194 BOTANY FOR BEGINNERS CHAP. 



near the centre, and the oldest towards the edge. From the 

 centre to the edge all stages in the development of the floral 

 organs can be made out. If a section is .cut through a young 

 capitulum, and the section treated with potash solution for a 

 short time, and then mounted in glycerine and examined with 

 a high power the central flowers will show the corolla appear- 

 ing as five small lobes. In an older flower, just within the 

 corolla, five projections will be seen these are the stamens. 

 In a still older flower the centre of the stamens will be filled in 

 with two carpels, which form the pistil. 



Thus, in the Daisy the corolla appears first, then the stamens, 

 and last of all the pistil. In the Sunflower the corolla and 

 stamens appear as in the Daisy, then the calyx, and last of 

 all the pistil. In the large majority of plants the appearance 

 of the floral whorls is the same as in the Wallflower, but as we 

 have seen there are exceptions. 



EXPT. 173. From the raceme of the Wallflower cut off the young 

 buds from the apex and lay them in regular order, placing the oldest 

 at one end and the youngest at the other end. With a sharp knife or 

 razor cut the buds into halves transversely, beginning with the oldest. 

 Examine with a hand-lens. Note 



(i) The oldest bud shows the petals, stamens and pistil coiled up 

 inside the calyx, the parts being very distinct. 



(ii) The anthers show small openings. These are called the pollen 

 sacs. 



(iii) The pistil is two-celled, and within it the ovules can be seen. 



(iv) From the oldest onwards the parts are less distinct. 



(v) In the younger buds the pistil is the least distinct, then stamens 

 and corolla ; the calyx is the best developed of all the parts. 



(vi) This shows that the calyx is developed first and the pistil last. 



EXPT. 174. Collect a number of inflorescences of the Daisy or 

 Dandelion, and examine them with a hand-lens. Note 



(i) The shape of the inflorescence. It forms a cone which is irregular 

 in outline. 



(ii) The younger inflorescences show the central flowers just ap- 

 pearing. 



(iii) The largest and oldest flowers are near the edge of the inflor- 

 escence, and the younger and smaller flowers in the centre. 



(iv) This shows that the growing point cuts off floral leaves from the 

 outer part of the torus first and from near the apex last of all. 



The Structure and Functions of the Sepals. The 

 green sepals resemble the foliage leaves in structure and ap- 

 pearance. They are covered with an epidermis, which contains 



