9 



3, Isogenous, when they ai'e present on both surfaees, but approximately equal 



in number above and below. " This almost equal distillation of the stomata 



coincides with the similarity of the colour of botli sides of the leaves." 



This method cannot, however, be used for diagnostic purposes with any degree 



of certainty, because of the variation in the distribution of stomata even in the same 



tree. 



Galls. — A-t one time I inclined to the opinion that the shapes of the leaf-galls 

 in Eucalyptus would be a useful character for classification. Mr. W. W. Froggatt, 

 who has of late years been giving special attention to Brachyscelidtc, finds that the 

 same insect frequents so aiany species that no general grouping of the trees based 

 on their galls can be made. 



Inflorescence. — Professor Tate points out that the usual form of inflor- 

 escence is an umbel which, by lengthening of the axis, passes to the panicle or 

 corymb. The transition from one to the other is so easy, he goes on to remark, and 

 often exemplified in the same tree, that it is obvious the form of the inflorescence is 

 not reliable as a specific character. Bentham liad previously drawn attention to the 

 unsatisfactory character of the arrangement of the inflorescence from the point of 

 view of the systematist. Naudin's grouping (second memoir) of fifty-six species (or 

 reputed species) known to him as growing in the gardens of Provence, is mainly 

 based on the inflorescence, but also depends on the fruits and leaves. It doubtless 

 was of local value, but it is based on characters which present so much variation as 

 to preclude its general application. 



Following is an abstract in Gardeners' Chronicle, 7th February, 1891 :— 



Section I. — Injlorescence in cymes or axillary umbels. 

 Capsules longer than the calyx tube. 

 Capsules shorter than the calyx tube. 

 («) Cymes 3-flowered. 



Leaves uniform, ojiposite. 

 Leaves uniform, alternate. 

 Leaves of two shapes. 

 (b) Cymes of 3 to 7 or more flowered. 

 Cymes 7-flowored. 



Leaves uniform opposite. 

 Leaves of two shapes, opposite at first. 

 Leaves uniform, always alternate. 

 {c) Cymes or uinbels, axillary, more than 7-flowered. 

 Leaves uniform. 



Leaves of two sliapes. * 



Section II. — Floirers in terminal panicles or corymbs. 



Flowers. — Witli reference to individual flowers, there is much variation in tlic 

 number of flowers in an umbel, and, to a less extent, in the colour of their filaments. 

 The colour in the vast majority of species is white or cream, but in a fcAV species, 

 e.g., leuco.vylon, sidero.vylon, r/tininalis, ficifolio, calophylla, pyriformis, it may be 



