WCP2943

[1]¹

THE FERNS,

WHITCOMBE,

GLOUCESTER.

11. vi. 09

Dear D^r Wallace,

I am afraid I cannot help you. My two great Flor African Flora are still unfinished and it ma will probably be years before they are. Even if I live to see it accomplished — and even then they would hardly supply the basis of a trustworthy estimate owing to the imperfect supply of material for the earlier volumes.

Sir Joseph Hooker² estimates the known flora of the Indian peninsula at 17000 spp. But this includes the Temperate Himalayan Flora[.]

In the ‘Index flora sinensis’³ which I had prepared at Kew, I estimate the known flora ^{of China} in the Preface at 12000 spp. But this is mostly temperate.

[2] Geographical Botany badly wants data. The difficulty is that the working up of material does not keep pace with its acquisition. I used to sigh over the vast stores in the Kew Herbarium which are dead as far as science is concerned. If I were a younger man, I would try to get some International cooperation in cataloguing the pl flowering plants of the world. It is really a scandal that progress is so slow.

I am sending your letter on to Kew where perhaps my successor L^t. Col^l. Prain⁴ might be able to give you and some rough estimates. It occurs to me that some approximation [3] to the figures you want might be obtained from the Index Kewensis,⁵ which roughly gives the geographical distribution. But the labour would be enormous.

I wonder if you have seen the Cambridge Memorial volume⁶ on Darwin.⁷ If so I should be curious to know your opinion of my essay on his Geographical Distribution work. I suppose, except yourself and Sir Joseph Hooker, I am about the only person who could have told the story. I felt great interest in doing it.

Casimir de Candolle,⁸ Geneva wrote to me that he had tabulated the data given in Bentham⁹ and Hooker’s Genera Plantarum.¹⁰ I tried to get the results out of him without success. [4] But he wrote me that they led to the conclusion: — ‘La vegetation est un phénomène surtout intertropical, dont nous ne voyons plus que restes affaiblés dans nos regions temperées’[.]

I am delighted to see you are full of interest and work[.]

Yours very sincerely | W. T. Thiselton-Dyer¹¹ [signature]