Darwin Correspondence Project

12 April '56

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The Flora of Porto Sto may be stated at from 270 to 280 species (indigs and perfectly naturalized).

1. Of these, 7 or 8 are certainly, and one or 2 others doubtfully endemic—the doubt arising from difficulty of ascertaining identity of species— 3 or 4 of the 7 or 8 are sufficiently striking and abundantly growing plants. 2 or 3 represent Madn endemic sp: 2 or 3 are more of the nature of “weeds”.
2. Of plants common to Po So & Mad: but not hitherto found elsewhere, there are 20 or 21, perfectly certain, and 3 others doubtful.
3. Again, of plants common to Po So and other countries (mainland) of Europe, but not found at all in Mada there are 25 certain & 4 doubtful.
4. Lastly, of plants common to Po So and other countries (mainland) of Europe, but very rare in Mada there are 6, to which may perhaps be added 2, which are indeed only at this day occasional garden plants in Mada, whence they were introduced in 1834, into Po So which they have now completely overspread! One of these is a Tamarix, (T. orientalis L.?); and the other is the Hottentot Fig, (Mesembryanthemum edule L.)

Of classes 3 & 4, almost all are common European “weeds”, proving of course little any way. And let me add, that the very peculiar nature of the soil & climate of Po So as compared with Mada accounts of itself in great measure for the very different character & aspect generally of the vegetation in the 2 Islands. Many plants common in one Island, can not be made by any efforts to grow in the other.

This may be useful as a caution against attributing too much in this particular case to other possible modifying general causes or influences.

Hooker has I think considerably underrated the number of good endemic species in Madeira, which exclusive entirely of Po Stan & Deztan plants will be found I think rather to exceed than fall short of 100. But it would take a good deal more time & research than I can just now afford to speak positively & with accuracy on this head.

There are very many common endemic species in Madeira not occurring in Po So

In the Dezertas there are 3 very remarkable endemic common plants, one forming a new genus of Umbelliferae; another a new genus of Gramineae; the 3d a new shrubby Chrysanthemum, representing C. pinnatifidum L. fil. of Mada.

There is no freshwater fish in Po So (as in Mada) but the Eel (Ang. latirostris Yarr.) I believe Wollaston & I caught one ourselves in a puddle last spring.