12 



BRITISH FLOWERING PLANTS 



but they are more usually arranged round the 

 stalk. 



When leaves stand at different elevations on 

 opposite sides of the stalk they are called alternate 

 (fig. 73) ; when they are arranged in pairs, at 

 the same elevation, opposite (fig. 74) ; and when 

 several are placed at the same height, verticillate 

 or whorled (fig. 75). 



Tendrils are regarded as slender branches, or 

 leaf-stalks, which assume a spiral form, and twine 

 round various objects for support (fig. 71). Thorns 

 are either the ends of twigs produced into a sharp 

 point, or similarly modified portions of leaves and 

 leaflets. Prickles are hard, erect portions of the 

 surface of the plant. Thus we find thorns on 

 the Hawthorn and Sloe, but prickles on the Rose, 

 Bramble, and Gooseberry. 



Hairs are outgrowths from the superficial cells 

 of the stem, leaf, or root. They are generally 

 tubular. Stiff hairs are called bristles or seta;. 

 When they form a cluster, as in Barley, etc., the 

 cluster is called a beard ; when they contain an 

 irritating fluid, as in Nettles, they are called stings ; 



and when they exude any peculiar secretion, they 

 are called glandular hairs. 



Flowers 



Flowers are structures preparatory to the forma- 

 tion of the seed, and in many cases are the most 

 conspicuous parts of the plant. 



A perfectly formed flower consists of the calyx, 

 which is generally green ; the corolla, which is 

 often brightly coloured ; the stamens ; and the 

 pistil. In imperfect flowers the calyx or corolla, 

 or both, may be wanting ; or they may be replaced 

 by a single cup, called the perianth. 



A perfect flower contains both stamens and 

 pistil. Such flowers are called hermaphrodite. 

 Other flowers are called monoecious, and in these 

 only the stamens are developed, in which case 

 they are male flowers ; or only the pistil, when 

 they are female flowers. 



In some plants the stamens are united with the 

 pistil ; others, as said above, have only stamens 

 (as wild Hop and male Hemp) ; and others, again, 

 only the pistil (cultivated Hop and female Hemp). 



