American gromwell

not listed

N4 - Apparently Secure

SNR - Unranked

not listed

American gromwell is a spring woodland wildflower. It occurs in the United States from New York to Minnesota, south to Virginia and Kansas, and in southern Ontario Canada. It is uncommon throughout its range, including in Minnesota. It mat be often overlooked due to the small size of its flowers and its similarity in appearance to other much more common plants. It is found in upland, moderately moist forests, woodlands, and thickets, usually on north-facing slopes; and on roadsides. It grows in rich, loamy soil under dappled sunlight in the spring, medium shade in the summer. Its presence is an indicator of a high quality woodland.

American gromwell is an erect, perennial forb that rises on one or a few stems from a stout, somewhat woody taproot. It can be 16″ to 40″ tall, but in Minnesota it is usually no more than 30″ in height.

The stems are erect and may be unbranched or have a few branches. They are moderately to densely covered with white, stiff, appressed, upwardly curved hairs.

The leaves are alternate, ¾″ to 5½″ (2 to 14 cm) long, and 5⁄16″ to 2⅜″ (8 to 60 mm) wide. They are stalkless or on very short leaf stalks. The leaf blades are lance shaped to narrowly egg-shaped, angled or tapered at the base, and tapered to a sharp point at the tip. There are 3 or 5 lateral veins that arch strongly toward the leaf tip. They are conspicuously sunken on the upper surface and raised on the lower surface. The upper surface is dark green and rough to the touch. It is moderately covered with minute stiff hairs, and sparsely covered with longer spreading hairs. The lower surface is grayish-green and is moderately to densely covered with short, soft, fine hairs. The margins are untoothed.

The inflorescence is a solitary flower on a short stalk in each of the upper leaf axils. Self-pollinating, closed, bud-like (cleistogamous) flowers are not produced.

The flowers are 3⁄16″ to 5⁄16″ (5 to 8 mm) long and about ¼″ wide. There are 5 outer floral leaves (sepals), 5 petals, 5 stamens, and 1 style. The sepals (together the calyx) are green and are fused just at the base then separated for most of their length into 5 hairy, linear lance-shaped, 3⁄16″ to 5⁄16″ (5 to 8 mm) long lobes. The petals (together the corolla) are pale yellow to greenish-white. They are fused at the base into a narrow, ⅛″ to ¼″ (4 to 6 mm) long floral tube, then separated into 5 widely spreading, 1⁄32″ to 1⁄16″ (1 to 1.5 mm) long lobes. The corolla tube is no longer than the lobes of the calyx. The corolla lobes are not fringed. The stamens are inserted near the middle of the corolla tube. The style is 1⁄32″ to 1⁄16″ (1 to 2 mm) long.

The fruit is a shiny, white, hard, egg-shaped, ⅛″ to 3 ⁄16″ (3.5 to 5 mm) long nutlet. It has a blunt ridge (keel) on the bottom. It may be smooth or have shallow scattered pits, mostly toward the base and along the keel. Each nutlet contains 1 seed. The calyx lobes persist and become 3 ⁄16″ to ½″ (5 to 8 mm) long and erect in fruit.

16″ to 30″

Pale yellow to greenish-white

Dry to moist. Upland, moderately moist forests, woodlands, and thickets, usually on north-facing slopes; roadsides. Dappled sunlight in the spring, medium shade in the summer. Rich, loamy soil.

May to June

Sources

2, 3, 4, 5, 7, 24, 28, 29, 30.

Native

Uncommon

Plant

Inflorescence

Flower

Leaves

Location: Owatonna, MN

Found this plant yesterday growing on the trail near Mineral Springs Pk., Owatonna.