286 Transactions. — Botany. 



This variation chiefly concerns form of leaf, imbricating of 

 leaves or the contrary, and length of internodes. Amongst a 

 number of plants of which an exact measurement of leaf, &c, 

 was taken by me the largest leaf measured 14-5 mm. x 5 mm. 

 and the smallest 6 mm. x 4 mm., a difference of 8-5 mm. in 

 length and of only 1 mm. in breadth. The proportion of 

 length to width varied considerably in other cases ; for in- 

 stance, 2 : 1, 3 : 2, 3 : 1, and 5 : 3, &c. The longest internode 

 was 4-75 mm. and the shortest 1-5 mm. Of sixteen plants 

 examined, five had imbricating leaves and eleven had patent 

 leaves, wmile only two had leaves of the same size and none 

 had internodes of the same length. The leaves also varied 

 very much in the degree of concavity of the upper surface or 

 the degree of rounding or drawing out of the apical end. 

 From the above it can be seen how great the variation is 

 amongst individuals of V. odora. How far these individuals 

 reproduce themselves " true " from seed, or, if they vary, how 

 great is the proportion of variation in a certain direction, such 

 as in the important cecological difference of patent or imbri- 

 cating leaves, is a matter of considerable interest, and requires 

 much careful and patient work. V. traversii, as I pointed 

 out before, * does not individually produce itself "true" from 

 seed, and the like is to be expected in all these variable 

 Veronicas. 



The seedling leaf-form of V. odora consists of, first, a very 

 early appearing entire ciliated leaf, and, second, of a leaf more 

 or less deeply toothed and ciliated. The first form much 

 resembles that of V. traversii and some other Veronicas, but 

 whether it be an approximation to the ancestral leaf-form of 

 a certain section of Veronica cannot, with our present know- 

 ledge of seedling forms of this genus in New T Zealand, be 

 determined. The adult form of leaf is evidently an adapta- 

 tion to its environment, the cold wet station of the plant 

 being most likely physiologically dry. Cultivated plants grow 

 in my garden in stations so dry as a sand-dune ; one particular 

 plant has occupied such a position now for eight years, and 

 has received no artificial water-supply. The seedling leaves, 

 on the other hand, are adapted for moister conditions. In 

 the shade-house a plant from Mount Torlesse has produced 

 for the past two years toothed ciliated leaves resembling a 

 2nd seedling leal', while a few of the youngest leaves have 

 at present entire ciliated leaves similar to the 1st seedling. 

 A species with such capabilities for adaptation to a wet 

 or a dry climate should easily conquer in the struggle for 

 existence a closely allied species without such adaptive capa- 

 bilities. 



* I.e., p. 377. 



