BOTANICAL SUBJECTS. 129 



therel)y proving that the angles between the teeth were only 

 dwarfed axilhi'. 



In the Bryophijllum, however, we have a fleshy pinnate leaf 

 proper, like those of other Crassnlacese. It cannot be maintained 

 in this case that it is a cladophyl, because there is no subtending 

 dwarf leaf proper. Nevertheless, the Bryophylluni leaf behaves 

 like the cladophyl of the Xylophylla and that of Ruscus 

 androgynus. It produces buds between its indentations. You 

 may call it leaf or cladophyl, as you choose. The venation of the 

 Ruscus cladophyl is parallel, like that of the leaves of other Liliacea;. 

 The two are one thing. 



Helwiiigia ritsci folia has flowers on the midrib of its leaves. 

 It belongs to a different order from that which includes Ruscus. 

 Its leaves have stipules. It would, therefore, come under Asa 

 Gray's definition of leaf proper, yet on its midrib it bears flowers 

 like the cladophyl of Ruscus I 



For the purpose of impressing the reader with the homology of 

 leaf and stem, I will show that the leaf of phi^nogams, in many- 

 cases, is, to all intents and purposes, a cladophyl. 



As an illustration, I take the Centaiirea Babylonica. It has 

 decurrent leaves, that is, a winged stem. In other words, two of 

 the wings run up the stem, and become the two sides of the leaf- 

 blade. Further up the stem the leaf is depauperized into a 

 midrib, which is just margined. 



To my mind, the wings on the stem indicate that it was 

 originally a cladophyl, like that of Delesseria coriifolia ; that in 

 spite of the myriads of transformations through which this plant 

 has gone through — from seaweed to Centaurea — its cladophyl 

 character has stuck to it, and, unlike many other plants, it has not 

 been able to shake off, either from its petiole or its stem, the traces 

 of its low origin, viz., tli(^ cladophyl of seaweeds. Call it leaf as 

 we may, the leaf of this Centaurea is essentially a cladoijhyl. Its 

 stem and leaf are to each other as stem and branch. These wings 

 are remnants of seaweed wings or margins. In my opinion, all 

 seaweed l^ranches occupy the morphological position of phyUodia, 

 and the axillary bud occu])ies the position of a branch of the 

 phyllodium. There are four wings to the stem of this Centaurea, 

 but they are not continuous throughout. Two fresh ones com- 

 mence at each node, and entl by becoming the leaf-blades or 

 margins of the next leaf. Curiously enough, the nuMrib of this 



A p. 1724. I 



