Diapensia

Diapensia lapponica, the pincushion plant, is a plant in the family Diapensiaceae, the only circumboreal species in the genus Diapensia, the others being mainly in the Himalaya and on mountains in southwestern China. This species likely became circumboreal-circumpolar [Arctic–alpine] after it jumped to arctic habitat from North China and Russia. The most likely candidate for ancestor is a white-flowered D. purpurea The plants grow on exposed rocky ridges that are kept free from snow by high winds.

Diapensia lapponica is extremely slow and low-growing and cannot compete with plants that overtop it. The plant is very sensitive to higher temperatures and so is often in misty foggy habitat. It usually dies when transplanted to lowland gardens and so this is not recommended. Cold-treated or wild and winter-collected seed will germinate indoors. The seed and leaves are high in lipids.

It is a small cushion-forming evergreen perennial shrub, up to 15 centimetres (6 in) in height, and can trap heat in the dome. It has oval blunt leathery toothless leaves, up to 1 cm (0.4 in) long, which are arranged in dense rosettes. It bears solitary white flowers (rarely pink), on stems up to 3 cm (1.2 in) tall.

It could be aged by counting growth-rings or clump diameter, and on this basis, many Canadian plants are thought to live to over a century or two.

In places such as Newfoundland two blooming periods exist on different plants: early June and (more frequently) August. It is not known if this is a genetic or environmental affect. Two blooming periods are known for other plants. It often involves flower buds being formed in the present or previous year (overwintering buds).