2 2 2 DISTINCTION OF SPECIES. 



calidnitm y so common in spring upon stony soils, and the 

 Alyssum montanum, can only be distinguished from one 

 another by the fact that the calyx of the former is persistent, 

 of the latter caducous. It is true that the flowers of the 

 Alyssum calicinum are of a yellow which easily passes into 

 white, while those of the Alyssum montanum are of a beautiful 

 permanent yellow. But this latter distinction is not so good 

 as the former. 



The persistent calyx sometimes assumes a considerable 

 increase of very common appearance. For example, take 

 the Phy sails alkekengi, a member of the Nightshade family or 

 Solanacese. The red bladder-like accrescence surrounding 

 the scarlet fruit is the calyx, which, after flowering, has grown 

 much larger than it was before. And these bright flowers which 

 resemble large strawberries, and abound on the borders of 

 meadow-paths, if you look at them closely, you find to be 

 the accrescent calices of the Trifolium fragiferum. The very 

 word fragiferum reminds us of the strawberry. 



The calyx may change in consistency and texture in pro- 

 portion as the ovary, to which it adheres, changes into fruit. 

 The fleshy pulpy substance of the apple, and, in general, of 

 the fruits of the Pomacese, is simply an excessive develop- 

 ment of the calicinal tube united all around the ovary, and 

 recognisable in the pips, imprisoned, towards the centre, in 

 horny lobes. In other plants, as the flower develops into 

 fruit, the calyx becomes woody : such is the case with the 

 Water Chestnut (Trappa natans). 



Finally, the calyx may even contribute to the dissemination 



