A candidate for the highest flowering plant in the world is Christolea himalayensis of the Crucifer family, which was recorded at 6300 m on India’s Mount Kamet in the Western Himalayas. Its grey leaves are hard to spot , but the flowers, “yellow suffused with pink”, are bright among the rocks. As Toshio Yoshida describes in Portraits of Himalayan Flowers, the plant “grows on bleak, unstable screes” that freeze and thaw everyday, throughout the year.
Another record-breaking plant, Purple saxifrage – Saxifraga oppositifolia, was found in the Swiss Alps, close to the summit of the Dom (the third highest peak of the Alps).
Although at 4,505 m the site is nearly 2,000 m lower than for C. himalayensis, the conditions the Purple saxifrage faces here are more gruelling, according to the discoverer Professor Körner:
We believe that it is the coldest point on earth at which a bloom plant can flower.
The ground here is free of snow for only 2 months a year, and every night the temperatures drop below zero. This wonderfully adapted plant only needs an annual 600 hours of temperatures above 3 degrees to survive.
Unsurprisingly then, Purple saxifrage also appears in the most northerly plant locality in the word, growing on Kaffeklubben Island in north Greenland. Its flowers are semi-sweet and edible.
See also high altitude flora in the PyreneesSome possibly unrelated posts