Aconitum delphinifolium is flexuous herb with distinctive deep-purple hooded flowers and deeply lobed leaves, common throughout Denali in lush sites from shady woods into alpine meadows. Plants grow 20-50 cm tall from a corm-like rhizome. Leaves are alternate, gracefully palmatelylobed and deeply cleft into narrow segments, round in outline. The upper stem leaves are two-lobed or linear. Stems are green, glabrous and flexuose. Monkshood inflorescences have 1-5 flowers in an open raceme. The bilaterally symmetric flowers are deep purple to lilac, strongly veined, with five petal-like sepals and two distinctive petals hidden within. The uppermost sepal is helmet-like, sitting over the upper edges of two wide, vertically aligned sepals, the last two petals ovate, flat. The petals are long-clawed, beaked at the apex, paler purple. Each flower produces 3 (sometimes 5 or more) follicles, 1.5-2 cm long, which contain many black seeds. Plants could potentially be confused with larkspur (Delphinium species), which also have deeply lobed leaves and bilaterally symmetric blue-purple flowers. However, the flowers of larkspur have an elongate spur in the back, not a hoodlike flower.
This species is perennial, flowering in mid-summer and fruiting in mid-late August.
A. delphinifolium flowers are bisexual and bee pollinated. The breeding system of this species has not been studied. Each flower produces 3 (sometimes 5 or more) follicles, which contain many black seeds, dispersed by gravity and wind.
The entire plant contains aconitine, a neurotoxin.
Monkshood is an amphi-Beringian endemic species that occurs in Alaska, Northwest Territory, Yukon, the northern half of BC, western Alberta and across the Bering Strait in Eurasia. The species occurs throughout Alaska. Aconitum delphinifolium occurs widely across the full extent of Denali, and is especially common in subalpine areas on both sides of the AK Range, and in meadows along rivers in the boreal zone.
The abundance of monkshood in Denali peaks at 900-1100 meters, though it occurs at all elevations (a range of 90-1572 m). This species is slightly more common on southern aspects. Additionally, its frequency of occurrence increases with increasing slope, and the average site is at a 13 degree incline.