l62 



DICOTYLEDONS 



underground by the contraction of the roots, and consequently 

 the leaves are, in each year, pressed close to the surface of 

 the soil. Inflorescence (fig. 253). — The part which is popularly 

 spoken of as the " Dandelion-flower " is an inflorescence, and 

 consists of many (100 to 200) flowers inserted close together on 



a dilated terminal part 

 of the stem. This state- 

 ment is easily proved 

 by pulling out one of 

 the flowers from the 

 capitulum, and seeing 

 that it consists of suc- 

 cessive whorls of floral 

 leaves. The inflor- 

 escence-axis bears, im- 

 mediately beneath the 

 insertion of the flowers, 

 a number of bracts 

 forming an involucre, 

 which surrounds the 

 collection of flowers. 

 The dilated terminal 

 part of the inflor- 

 escence-axis is often 

 termed the " recep- 

 tacle " ; but it must be 

 remembered that this 

 has no connection with 

 the receptacle of a 

 single flower. Within 

 the general involucre 

 the central bracts have 

 been suppressed; and 

 only the outermost 

 series of flowers stand 

 in the axils of bracts 

 which form the green 

 involucre. The capitulum (figs. 253, 254) of the Dande- 

 Uon displays movements. It closes in the evening or in 

 dull weather, and opens in the morning or in sunlight. In 

 addition, the inflorescence-axis executes certain movements 



Fig. 202. — Flower of Dandelion. Left-hand figure 

 is a complete flower : right-hand figure is a vertical 

 section. 



