Woolly geranium is a medium-sized forb with open purple flowers and deeply and repeatedly-lobed leaves. This species grows in lush meadows and forest edges, and is much more common on the southern slopes of the Alaska Range than in the interior areas of Denali. Plants grow 20-50 cm tall from a rhizome. The leaves grow from long petioles, in opposite pairs on the stem. They are rounded in outline, but palmately divided many times, the edges roughly toothed. At the top of the plant, there is a branched inflorescence, with clusters of 1-5 flowers. The green sepals are densely woolly, beneath the petals. The five petals are obovate with round tips, hairy on the inside at the base, lilac-purple, each petal with several prominent veins of darker violet radiating from the center. The 10 stamens have hairy filaments and purple anthers, surrounding the single pistil. The flowers develop into elongate seed capsules, 2.5-3 cm long—the shape is source of another common name, 'crane's bill. ' These split open along four seams, flinging the tiny seeds outwards.
Geranium erianthum is perennial and deciduous. It typically flowers mid-summer in Denali.
Geranium erianthum is monoecious with bisexual flowers. Flowers are insect pollinated. Seeds are flung out when the capsule splits open.
The Aleut traditionally prepared geranium leaves as a sore throat gargle, Kodiak Island natives chewed the roots to treat tuberculosis, and the Dena'ina used an infusion extensively for a variety of external and internal ailments (Garibaldi 1999).
Geranium erianthum is a coastal amphi-Beringian species that occurs from B.C. northwest through southern Alaska and Yukon (including the entire Aleutian chain) into Kamchatka and Chukotka, southwards in Asia to Japan. In Denali, this species is common and locally abundant south of the Alaska Range crest, and occurs in scattered localities in the mountains to the north.
In the Park, northern crane's-bill grows at a large range of elevations (136 to 1470 m), with most localities occurring around 800 m. This is a species of south-facing slopes; the average incline is 17 degrees.