I 1 42 



A TEXTBOOK OF THEORETICAL BOTANY 



be so interpreted) in unisexual flowers. The male flowers of Menispermum 

 catmdetise provide a good example, the stamens arising in a cluster at the 

 top of a short naked stalk, almost like a male flower of Taxus. 



A structure resembling an anthophore but apparently of different nature 

 is that called by Velenovsky a pericladium. This is a sub-floral stalk found 

 in many Liliaceae, varying from very short in Convallaria to a length equal 

 to that of the pedicel in Asparagus. The junction of pericladium and pedicel 

 is marked by a constriction in all these cases. The nature of this structure 

 is revealed by Tritileia (Fig. 1118), in which genus the flowers of some 



Fig. 1 1 18. — Pericladia in flowers 

 of: A, Tritileia. B, Antheri- 

 ciim. {After Velenovsky.) 



species have no pericladium and a long gynophore, while in others there is a 

 long pericladium and no gynophore. It would appear from the investiga- 

 tion of flowers of the latter type that the pericladium consists of a gynophore 

 to which the bases of the other flower organs are adnate, that is to say they 

 have cohered and adhered around it, forming a compound organ. The 

 constriction below the pericladium is thus the true base of the flower. 



THE FLORAL ENVELOPE 



The demarcation between the vegetative, leaf-bearing axis and the 

 flower is not always sharp or clear, especially with terminal flowers. As we 

 have described in the early part of this chapter, there may be an assemblage 

 of bracts or hypsophylls, below the flower, showing a more or less gradual 

 transition between the foliage leaves below and the sepals above. The 

 sepals may form a direct continuation of this series of bracts, or in some 

 cases, there may be no distinguishable sepals and the series of bracts forms 

 the outer envelope of the flower. Even where there exists a definite morpho- 

 logical boundary between bracts and sepals, the bracts may form a group 

 with an evident, special relationship to the flower and constitute what is 

 called an involucre. As Troll has maintained, there is no fundamental 



