerous small heads of yellow flowers are panicled, and the outer florets are often tinged with red. The heads are surrounded by two rows of bracts, the outer of which are shorter and narrower, and the whole involucre assumes a conical form after flowering. The fruit is shorter than the pappus; tapering, but not beaked; and the pappus consists of several rows of unbranched, silky hairs. This plant flowers during July and August. It is very common on waste land, and may be frequently seen growing on old walls, and even on the roofs of country cottages and out-houses. [Illustration: THE SHARP-FRINGED SOW-THISTLE.] The genus _Hieracium_ (Hawkweeds) is a puzzle not only to the beginner, but also to experienced botanists, who have not yet agreed as to its division into species. According to some authorities these latter amount to seven, but they, or rather some of them, are so variable, and present so many intermediate characters, that some botanists divide the British members into no less than thirty-three species. All the plants of the group agree in the following particulars:--They have a milky sap. The leaves are nearly all radical. The flower-heads are either yellow or orange, surrounded by several rows of overlapping bracts. The receptacle is pitted. The fruit is not beaked, and its pappus consists of a single row of rigid, brittle, brownish hairs, which are simple and of unequal lengths. One species at least is a common wayside flower, and this is the Shrubby Hawkweed (_H. boreale_). It grows from two to four feet high, and bears a corymb of many yellow heads, from July to September. Its stem is hairy below, downy with fine branched hairs above, and bears rigid, erect branches which are leafy, and often of a reddish colour. This species has no radical leaves. The stem leaves are ovate or lanceolate and toothed, the upper ones broad and slightly clasping the stem. The peduncle is scaly or woolly, and the involucre bracts are of a blackish green colour. [Illustration: THE SMOOTH HAWK'S-BEARD.]