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Darwin Correspondence Project

From Alphonse de Candolle1   8 October 1877

Genève

8 oct. 1877

Mon cher Monsieur,

Je puis vous adresser quelques mots en addition à ma lettre du mois d’aout sur les plantes à matières glauques.2 C’est plutot à l’appui de mes doutes, que pour les dissiper, mais sur un point cependant je serai plus affirmatif.

Dans la dernière session de la Société helvétique des Sciences naturelles, à Bex, nous avions dans la Section de botanique Mr de Bary et Mr Planchon, outre plusieurs botanistes suisses.3 Un jeune Lucernois, Mr Schnyder, professeur de botanique à Buenos-Ayres, nous a lu un interessant mémoire sur la géographie physique et botanique de la république Argentine.4 Il distingue cinq régions très différentes, les unes très humides et d’autres très sèches. J’en ai pris l’occasion de parler de votre demande sur la proportion des plantes glaucescentes en diverses contrèes du globe. On a reconnu avec moi qu’il est impossible d’en donner les proportions, à cause des espèces grises qu’on décrit comme glauques et surtout des intermédiares entre les matières glauques très visibles et celles qui sont transparentes ou fort peu apparentes. On a cité des plantes glaucescentes (véritablement et fortement) dans les pays chauds et humides, comme les Musa, Strelitzia, Cannacées, etc, mais personne ne peut dire quelle proportion elles constituent des flores équatoriales. Sur ma demande expresse: si les plantes glauques ne sont pas nombreuses dans les pays desséchés; Mr Schnyder a confirmé mon opinion. Il les a vues frequentes dans les regions arides de la Plata, et cela dans une proportion qui parait notable pour des flores extrèmement pauvres.5

Vous avez probablement des faits intéressants sur le rôle de ces matières cireuses. Evidemment elles abritent le tissu contre l’humidité, mais ceci n’est guère avantageuse aux plantes que dans les pays très humides. Elles abondent sur les surfaces dépourvues de stomates ou qui ont peu (fruits de pruniers, plantes grasses etc), surfaces qui évaporent faiblement, et la matière cireuse s’oppose encore à l’evaporation. C’est avantageux dans les pays secs, mais dans les pays humides au contraire il semble avantageux à une plante d’evaporer librement ce qu’elle absorbe par les racines. Même dans les pays secs il est bon qu’une plante puisse absorber exceptionnellement la rosée ou la pluie, par les surfaces exposées à l’air, puisque les racines fournissent peu d’eau (On a démontré que les feuilles fanées absorbent de l’eau liquide). Ainsi la couche cireuse des Echeveria, Mammillaria etc, du plateau méxicain,6 parait tantot avantageuse et tantot nuisible. Mais il y a peut-être d’autres effets que vous connaissez et qu’on sera heureux d’apprendre de vous.

Mes compliments, je vous prie, à Monsieur Francis,7 en croyez moi toujours, mon cher Monsieur, votre très dévoué et affectionné | Alph. de Candolle

CD annotations

2.3 Schnyder] scored and underl red crayon
2.3 Schnyder … Buenos-Ayres 2.4] scored red crayon
2.4 Buenos-Ayres] underl red crayon
2.8 à … de vous. 3.14] scored red crayon

Footnotes

For a translation of this letter, see Appendix I.
See letter from Alphonse de Candolle, 14 August 1877. CD was investigating the function of the bloom on the leaves and fruits of certain plants (see letter to Alphonse de Candolle, 3 August 1877).
Anton de Bary was professor of botany at Strasburg University, and Jules Emile Planchon was professor of botany at Montpellier. Their participation in the botany section of the meeting of the Swiss Society for Natural Sciences held in Bex from 20 to 22 August 1877 was noted in Société helvétique des sciences naturelles 60 (1877): 77–9.
Otto Schnyder presented a paper on the distribution of plants in the Argentine Republic at the meeting in Bex (Société helvétique des sciences naturelles 60 (1877): 79); it was published in Archives des sciences physiques et naturelles, the journal of the Société de physique et d’histoire naturelle de Genève (Schnyder 1877).
CD’s question, and the responses from de Bary and Schnyder, were briefly noted in Société helvétique des sciences naturelles 60 (1877): 79. Musa is the genus of bananas and plantains, Strelitzia is the genus of bird-of-paradise plants, and Cannaceae is a tropical family of large-leaved flowering plants.
Echeveria is a genus of drought-resisting succulent plants, and Mammillaria is the genus of pincushion cacti.
Francis Darwin.

