Update (Feb. 28, 2006 2:13 PM PST): Changed accession number on entry to reflect Brent's comments below.
Ideally, every plant in a botanical garden should be identified and named. Sometimes, for any of a number of reasons, the ideal is not reached.
This lupine is a good example. Wild collected in Patagonia in the early 1980s, it is labelled (and in our database) as Lupinus sp. aff. mutabilis. The original assessment of the plant was that it resembled Lupinus mutabilis, but the collector was not willing to affirm its identity one hundred percent.
For twenty-three years now, this plant has quite happily grown in the South American section of the Alpine Garden. In that time, none of the staff or researchers have been able to decipher its true identity due to a gap in our library. Generally we'd need either a comprehensive guide to either the plants of Chile and / or Argentina (a flora) in our library, or, alternatively, a scientific work that describes the Lupinus of the region or the world (a monograph). Without a step-by-step key to identify plants in the genus Lupinus of that region, any moniker we attach to the plant is scientifically known as a “guess” - and makes the plant even less valuable to researchers. In the case of using plants for research, it is better to be uncertain than to be wrong. So, for the time being, this plant remains a beautiful mystery.
Dr. Quentin Cronk requested a comment by Dr. Colin Hughes (Dept. of Plant Sciences at Oxford) about this mystery. Dr. Hughes had this to say:
“My guess is that it is an introduced North American species, or a hybrid between two North American introductions, but I am still not familiar enough with all of the North American perennials (yet!) to make a sensible guess. It is certainly not Lupinus mutabilis - nor, I would guess a spontaneous hybrid involving Lupinus mutabilis. Very doubtful if L. mutabilis would survive in Patagonia anyway.
There are very few (c.5) native Chilean species of Lupinus, all of them in the north, and it does not match any of them. Several North American species, including Lupinus arboreus and Lupinus polyphyllus are introduced and naturalised in Chile. Native Lupinus is similarly absent from southern Argentina, again apart from L. arboreus and L. polyphyllus which both occur widely but sporadically. Thus suspicion must fall on Lupinus polyphyllus and its numerous allies, unless there is an interesting and as yet undocumented surprise lurking down in the Cono Sur.”
One quick search around google will show definitively that the taxa shown is not L. mutabilis nor even close to it. Dr. Hughes likely has it right, that it's in the line of L. polyphyllus. The accesssion number of the plant shown is actually 37235-167-04. Seed came to the garden from the Alpine Garden Club of BC, which means it could have been garden or wild collected. In short, there probably is no undocumented surprise waiting down in the Cono Sur..
L. polyphyllus is a very common escapee in Patagonia. In many areas it is the single most conspicuous spring "wild"flower.
In this area (Bariloche, Argentina) Blue (as in the photo) is the most common but pink, yellow and white are also present to varying degrees.
I have also seen what I believe to be specimens of Lupinus arboreus, but these are much less common and clearly not the plant in the photo.