Ii 4 PRACTICAL BOTANY 



are nearest the centre or apex, while on passing towards the 

 periphery the size regularly increases. 



Put on a higher power, and study these organs in detail, 

 beginning at the centre. 



If the capitulum be young enough, there will be found, as in 

 the vegetative bud, a naked apical cone, with a rather flatter 

 form, but a similar arrangement of tissues to that there ob- 

 served. Passing from the centre, the external surface assumes 

 an undulating appearance owing to the formation of 



1. Bracteoles, or small leaves, which arise similarly to the 

 leaves as above observed (p. 49), by outgrowth of the epidermis 

 and subjacent tissue : as they grow older they curve towards 

 the centre. Note the formation of hairs of various types from 

 single cells of the epidermis, this being a good opportunity for 

 tracing their origin. 



2. The rudiments of flowers, which appear in the axils of 

 the bracteoles, i.e. on the side nearer the apex. These are 

 likewise produced from the epidermis and subjacent tissue ; 

 they are, morphologically speaking, axillary branches. 



The development of the latter into the complete flower must 

 be carefully studied, by comparison of those nearer the centre 

 with older flowers near the periphery of the capitulum, or on 

 capitula of various ages. It is obvious that flowers which have 

 been cut in median section will be best fitted for this study. 

 Note the following successive stages of development 



a. Form of papilla, conical. 



b. Apex becomes flattened. 



c. Periphery of the flattened apex rises into a whorl of five 

 small lobes ; these are the petals, which are in the mature 

 flower united as a gamopetalous corolla. 



d. Between the corolla and the now depressed apex rises a 

 fresh series or whorl of five lobes ; these are the young 

 stamens. 



About this stage may be seen externally, below the corolla, 

 a slight protuberance on each side of the flower (as seen in 

 section) : this is the first appearance of the calyx, which 

 consists in the mature flower of two scaly sepals. This order 

 of appearance of the floral whorl is not normal but is the rule 



