Wall. — Distribution of Senecio saxifragoides Hook. f. 205 



found growing among tussock and occasionally on northerly faces, and both 

 descend nearly to sea-level in situations hacked by high hills, but appa- 

 rently not otherwise. It may be conjectured that both were far more 

 widely distributed (within the limits here described) before the advent of 

 white men, for where the ground has been permanently fenced and pro- 

 tected from stock S. lagopus, in particular, grows freely at a distance from 

 rocks, especially on steep slopes and those facing south and south-west (as 

 on the old Summit Track, where it rises to the ascent of Mount Sinclair 

 on the south side, and where it runs along the southerly flank of Mount 

 Herbert). Both also are found to grow among grass, &c, at the foot of 

 cliffs and crags ; but here, being accessible to stock, they live but pre- 

 cariously, and cannot form the large masses in which they cluster upon the 

 rocks themselves. Thus both species, while now almost purely rupestral in 

 their habit, were probably present in quantities over a very large area 

 where they can now obtain no foothold. 



4. Conclusions.* 



1. Cockayne's surmise in regard to the restriction of the habitat of 

 S. saxifragoides is proved to be absolutely correct, though it is possible that 

 the plants of the Mount Herbert district are intermediate, or even hybrid 

 forms. 



2. The " bristles " of Hooker's, Raoul's, and subsequent descriptions are 

 simply glandular hairs, and both species bear them, though in varying 

 quantity and differently distributed upon the leaf in the two cases. 



3. Both species, in common with S. bellidioid.es and S. Haastii, have 

 typical hydathodes at the ends of the veins, and both bear purple glandular 

 hairs which are not mentioned in previous descriptions. 



4. Neither species has the glandular hair or " bristle " as a distinctive 

 character. The two species differ from one another only in respect of the 

 frequency and locality of occurrence of both glandular hairs (" bristles ") 

 and silky hairs. Those differences in degree, being certainly hereditary, 

 constitute true unit characters. The two kinds of hairs are thus unit 

 characters common to the two species, but the abundance or sparseness of 

 such hairs is a unit character peculiar to either species, as the case may 

 be, and their sole distinction. 



5. As the two groups of individuals keep their individuality, each in its 

 isolated, fairly wide area, they are almost certainly microspecies, and they 

 should be grouped together as an aggregate, with saxifragoides as the name 

 of one group and some other name for the lagopus group. It would seem 

 advisable that S. bellidioides, S. Haastii, and S. southlandicus should also 

 be brought into this aggregate, since they have in common with them the 

 woolly rootstock, marginal hydathodes, and glandular hairs upon the sur- 

 face and the margin of the leaf. 



6. Such varieties as the two under consideration, which have every dis- 

 tinguishing character in common, and which differ only in the hereditary 

 degree of intensity, or the distribution of such characters, form a class of 

 varieties (microspecies) different from those which are usually considered 

 such through their possession of one or more quite distinct characters. 



7. The question whether the remarkable variation of S. saxifragoides 

 can be explained at all is only approached here with extreme caution and 



* Regarding these conclusions I have consulted Dr. Cockayne, and they owe their 

 present form to his suggestions. 



