THE LOWER DICOTYLEDONS. 323 



corollas. In Silene nutans the flower opens during three 

 successive nights, five stamens shedding their pollen on each 

 of the first two nights and the styles protruding on the third. 

 In the night-flowering Catchflies the petals remain curved 

 inwards during the daytime. 



334. Wallflower (Cheiranthus chelri) can be obtained 

 in flower at almost any time of year. Various other plants 

 of this easily recognised family should also be examined. 



Note the perennial erect stem, woody and cork-clad below, 

 green and five-angled above ; the crowded sessile lance-shaped 



LONG STAMEN STIGMA 



SHORT STAMEN 



NECTARY c:j 



Fig. 126. Vertical Section of Wallflower. 



leaves, entire or slightly toothed, arranged in five rows ; the 

 numerous branches, often ending in a bractless raceme of 

 flowers (rich red or purplish brown in garden plants, yellow 

 in the wild form which grows chiefly on old walls). The 

 younger parts, including the sepals (outer side) and the 

 ovary of the flower, bear curious hairs, not easily seen but 

 plainly felt on drawing a leaf (underside) across one's lips. 

 These hairs are pointed at each end and lie parallel with the 

 surface of the stem or leaf, attached by a short stalk at the 



