As the highest mountain in Africa, Kilimanjaro itself is pretty outstanding. But as a free-standing mountain whose climate zones become progressively less like the ground-level landscape the further you ascend, Kilimanjaro is especially remarkable as an incubator for isolated, mutated, or rare species found almost nowhere else.
One of the most striking of those species is the giant groundsel varietal Dendrosenecio kilimanjari.
A giant groundsel near Barranco Camp, Mt. Kilimanjaro
“Senecio Kilimanjari” by Dfmalan – Own work. Licensed under Public Domain via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Senecio_Kilimanjari.jpg#mediaviewer/File:Senecio_Kilimanjari.jpg
Something like a cross between a burned-up cactus and a pineapple, these alien-looking plants can only be found on Kilimanjaro, and only above 14,000ish feet (related, but similarly isolated sub-varieties of giant groundsel can “only be found” on a handful of other East African mountains).
In order to carve out an existence in such a forbidding environment—that high up the mountain, temperatures regularly dip below freezing overnight—the plants have evolved water storage in the pith of the stem, nyctinastic leaf movement (which means the leaves close when the temperature drops too far), a natural “anti-freeze,” and self-insulation through withered and dead foliage (part of the reason the groundsels look so strange).
Evolution is really the name of the game for giant groundsels, both on Kili and on other East African mountains. None of the species are exactly the same, but it’s guessed that they all evolved from a common groundsel around a million years ago, climbing higher and higher up the slopes via the slow process of windborne seed distribution (which would move the plants no more than a few meters at a time).
Just for reference, this is a common groundsel:
Common groundsels look (and act) a lot like dandelions, and are considered weeds by most gardeners
“Common Groundsel-first fruits” by carol – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Common_Groundsel-first_fruits.jpg#mediaviewer/File:Common_Groundsel-first_fruits.jpg
Common groundsels like the one pictured above range from 4-16” tall. Giant groundsels, on the other hand, regularly grow over 10 feet tall, sometimes even 20 feet or more!
It seems fitting: the tallest free-standing mountain in the world has the tallest mutant weeds!