320 FtELD AND WOODLAND PLANTS 



always well supplied with moisture ; and, being usually surrounded 

 by a damp atmosphere, they lose but little water by evaporation, 

 and thus require no reserves within their leaves or stems. 



Our first species is the well-known Wallflower {Cheiranthus cheiri), 

 of the order Cruciferoe. It is a rather shrubby plant, frequent on 

 old walls and ruins, where it flowers during April and May. Though 

 too familiar to need any description, we may note that in the wild 

 state it varies from six to twelve inches high, and bears sweetly - 

 scented, yellow or orange flowers. The plant is not indigenous, but 

 has now become naturaUsed as a wild flower in most parts of Britain. 



The Wall Rocket [Dijjlotaxis tenuifolia or Brassica tenuifolia), 

 of the same order, is a very similar plant, growing in similar situa- 

 tions, but it does not commence to flower till the summer is 

 somewhat advanced. Its stem is leafy, branched, smooth, woody 

 towards the base, but more slender than that of the Wallflower ; 

 and its very variable leaves are generally three or fom- inches long, 

 deeply divided pinnately into narrow segments with irregularly- 

 toothed margins, and emit a rather unpleasant odour when rubbed. 

 The flowers are of a pale yellow colour, fragrant, about three-quarters 

 of an inch in diameter, in terminal racemes, with sepals more or less 

 spreading ; and the fruits are narrow, flattened siliquas, with 

 membranous valves, about an inch and a half long. The plant is to 

 be found principally in the southern counties of England, and 

 flowers from July to September or early October. 



On diy rocks, chiefly in the hilly and mountainous districts 

 of North and West Britain, we meet with the Vernal Sandwort 

 {Arenaria verna) of the order Caryophyllacece. This is a Uttle 

 tufted plant, only from two to four inches high, with branched stems 

 more or less decumbent at the base ; and small, sessile, opposite, 

 very narrow leaves, each with tkree veins. The starlike, white 

 flowers are about a third of an inch across, on slender stalks, and 

 grouped in terminal, loose, few-flowered cymes. They have five 

 pointed sepals, less than a quarter of an inch long, each with three 

 prominent veins ; five spreading petals, a little longer than the 

 sepals ; ten stamens ; and a superior ovary with three narrow 

 styles. The fruit is a short ovate capsule which opens, when ripe, 

 by three valves. 



One of the Geraniums — the Shining Crane's-bill {Geranium 

 lucidum) — is almost essentially a plant of walls and rocks. It is a 

 beautiful species, smooth and shining in all its parts, with a tendency 

 to turn red, Uke the Herb Robert ; and, as in other plants of its 