Bibliography

Schnyder, Otto. 1877. Contributions à la connaissance de la flore Argentine. Archives des sciences 60: 407–32.

Translation

From Alphonse de Candolle1   8 October 1877

Geneva

8 Oct. 1877

My dear Sir,

I can add a few words more to my letter of August on plants with glaucous material.2 This is more in support of my doubts, rather than to allay them, but nonetheless on one point I will be more positive.

In the last session of the Swiss Society of Natural Sciences, at Bex, we had in the Botany section Mr de Bary and Mr Planchon, apart from a number of Swiss botanists.3 A young native of Lucerne, Mr Schnyder, professor of botany at Buenos Aires, read an interesting paper on the physical geography and botany of the Argentine republic.4 He characterised five very different regions, some very humid and others very dry. I took the opportunity to raise your question on the proportion of glaucous plants in different regions of the globe. They agreed with me that it is impossible to give such proportions, since grey species are described as glaucous, and in particular because of intermediates between very visible glaucous material and that which is transparent or much less apparent. Glaucous plants (real and definite) in hot and humid countries, like Musa, Strelitzia, Cannaceae, etc, were mentioned but no one could say what proportion of the equatorial flora they comprised. On my specific question: whether glaucous plants were not numerous in dry areas; Mr Schnyder confirmed my opinion. He saw them often in arid regions of La Plata, and this in a seemingly significant proportion for extremely poor flora.5

You probably have interesting facts on the role of these waxy materials. They evidently protect against moisture, but this is hardly advantageous except for plants in very wet areas. They are plentiful on surfaces devoid of stomata or that have few (plums, thick-leaved plants etc), surfaces that evaporate weakly, and the waxy material further inhibits evaporation. This is an advantage in dry areas, but in wet areas on the contrary it seems advantageous for the plant to evaporate freely that which is absorbed by the roots. Even in dry areas it is good if a plant can, in exceptional circumstances, absorb dew or rain by the surfaces exposed to the air, since the roots supply little water (It has been shown that wilted leaves absorb water in liquid form). Thus the waxy coating of Echeveria, Mammillaria, etc, of the Mexican plateau,6 seems sometimes advantageous, and sometimes detrimental. But perhaps there are other effects that you know of and which we would be happy to learn about from you.

Please give my regards to Mr Francis,7 and believe me always to be, dear sir, your devoted and affectionate | Alph. de Candolle

Footnotes

For a transcription of this letter in its original French, see pp. QQQQ
For a translation of this letter, see Appendix I.
See letter from Alphonse de Candolle, 14 August 1877. CD was investigating the function of the bloom on the leaves and fruits of certain plants (see letter to Alphonse de Candolle, 3 August 1877).
Anton de Bary was professor of botany at Strasburg University, and Jules Emile Planchon was professor of botany at Montpellier. Their participation in the botany section of the meeting of the Swiss Society for Natural Sciences held in Bex from 20 to 22 August 1877 was noted in Société helvétique des sciences naturelles 60 (1877): 77–9.
Otto Schnyder presented a paper on the distribution of plants in the Argentine Republic at the meeting in Bex (Société helvétique des sciences naturelles 60 (1877): 79); it was published in Archives des sciences physiques et naturelles, the journal of the Société de physique et d’histoire naturelle de Genève (Schnyder 1877).
CD’s question, and the responses from de Bary and Schnyder, were briefly noted in Société helvétique des sciences naturelles 60 (1877): 79. Musa is the genus of bananas and plantains, Strelitzia is the genus of bird-of-paradise plants, and Cannaceae is a tropical family of large-leaved flowering plants.
Echeveria is a genus of drought-resisting succulent plants, and Mammillaria is the genus of pincushion cacti.

Bibliography

Schnyder, Otto. 1877. Contributions à la connaissance de la flore Argentine. Archives des sciences 60: 407–32.

Summary

Speculates that the function of "bloom" is to prevent evaporation.

Raised CD’s question about the geographical distribution of glaucous plants at recent botanical meeting.

Letter details

Letter no.
DCP-LETT-11173
From
Alphonse de Candolle
To
Charles Robert Darwin
Sent from
Geneva
Source of text
DAR 161: 23
Physical description
3pp (French) †

Please cite as

Darwin Correspondence Project, “Letter no. 11173,” accessed on 26 October 2021, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-11173.xml

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