148 THE BOOK OF NATURE STUDY 



the construction of its flowers and of the way in which they are 

 suited to pollination by insects will prepare the student to under- 

 stand the pollination arrangements in other members of the 

 great family of plants to which the Dandelion belongs. 



Practically every floret produces a fruit. The heads bearing 

 the ripe fruits are familiar to all children as " clocks/' After 

 flowering the head closes up while the fruits are developing, but 

 when the latter are ripe the bracts are bent back and the fruits 

 stand on the convex upper end of the inflorescence. Each fruit 

 has come from a single little flower. The corolla and stamens 

 of this have withered and fallen off, and the ovary has enlarged 

 into the fruit itself. The short stem-like region, which intervened 

 between the ovary and the hairy pappus, has lengthened and 

 carried the latter up on a long stalk. The hairs of the pappus 

 are bent back, and stand at right angles to this stalk, forming a 

 parachute-like expansion. The fruits are very easily detached 

 from the head, and are carried by the wind with the help of the 

 expanded pappus. When they settle down in a crevice of the 

 soil they will tend to remain owing to the presence of small up- 

 wardly directed teeth on the surface of the upper part of the 

 ovary. 



The success of the Dandelion and of many of its relations, 

 such as the Groundsel and Thistles, depends largely on the 

 certainty of each flower producing a fruit, and on the excellent 

 adaptation these show for wind dispersal. 



THE TULIP. 



The many cultivated forms of the Tulip are for the most 

 part varieties of a wild species, Tulipa gesneriana, which was 

 introduced from the Levant. In Britain one species with yellow 

 flowers, Tulipa sylvestris, is found growing wild. Any of the 

 single varieties of cultivated Tulips will serve for study with the 

 help of the following description. The examination of the plant 

 may perhaps be best commenced at its flowering season in the 

 spring, when it will have the appearance represented in the figure 

 (Frontispiece), but its life-history should be carefully followed 

 through the year. A plant in flower will be found to consist of 



