Northern Monk's hood is an upright herbaceous perennial, with alternate leaves. Each leaf is made up of five to seven wedge-shaped, coarsely-toothed lobes. The stem is topped by a spike of dark purple to blue (rarely white), larkspur-shaped flowers, with "hoods" on the top.

While it's possible to identify this plant in fruit, or even from dried persisting fruit stalks, for easy identification it is best to search for it in flower.

The shape of the flowers makes this genus distinctive. Garden aconite (Aconitum napellus), is the only other species of Aconitum found in New York. It is a stouter plant, with larger flowers and more deeply cleft leaves. It is rare that this species would escape from gardens and unlikely for it to co-occur with our native species. For leaf identification the following characters should be useful: Aconitum has 5 "leaflets" that are joined at the base and not on separate petioles as in Ranunculus hispidus. The first lobes from the bottom of the leaflets of Aconitum are large and angle out from the leaflet with usually 2-3 additional big secondary lobes. Leaves of Ranunculus acris are similar but in Geranium maculatum the first lobes are not much larger than the upper central leaflet and usually have small secondary lobes on them. Ranunculus hispidus has leaves with mostly three leaflets that are stalked. Ranunculus recurvatus has a central leaflet sometimes without the two larger lobes or the lateral lobes have small secondary lobes like Geranium. Ranunculus acris has unlobed basal leaves and upper leaves with a few narrow leaflets. Aconitum petioles are glabrous or have tiny white hairs that arch over and the blades are glabrous or with scattered tiny white hairs. The secondary veins are faint. Geranium maculatum and other similar Ranunculus species have sparse to dense long white hairs that cover the petiole and leaves.