white-flowered leafcup

not listed

N5 - Secure

SNR - Unranked

not listed

White-flowered leafcup is a large but little-known woodland wildflower. It occurs in the United States from Vermont to Georgia, west to Minnesota and Oklahoma, and in southern Ontario Canada. In Minnesota it is mostly restricted to the southeast corner of the state, where it reaches the northwest extent of its range. It is found in woodlands and forests. It grows under medium to light shade, in moist, loamy, limey (calcareous) soil.

White-flowered leafcup is an erect, perennial forb that rises on multiple stems from fibrous roots and usually also from underground stems (rhizomes). It sometimes forms colonies. It can be 20″ to 70″ (50 to 180 cm) tall, but in Minnesota it is usually no more than 48″ (120 cm) in height. The stems and leaves are not fragrant when crushed.

The stems are erect or ascending and usually have several branches toward the top. The upper stem is moderately to densely covered with long, soft, straight or shaggy hairs, and also with gland-tipped or sticky hairs. The lower stem is hairless or nearly hairless.

The leaves are opposite and mostly 1½″ to 8″ (4 to 20 cm) long, and ¾″ to 4¾″ (2 to 12 cm) wide, on 1¼″ to 3⅛″ (3 to 8 cm) long leaf stalks (petioles). The largest lower leaves are sometimes much larger, up to 16″ (40 cm) long and 10″ (25 cm) wide on up to 4¾″ (12 cm) long petioles. The petioles are green or purplish near the base, grooved on the upper side, and covered with short, soft, glandular hairs. They are sometimes winged for a short distance but only near the blade. Larger leaves often have a rounded leaf-like appendage (stipule) at the base that wraps around the stem. Opposite stipules sometimes fuse together creating a short cup. This is the feature that gives the species its common name.

Lower leaf blades are rounded to heart-shaped or egg-shaped in outline and are often deeply cut into 5 to 7 lobes. They are mostly broadly tapered at the base. The lobes are sharply pointed at the tip. The upper surface is dark green and may be hairless or sparsely to moderately covered with short, soft, curved, sometimes gland-tipped or sticky hairs. The lower surface is pale green and is sparsely to moderately covered with short, gland-tipped or sticky hairs, especially near the main veins. The margins are finely to coarsely toothed. Upper leaf blades are smaller, triangular or egg-shaped, and mostly unlobed.

The inflorescence is a loose, branched, often spreading or nodding cluster of 2 to 5 flower heads at the end of the stem and branches. Each division of the cluster is subtended by a pair of modified leaves (bracts). Flower stalks (peduncles) are densely covered with glandular hairs. At the base of each flower head there is a 3⁄16″ to ⅜″ (5 to 9 mm) long, ¼″ to ½″ (6 to 13 mm) in diameter, cup-like whorl (involucre) of 6 to 21 bracts (phyllaries) in two series. The phyllaries are moderately to densely covered with sticky or gland-tipped hairs on the outside. The inner phyllaries are egg-shaped to broadly inversely egg-shaped and are loosely ascending. The outer 2 to 4 phyllaries are lance-shaped to narrowly egg-shaped, slightly longer and narrower than the inner ones, and widely spreading or curved backward.

Each flower head has 5 to 8 ray florets and a central disc with 26 to 40 disc florets. The rays are sometimes reduced to just a minute tube with no flat, petal-like portion (ligule). When a ligule is present it is white, widely spreading, and small, 1⁄16″ to ⅜″ (2 to 10 mm) long, with three rounded lobes at the tip. The disc florets have 5 petals fused at the base and for most of their length into a tube, then separated into 5 short lobes. The corolla is pale yellow and ⅛″ (3 to 4 mm) long.

Each ray floret is replaced by a single fruit. The fruit is a dry, ⅛″ (3 to 4 mm) long capsule (cypsela) with a single seed. The cypsela is dark brown to black, usually with some reddish mottling, and is bluntly 3-angled or sometimes ribbed.

20″ to 70″ (50 to 180 cm)

White ray florets, pale yellow disk florets

Moist. Woodlands, forests. Medium to light shade. Calcareous soil.

June to September

Sources

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

Native

Plant

Leaves

Location: Great River Bluffs State Park