Darwin did not mention plants in his records of his visit to Tasmania except on his visit to Mount Wellington when he commented on the Eucalypts and the Tree Ferns:

“In many parts the Eucalypti grew to a great size and composed a noble forest. In some of the dampest ravines, tree-ferns flourished in an extraordinary manner; I saw one which was at least twenty feet to the base of the fronds, and was in girth exactly six feet. The fronds forming the most elegant of parasols, produced a gloomy shade, like that of the first hour of the night.”
[Charles Darwin, Journal of Researches, London, 1839].

Myrtaceae - Eucalyptus  globulus - Blue Gum  Tasmanian Herbarium specimen collected by Winifred Curtis 1942	Cytheaceae - Cyathea australis - Tree FernTasmanian Herbarium specimen collected by Ronald Campbell Gunn 1844

Ronald Campbell Gunn

Ronald Campbell Gunn was the outstanding naturalist resident in Van Diemen’s Land.  He collected specimens for J.D. Hooker, and Flora Tasmaniae was dedicated to him.  Earlier Gunn had collected for William Hooker, J.D.’s father, writing one of many letters to him on the very day Darwin arrived in Hobart, 5 February 1836.  Both Hookers served as directors of Britain’s national herbarium.

Joseph Hooker

Hooker’s work, The Botany of the Antarctic Voyage of  H.M. Discovery Ships Erebus and Terror III. Flora Tasmaniae was published in 1860, just a few weeks after On the Origin of Species and its support of Darwinian ideas did much to further their acceptance.

When Hooker, who was a friend of Darwin’s, wrote to tell him of the Tasmanian Government’s contribution of 350 pounds towards the cost of publishing the Flora Tasmaniae Darwin responded “What capital news from Tasmania: it really is very remarkable & creditable fact to the Colony: I am always building veritable castles in the air about emigrating, and Tasmania has been my headquarters of late so that I feel very proud of my adopted country: it really is a very singular & delightful fact, contrasted with the slight appreciation of science in the Old Country.”

Joseph Hooker, 1817-1911. botanist and friend of Darwin	Hooker, J. D. 1860: The Botany of the Antarctic Voyage of  H.M. Discovery Ships Erebus and Terror III. Flora Tasmaniae  Lovell Reeve, London
Introductory essay of Part 111, Flora Tasmaniae in which Hooker acknowledges the work of Darwin.	Hooker's dedication to Ronald Campbell Gunn and William Archer in Flora Tasmaniae