182 Transaction*. 



The distribution of M. Ralphii needs a few words. As Cheeseman has 

 pointed out, it is a local plant and occurs throughout the North Island, 

 Ahipara being the most northerly locality yet recorded. This is the only 

 locality in Mangonui County known to Carse (Trans. N.Z. Inst., vol. 43, 

 p. 210, 1911), but M. obcordata and M. bullata grow in the same locality, 

 which, like M. Ralphii, is according to Carse the only locality for the former. 

 Here is indeed a crucial case. M. bullata is common throughout Mangonui 

 County, according to Carse (a most trustworthy observer) ; M . obcordata is 

 only known at Ahipara, but this, too is the sole station for M. Ralphii ! 



Without going into further details, I think all must agree that a strong 

 case is made out for the hybrid origin of Myrtus Ralphii. How far all 

 the individuals are actually the Fl generation between M. bullata and 

 M. obcordata it is impossible to say, but the extreme polymorphy suggests 

 that F2 and perhaps other generations are present where individuals are 

 abundant. It is also interesting to see how certain characters may appear 

 unchanged (pure), how others are obvious mixtures, and how others are 

 suppressed ; but without actual breeding experiments no conclusions can 

 be drawn. 



Taxonomically the only change demanded if M. Ralphii be considered 

 a hybrid is to write the name thus : X M. Ralphii. 



Appendix. 



Since writing the above I have received from Mr. R. H. Rockel, M.A., 

 a representative collection of the myrtles growing in the forest at the 

 " Meeting of the Waters," near New Plymouth. Each specimen of the 

 sixty-one specimens sent was taken from a different individual, and so great 

 has been the care exercised by Mr. Rockel and a friend of his who assisted 

 in the work that probably nearly every form of the area in question is 

 represented. 



A casual glance at the collection shows that my former word " astonishing " 

 used with regard to the polymorphy of Myrtus Ralphii in that locality is 

 no exaggeration. A more detailed examination of the material shows every 

 gradation between typical Myrtus obcordata and typical M . bullata ; there 

 are, in fact, specimens which could be called " giant obcordata " and " dwarf 

 bullata^ There is also a series of specimens which match the figure (No. 94) 

 of M. Ralphii in Kirk's Forest Flora. Though, taken as a whole, the speci- 

 mens can be arbitrarily divided into a number of groups, the majority of 

 the specimens has each its special characteristics. The following call for 

 particular mention : — 



(1.) Leaves stained brown, slightly bullate, apex rounded usually but 



some with obtuse apex and one or two slightly emarginate, bases 



rounded or tapering; lamina generally large — e.g., 2-5 cm. by 



2-3 cm. 

 (2.) Leaves similar to those in No. 1 but very pale green in colour. 

 (3.) Leaves quite of obcordata type so far as size, base, and colour go, 



but none are obcordate. 

 (4.) Leaves similar to those of No. 3 but considerably larger, but one 



or two of the smallest leaves are true obcordata. 

 (5.) Leaves for the most part very deeply stained with purple, base 



much tapering, apex rounded or subacute, blistering considerable, 



lamina frequently about 1-9 cm. by 1-2 cm. 

 (6.) Many leaves almost rotund but all with emarginate apex, lamina 



averages about 11 mm. by 11 mm. 



