180 Transactions. 



be seen in the multiplicity of forms assumed by M. Ralphii and connecting 

 M. bullata and M. obcordata. Thus, to those believing that " intermediates " 

 obliterate the distinctions between groups which if not so connected would 

 be species, the only logical course to take would be either to unite all three 

 species of Myrtus under the earliest name, ' l bullata" or to uphold M. bullata 

 and M. obcordata, which form the unlike poles of the series, and to treat 

 the intermediates — i.e., M. Ralphii — as unnamed varieties of whichever 

 of the two species they most resembled. For action of this kind the New 

 Zealand and many other floras offer ample precedent ; indeed, one or other 

 of the methods suggested above would be the orthodox taxonomic course 

 to pursue. All the same, the most inveterate " lumper " could not bring 

 himself to unite groups so absolutely different as those represented by 

 M. bullata and M . obcordata. 



Some exact details regarding the polymorphy of Myrtus Ralphii may 

 here be given in support of my contention that it is of unfixed hybrid origin. 



On and near the saddle joining the Kaukau Range and Mount Crowsnest, 

 near Wellington City, there is a remarkable scrub-association which owes 

 its presence to excess of wind. In certain places near its outskirts there 

 is abundance of the three species of Myrtus mentioned above growing side 

 by side. Although frequently somewhat stunted in habit, M. bullata can 

 be recognized at a glance ; so too, generally, with the individuals of M . 

 obcordata. But on examining the bushes of M. Ralphii it is seen at once 

 that there is no uniformity amongst the individuals, some coming some- 

 what near to M. bullata in colour, shape, and blistering of leaf, while others 

 are far more of the obcordata type — some, indeed, being almost identical with 

 that species. Thus a hybrid origin is at once suggested, and close examina- 

 tion for and against such a supposition demanded. 



Happily for such an investigation, Myrtus bullata and M. obcordata 

 possess certain well-marked distinguishing characters. Thus, taking the 

 leaves alone, even were the flowers of the two species identical, so different 

 are the leaves that no taxonomist would unite the species. For bullata 

 there is (1) the large leaf, (2) its bullate surface, (3) its usually acute apex, 



(4) its power of becoming reddish-brown when exposed to the sun, and 



(5) the base of the lamina not narrowed into the petiole. True, the bullate 

 surface may be strongly flattened in a plant grown in complete shade, but 

 it is always present more or less and is a marked unit-character. Then, 

 for obcordata there is (1) the small leaf, (2) the rounded emarginate apex, 

 (3) the flat surface, (4) the tapering base of the lamina, and (5) the more 

 feeble response to coloration by intense light. 



A number of specimens were collected of the three " species " of myrtle 

 growing side by side on the outskirts of the wind-swept scrub, each speci- 

 men being taken from one individual. Of these, after examination, some 

 were put on one side as true Myrtus bullata, others as true M. obcordata, 

 and twenty-two were considered to be M . Ralphii. 



A closer examination of these twenty-two showed that the specimens 

 fell into two classes — the one with large brownish-red, more or less bullate 

 leaves, and the other with much smaller, greener, and flatter leaves. But 

 these differences affected only the bulk of the leaves of each specimen. From 

 even the largest-leaved specimens with leaves of bullata type small leaves 

 of obcordata type were picked. Any of the fundamental characters mentioned 

 above might be present, absent, or even combined. The twenty-two 

 M. Ralphii specimens were each numbered and examined in detail. Here 

 arc a few results : — 



