THE LEAF. 



217 



deeply forked, as in the interesting case of the honey- 

 suckle (Lonicera Periclymenum) described by Cela- 

 kovsky. The same thing lias also occurred in L. 

 thibetica (PI. XX, a). The extra leaves so formed are 

 not always equal in size to the others ; this was the 

 case with the median leaf in a ternate whorl of a 

 hybrid woundwort (Stachys palnstris x 8. sylvatica) 

 found by Mr. Sprague. In such a case as this there 

 must have been an unequal bipartition of one of the 

 leaves. In the cornelian cherry (Cor it us Mas) near 

 the tip of one shoot of the final pair of mature 

 leaves, one of the leaves had become imperfectly 

 divided into three leaves, each of which was four or 

 five times the size of the corresponding undivided leaf 

 of the pair. The bifid character of the leaf, indicating 

 the first stage in the formation of two leaves from one, 

 is very common as an abnormality, especially in plants 

 with opposite-decussate leaf-arrangement. 



No instance of a plant bearing normally bifid leaves 

 appears to be knoAvn. The case of Boehweria hiloba is 

 only in appearance an instance of such a phenomenon ; 

 Klein points out that in reality one of the two 

 apparent apices is merely a lateral tooth which has 

 become enlarged so as to equal the terminal part of 

 the leaf in size. 



b. From Opposite- decussate to Scattered {Spiral). — 

 Displacement, of course, occurs when the whorled or 

 opposite arrangement becomes changed into the alter- 

 nate. An imperfect change of this sort has occurred 

 in Buddleia Hemsleyana (PI. XXII, fig. 2) at Kew ; 

 this plant has opposite-decussate phyllotaxis. In one 

 plant a branch exhibited the following variations at 

 the successive nodes in passing from below upwards : 

 (1) normal ; (2) normal ; (3) leaves slightly dis- 

 placed ; (4) normal ; (5, 6, and 7) sub-normal, but 

 congested together owing to suppression of the inter- 

 nodes, and the leaves of the pairs are not precisely 

 opposite ; (8) leaves displaced vertically about half an 

 inch, and not on opposite sides of the stem but rather 



