From W. T. Thiselton-Dyer   29 January 1878

Dear M^r Darwin

I have not got to the end of all the points on which you are so good as to allow us to help you. But this will be a first contribution to their solution.

Sir Joseph Hooker will have shown you some specimens of Cyclamen which Prof. Oliver very kindly looked out from our Herbarium for your inspection.¹ The point they illustrate is very curious though not perhaps so interesting to you as you hoped might be the case.

The plant called “sowbread” is Cyclamen Europæum (see Enclosure A).² In all the species of the genus except C. persicum the peduncles after flowering coil spirally so as to bring down the capsule to the level of the soil.³ They behave like Vallisneria see plate in Botanic Garden.⁴ Grenier & Godron very exact people say (B) de manière à enfouir la capsule.⁵ But Miller and Clusius (A & C) describe the capsules and probably with accuracy as only lying (incumbent) on the ground.⁶

M^r Bentham remarked to me that he thought this was likely to be of advantage to the capsules in more gradually maturing their seeds and kindly pointed out to me some observations made by himself nearly fifty years ago in his Catalogue des Plantes indigènes des Pyrénées on Helianthemum procumbens which he believed to be a variety of H. Fumana

si la variété les (graines) conserve plus long temps, c’est probablement parce que les branches étant étendues sur la terre, les capsules séchent moins vite. p. 85⁷

He thinks that this is the probable origin of amphicarpic habits—a hint which may be worth consideration.⁸ Perhaps the accompanying note on Lathyrus setifolius may be useful.⁹

As to Arachis—I notice in your last book you speak of the peduncles drawing down the pods which I imagine must be an oversight. There is a fine plate of the plant in the Flora Brasiliensis and I notice that though the habit of the plant is decumbent the buried pods are produced from the lower two inches of the main stem so that it ought to be a matter of indifference whether the plant is trained on sticks or not.¹⁰

Next with respect to the names.

i The plant with a rosette of leaves “spiral” of which if I remember rightly the second example was dead is correctly named Echeveria pulverulenta, Nutt. and is from California. Baker having reduced Echeveria to Cotyledon it now becomes Cotyledon pulverulenta, Baker. It so happened, however, that another plant existed in gardens with the name Cotyledon pulverulenta. This was sent you & had decussate “opposite” leaves, the successive pairs crossing   It is a native of the Cape and the name being apparently only a garden name it is best described as an unnamed form near C. orbicularis. I enclose M^r Baker’s memorandum D¹¹

ii. The plant of which you so kindly gave me fruits is Araujia sericofera, Brot. The plant well known in gardens as Physianthus albens, Mart. appears to be the same species.¹²

iii. The Cactus is probably a garden hybrid. A plant in our Cactus house called Phyllocactus multiflorus seems to be identical. That name, however, seems to rest on no authority and if you are on that account dissatisfied with it you might call your plant a garden variety (of which there are many) of Cereus speciosissimus.¹³

iv. The Acacia with long narrow leaves = A. iteaphylla, Müll. This is a name with a little doubt attaching to it and M^r Bentham refers it to A. neriifolia, A. Cunn.¹⁴ The other Acacia “like A. cultriformis is A. buxifolia A. Cunn.

M^r Spencer Le Marchant Moore was so good as to determine these names.

v. The two ferns have been named by M^r Baker and to avoid confusion I enclose fragments in envelopes E & F¹⁵

It is a curious point as showing that “bloom” cannot have a very deep significance—that Polypodium aureum in its most general form is a virescent and not a glaucous species.¹⁶ The form with bloom has been seized upon by horticulturists as the most ornamental

vi. The “Lycopodium” is perhaps Selaginella Kraussii—but in a barren state they are difficult to determine with certainty.¹⁷

Returning to Cyclamen. You will notice some of Gay’s sketches of the Germination on the sheets brought by Sir Jos: Hooker.¹⁸ Also it will interest you to notice how excellent and keen an observer Clusius was.

Trattinick in his Archiv.¹⁹

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dichotomy in leaves is almost unknown in phanerogams. In some of the large compound-leaved Aroids however the ultimate divisions of the leaf have a distribution of veins like Saporta’s sketch and I send a fragment (enclosed) of a remarkable plant which we have from West Africa which, size apart, has some similarity to the sketch²⁰

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