THE EVOLUTION OF THE FLOWER 



1043 



origin of both sepals 

 and petals is to be 

 seen in the flower of 

 the Summer Snow- 

 flake {Leucojitm cesti- 

 vum). Each portion 

 of the perianth is 

 tipped ^^'ith a dot of 

 pure green, and this 

 spot stands up in 

 vavid contrast to the 

 snowy whiteness of 

 the organ. For what 

 special purpose this 

 conspicuous marking 

 of green may have 

 been retained it is not 

 eas\' to say ; it is all- 

 sufficient to indicate 

 to the student the 

 leaf ancestry of the 

 sepals and petals. 



A singular example 

 of a plant belonging 

 to an advanced family 

 which has not found 

 it necessary to pro- 

 duce any coloured 

 sepals or petals for 

 its flowers at all is to 

 be seen in the Green 

 Rose [Rosa viridis). 

 As the name of the 

 plant suggests, it is 

 entirely without any 

 tinted blooms, all 

 parts of the flower 

 being in the form of 

 small green processes. 

 If examined closely 

 the organs are seen to 

 be nothing more than diminutive leaves, 

 and these even go so far as to retain 

 the toothed edges which are such familiar 

 features of rose foliage. 



The change of the leaf into a tinted sepal 

 or petal is not, after all, such a very re- 

 markable happening, for coloured leaf- 

 like organs which exhibit their character 

 in all respects save that they are not green, 

 are not uncommon. One of the most 

 striking plants exhibiting this change of 

 colour in the leaf is the Bongainvillea 

 glabra, examples of which are to be seen 

 fairly often in greenhouses. The real 

 bloom of the Bongainvillea is insignificant. 



LEAF-LIKE SEPALS OF TULIP. 



nothing like so striking in appearance as 

 our Cowslip. They are developed in 

 clusters of three, and being of a pale 

 yellow, would scarcely be noticed amongst 

 the foliage were it not that each group 

 is enveloped by three conspicuous bracts. 

 These bracts are closely on the lines of 

 leaves, but are tinted in a highly attrac- 

 tive shade of Ulac. As has been indicated 

 in an earUer article, the Bougainvilloa is 

 well able to attract the attentions of 

 insects by means of its showy a]i})endages. 

 A more famiUar case of e.xtra floral colora- 

 tion is that to be seen in the Salvia Itor- 

 minimi rubra, a common garden species. 



