Vol 25, no 3, October - The Linnean Society of London

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THE LINNEAN 2009 VOLUME 25(3)
lying, there were in the clefts of the rocks a few Cacti. These are supported by the dense
clouds which generally rest on the land at this height… This is the first true desart I
have ever seen; the effect on me was not impressive…” (Keynes 1988: 345-346).
Darwin’s unknown soil lichen is most likely Vermalicina tigrina (Spujt 1995,
1996), described by Gerhard Follmann as Ramalina tigrina (Follmann 1966), 131
years after its initial discovery, although no specimen of it has been found attributable
to Darwin. His observations on the relationships of cloud, cacti and lichens, are the
first I know of, of the “camanchaca” (the South American vernacular name for the
cold coastal fog that sweeps in from the Pacific to drape the coastal ranges and their
“cactus forests”) and its influence on lichen distribution in these fascinating fog-oases
that are characteristic of the north of Chile and found also in Peru, Baja California and
Namibia. Although in recent years, the characteristic North Chilean coastal lichen
mycobiota has been in alarming decline (Follmann 1995), Darwin’s “lichen oasis”
was rediscovered by Gerhard Follmann in the early 1990s when a few SW-facing
clefts of the outer ridges of the coastal cordillera between 800 and 900 m, revealed
large mats of soil lichens developed between sparse skeletons of the columnar cactus
Eulychnia iquiquensis. Here, Darwin’s greenish lichen, V. tigrina, associates with
Heterodermia leucomela, Ramalina celastri, R. cochlearis, R. peruviana, R. pilulifera,
Roccellina suffruticosa and Xanthomendoza mendozae (Follmann 1994).
8. Peru: The Beagle anchored at Callao on 19 July 1835 and Darwin stayed in
Lima for 6 weeks (Burkhardt & Smith 1985: 541), during which time he visited the
island of San Lorenzo. In a letter to Joseph Hooker on 16 April 1845 he wrote “…The
enclosed little lichens, came from near the summit of most barren isl d of San Lorenzo
off Lima: what on earth made me think them worth collecting I know not – please
throw them away…” (Burkhardt & Smith 1987: 177). To this Hooker replied on 28
April 1845 “…The St Lorenzo Lichen I can make nothing of but have sent it to D r
Taylor, with no hopes however: as I could not find fructification. You notice somewhere
a blown-about-Lichen on the Andes, at Quillota is it? – it is an Usnea perhaps the
Antarctic U. melaxantha but the specimens are very imperfect …” (Burkhardt & Smith
1987: 183). This refers to the lichen Ramalina tigrina, that Darwin had found on sand
above Iquique (see above).
9. Galapagos Islands: The Beagle stayed at the Galapagos Islands from 15
September until 20 October 1835 (Burkhardt & Smith 1985: 541). In his Journal Darwin
noted “…The tortoises which live on those islands where there is no water… feed
chiefly on the succulent cactus. …and likewise a pale green filamentous lichen (Usnea
plicata), that hangs in tresses from the boughs of trees…” (Darwin 1845). Joseph
Hooker lists three lichens from the Galapagos all collected by Darwin viz. Usnea
plicata [= U. articulata], Borrera leucomelos [= Heterodermia leucomela] and Sticta
aurata [= Pseudocyphellaria aurata] (Hooker 1851).
Darwin’s place in South American lichenology
The great South American traveller and observer, Alexander Humboldt (1769-
1859), makes a fascinating comparison of Darwin with George Forster as a gifted
observer of nature as shown in the following extract from Cosmos, “…I have here
attempted to indicate the direction in which the power possessed by the observer of
representing what he has seen, the animating influence of the descriptive element, and