From J. D. Hooker   [26 December 1858]¹

My dear Darwin

I wish we could have a little work together— When shall we ever get to a reasonable agreement?.— I am horrified to find that you think Australian forms lower than Old World ones; because under every method of determining high & low in Botany the Australian vegetation is the highest in the world—²

• 1. The proportion of Phænog. to Cryptog is infinitely greater in Australia than elsewhere. (this as being a mere condition of climate I do not give much for)
• 2. Monocot to Dicot. are in same proportion as elsewhere.
• 3. Petaloid (& higher Monocot) are in greater ratio to Glumaceous in Australia than in Europe.
• 4 The 4 orders of Dicots considered by different systematists as highest are Compositæ, Myrtaceæ, Leguminosæ & The Ranunculaceous including Dilleniaceæ &c.— Now I believe (I have not tabulated yet)—that all these are in greater proportion & more varied & peculiar in Australia than in any other country.
• 5 Then granting with heretical JH that Conifers are highest. Phænogs—& they are as numerous & most varied.³
• 6. There are very few Monochlamydæous or Achlamydeous Dicots. in Australia.

Now I have been using your line of argument to my own purposes, in this fashion.

“Granting with Darwin, that the principle of selection tends to extermination of low forms & multiplication of high; it is easy to account for the general high developement & peculiarity of Australian forms of plants—these being the remnants of an extensive Flora of great antiquity & which covered a very extensive now destroyed Southern continent &c &c &c How often do I say all our arguments are edged swords—

Again—some Australian plants are rapidly running wild in India as Casuarina, & I believe several Acacias in Nilgherries & some other Leguminosæ.

We cannot argue any thing by contrasting the multiplication of European forms in Australia & New Zealand with the absence of the converse in England— our Spring-frosts account for the difference. In South Europe I believe various Australian forms are rapidly being naturalized. Consider too the current of export of European agricultural notions & plants to Australia & consequent alteration of conditions & that nothing of that kind comes back to Europe.

Your letter has interested me more than any you ever wrote me (because we are both ripening I hope) but it staggers me too.— It opens a much wider question upon which I have often pondered in vain—& have hoped latterly to have made more of— it is this—are we right in assuming that the developement of plants has been parallel to that of animals. I sent out a feeler in the concluding notices of my Review of ADC. where I indicate my views that Geology gives no evidence of a progression in plants.⁴ I do not say that this is proof of there never having been progression—that is quite a different matter—but the fact that there is less structural difference between the recognizable representatives of Coniferæ, Cycadeæ, Lycopodiaceæ &c &c & Dicots of Chalk & those of present day, than between the animals of those periods & their living representatives, appears to me a very remarkable fact & one that must enter into all our