Montana Field Guide

Hemlock Parsley is a perennial herb with simple stems which are 3-10 dm high and arise from a club-shaped taproot or cluster of fleshy roots and a simple or little-branched rootcrown. The alternate leaves are divided into 7-11 leaflets, the lower of which are divided 2-3 more times. The leaves are triangular in outline and 3-19 cm long with a 3-23 cm long petiole and a dilated sheath at the base. Ultimate leaf segments are less than 3 mm wide. The foliage is glabrous below the inflorescence. Small, white flowers occur in hemispherical clusters borne at the ends of 9-15 stalks, which are arranged in an umbrella-shaped inflorescence, or umbel; the umbel is 3-10 cm in diameter and is located at the top of the stems. Each cluster of flowers is subtended by 3-6 thread-like bracts, which comprise an involucre that is 2-8 mm long. The flattened, egg-shaped fruits are 4-6 mm long and have corky, thickened margins and a conspicuous thickening at the top at the base of the style, known as a stylopodium.

Fruiting in July.

Species in Apiaceae are often difficult to distinguish; a hand lens or microscope and identification manual are necessary. Hemlock Parsley can be distinguished from members of the closely-related genus Ligusticum by the involucre of 3 or more bracts and by the lack of stringy old leaf bases at the summit ofthe rootcrown.

Riparian forests and moist meadows in the valleys.