Heracleum maximum

Native

Moist. Stream banks, river banks, disturbed sites. Full to partial sun.

June to July

White

3′ to 10′

This is a 3′ to 10′ tall, erect, perennial forb that rises on a single stem from a stout taproot. The foliage has a foul smell.

The stems are erect, stout, unbranched below the inflorescence, hollow, and grooved. They are sparsely to densely covered with spreading, easily visible hairs.

The leaves are alternate, 4″ to 19″ long, and palmately divided into 3 leaflets. The uppermost leaves are sometimes only about 2¾″ long and 3-lobed, not compound. The lower leaves are on long leaf stalks. The leaf stalks become shorter as they ascend the stem, with upper leaves appearing almost stalkless. The base of the leaf stalk sheathes the stem. The sheath of the middle and upper leaves is moderately to strongly inflated and moderately to densely covered with spreading hairs.

The leaflets are 4″ to 12″ long and wide, egg-shaped to almost circular in outline, palmately 3-lobed, and stalked. The lobes are shallowly to deeply and taper to a sharp, abrupt point at the tip. The lateral leaflets are narrower than the terminal leaflet and are often asymmetrical. The upper surface is hairless. The lower surface is covered with spreading hairs, especially along the main veins and near the base. The margins are coarsely toothed.

The inflorescence is a broad, flat-topped, terminal umbel at the end of the stem and smaller umbels rising from the upper leaf axils. The terminal umbel is round, long-stalked, and usually 4″ to 12″ but up to 16″ in diameter. It is composed of usually 15 to 30 but up to 45 umbellets.

The flowers have 5 white, notched petals. The outer flowers of the marginal umbellets are irregular, the outer petals enlarged and often cleft into two deep lobes at the tip. The flowers are fragrant.

The fruit is dry, ⅓″ to ¾″long, egg-shaped to globular, and 3-angled. It is tan to straw-colored and has prominent, purple stripes (oil tubes) between the ribs. It contains 2 seeds. The seeds are flattened on one side, rounded on the other. When ripe the fruit splits into 2 one-seeded segments.

Purple-stem angelica (Angelica atropurpurea) stem is hairless. The sheath at the base of the leaf stalk is not inflated or are only slightly inflated. The leaves are ternately compound then pinnately compound with 5 or 7 leaflets. The leaflets are 4″ to 12″ long and wide, egg-shaped to almost circular in outline, and palmately 3-lobed. The umbels are globular, not flat-topped.