Polar Dwarves

Dwarf hawksbeard, Crepis nana, lacks stems altogether.

Many arctic plants are small and grow close to the ground. Saxifrages and arctic willow are typical examples of this strategy. Their ground-hugging morphology is advantageous because temperatures on sunny days are 5°C to 10C warmer near the soil surface than even a few centimetres above it! This is due to the dark colour of the soil which absorbs sunlight and radiates heat. With these extra few degrees in temperature, the plants can grow and develop much more quickly. In fact, with 24 hours of sunshine in the summer months, arctic plants can sometimes grow faster than temperate plants!

Dwarf hawksbeard blooms while its flowerheads still touch the basal rosette of leaves – essentially, they lack stems! This adaptation keeps the seeds close to the warmer air, so the plant can reproduce successfully. In addition, remaining low to the ground helps these plants avoid damage from blowing snow and to reduce wind-induced desiccation. If these dwarf plants were transplanted to a temperate region, where the summers are longer and milder, many would grow to more than double their arctic size!