METAMORPHOSES OF INFLORESCENCES AND FLOWERS. 95 



peduncle and pedicels elongate, becoming pink or purplish, and assume 

 a large feather-like structure. Of course all functions of a reproductive 

 character are entirely gone. 



Fasciation is another common affection among peduncles, but it does 

 not reveal any special use to the plant. The flowers, however, remain # 

 perfect, perhaps sometimes increased in number, and their fruits are 

 fertile.* 



Bracts and Bracteoles. 



Origin of Bracts. — Bracts and their diminutives, bracteoles, are usu- 

 ally abortive or arrested leaves, from the axils of which peduncles, 

 pedicels, and sessile flowers arise. In their origin, they may be homo- 

 logous with the petiole, or leaf-stalk, alone, or with the lamina, or blade, 

 alone. As an example of the former, perfect transitions can be found 

 between the "pedate" leaf- of the Hellebore and the small oval and 

 pointed bract. This is obtained by reducing the blade to nothing and 

 expanding the petiole. 



In Buttercups, however, the bract will be seen to consist of rudi- 

 mentary segments of the lobed blade, the petiole being suppressed. 



In some flowers, as the "Willowherbs (Epilobium), the bracts are 

 normally sessile leaves merely reduced in size. 



Useful Changes. — Though bracts are usually rudimentary leaves, they 

 constitute useful bud-scales, and so protect the flowers or florets within 

 them. Thus in Composites they form the "involucre," i.e. a "wrapper," 

 but they may retain or re-acquire a foliaceous character. They can thus 

 perform all the assimilative and other functions of leaves. Such is the 

 case with the large " spathe " of most Aroids, as of our Arum maculatum, 

 the " Lords and Ladies." 



Another use to which they are sometimes put by Nature is to make 

 them attractive by their being white or brightly coloured. Thus 

 in " Everlastings," among Composites, they may be white, yellow, red, 

 purple, &c, while the florets themselves are comparatively inconspicuous. 

 In Hedaroma (Darivinia) and Hcemanthus, the bracts take on a very 

 bright coloration and assume all the appearances of a gorgeous corolla. 



In some species of Cornus the four bracts are white, so that the head 

 of flowers mimics a four-sepaled Clematis. 



Useless Changes — Several members of the Compositce growing in dry 

 inhospitable conditions develop spines in place of the bracts of the 

 involucre. This spinescence is a common feature in other organs on desert 

 plants as the result of drought. Such occurs in Thistles, and especially 

 Centaur ea Calcitrapa, the 'Caltrop,' so called from the resemblance of a 

 head to that instrument of warfare. Such is not, however (any more 

 than spiny shoots and leaves of Thistles and Gorse), intended for a pro- 

 tection against browsing animals, but is simply a common result of a 

 deficiency of water. 



In many plants bracts and bracteoles are quite rudimentary and 

 useless, as in Umbelliferce, or wanting altogether, as in Crucifene. 



* For further details on this subject, I would refer the reader to my paper ou 

 Fasciation and Allied Phenomena," Journ. R.H.S. vol. xxvi. p. 155. 



