Dear M^r Darwin

I have been looking with Prof. Oliver at the specimens of the Saharunpore Hibiscus.¹ Assuming that the facts are as they have been stated it is a very striking case indeed. Hibiscus tricuspis is indigenous in the Pacific Islands whence according to Roxburgh it was introduced into India.² There it produces a sport according to M^r Bell and D^r King which appears to Prof. Oliver and myself identical with the Hibiscus tiliaceus which is indigenous in India.³

Now it is an empirical fact which has come out in the sorting of large collections of plants in the Kew Herbarium that the foliage of plants growing in islands has a tendency to be heteromorphic—that is to say plants with entire leaves are apt to produce divided leaves. This is especially the case with the collections recently made at Rodriguez.⁴ According to D^r Hooker⁵ it is also true for New Zealand. It is difficult to see any reason, but the fact seems to rest on a sufficient basis.