Plant Collector George Forrest (1873-1932) introduced over 300 new rhododendron species to Britain but one in particular dwarfed all of these, Rhododendron protistum, which is represented in our collection by a large slice of tree trunk, felled by Forrest and his collectors in 1931 – it may even be our largest herbarium specimen?

The slice of tree trunk – just over 65cm at its widest point.

Forrest referred to his find as Rhododendron giganteum – an appropriate name!  He discovered both R. protistum and giganteum during his fourth expedition to Yunnan in southwest China between 1917 and 1920, but they were mistakenly identified as being different species – Forrest’s find in March 1931 changed all that.  He took a sample and sent it to RBGE Regius Keeper William Wright Smith as soon as he could.  Forrest himself takes up the story:

“Towards the end of next week I am sending off to Cook, Rangoon, to be forwarded to you a case containing a large cross-section of a tree of Rhododendron giganteum which I secured during my journey. The section enclosed is stenciled as follows –

Rhod giganteum

specimen of fully 90ft

section cut 12ft from base

cut 15/3/31

GF

You may like to have it for the Garden Museum, and in any case it will be an object of interest to those rhododendron people who may visit the RBG during the season.”

“We found it at its best – in almost full flower, thousands of trusses of huge blooms of varying shades of rose-pink to almost magenta-crimson, the ground under each tree littered inches deep with the huge fallen corollas.

“From our specimen I finally proved one thing, that Rhododendrons giganteum and protistum are one and the same species, as I collected from it not 2, but 3 forms of foliage. The original specimens of R. protistum must have been collected from a young giganteum! So you’ll have to cut out one name and according to [taxonomic] priority Rhod. protistum has it. But I should like giganteum to stand for the name is most fitting! Don’t you agree?”

G.Forrest to W.W.Smith; 31/03/1931; from Tengyueh (Tengchong)

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Unfortunately, as Forrest correctly points out, Rhododendron protistum was named before the mis-identified giganteum, so this was the name which had to remain.

Forrest’s collectors cutting up the massive rhododendron.