232 BRITISH FLOWERING PLANTS chap. 



female florets, in which the tubular corolla terminates on 

 the outer side in a white leaf or ray, which is useful in 

 making the flower conspicuous. The inner florets are 

 also tubular, but are small, yellow, and without a ray. 

 Each of these florets has stamens as well as a pistil. 

 The anthers are united at their sides so as to form a 

 closed tube, within which the pistil lies. They ripen 

 before the pistil, and open on their inner sides, so that 

 the pollen is discharged into the upper end of the tube 

 above the head of the pistil. When the flower opens 

 the pollen is already ripe, and flUs the upper part of the 

 stamen tube. A floret in this condition is represented 

 in Fig. 150. The style, however, continues to elongate, 

 and at length pushes the pollen against the upper end 

 of the tube, which gives way, and thus the pollen is 

 forced out of the tube, as shown in Fig. 151. The style 

 itself terminates in two branches, which at first are 

 pressed closely to one another, and each of which termi- 

 nates in a brush of hairs (Fig. 152). As the style elon- 

 gates, this brush of hairs sweeps the pollen cleanly out 

 of the tube, and it is then removed by insects. When 

 the pistil has attained its full length, the two branches 

 open and curve downwards, so as to expose the stig- 

 matic surfaces (Fig. 152, st) which had previously been 

 pressed closely to one another, and thus protected from 

 the action of the pollen. From this arrangement it is 

 obvious that any insect alighting on the flower-head 

 would dust its under side with the pollen of the younger 

 flowers, which then could not fail to be brought into 

 contact with the stigmatic surfaces of the older ones. 

 As the expansion of the flowers begins at the outside, 

 and thence extends to the centre, it is plain that the 

 pollen of any given floret cannot be used to fertilise one 

 situated on its inner side. Consequently, if the outer 

 row of florets produced pollen, it would in the great 

 majority of cases be wasted. I have, however, already 

 mentioned that these florets do not produce pollen, 

 while the saving thus effected enables them to produce 

 a larger corolla. It is also interesting to observe that 



