goat’s rue

not listed

N5 - Secure

S3 - Vulnerable

Special Concern

Goat’s rue is a showy summer wildflower. It occurs in the United States east of the Great Plains. It is rare in Minnesota, where it reaches the northwest extent of its range. It is restricted to a handful of counties in the extreme southeast, and is listed as a special concern species in the state. It is found in prairies, savannas, open woodlands, and roadsides. It grows under full or partial sun, in dry to moderately moist conditions, in sandy soil. Though infrequent, where it occurs it is often in large colonies.

Goat’s rue is an erect, perennial forb that rises on one to several stems from a thick, knobby base (caudex) and long woody roots. It can be 8 ″ to 27½″ (20 to 70 cm) tall but is usually no more than 20 ″ (50 cm) in height. The plant is easy to identify when flowers or fruit are present, difficult to identify when they are not.

The stems are erect or curve up from the base (ascending) and are often clustered. They are usually unbranched but may have one or more weak branches. They are usually densely covered, sometimes moderately covered, with fine, appressed and spreading hairs.

The leaves are alternate, pinnately compound, and 2″ to 6″ long. There are usually 13 to 25 leaflets but there may be as few as 9 or as many as 31. At the base of each leaflet there is a pair of small, leaf-like appendages (stipules). Stipules on lower leaves are narrowly elliptic or lance-shaped to linear and ¼″ to 7⁄16″ (7 to 11 mm) in length. Those on upper leaves are often hairlike. They drop off early. The central axis (rachis) of the leaf is 1½″ to 4¾″ (4 to 12 cm) long.

The leaflets are narrowly elliptic to inversely lance-shaped, narrowly oblong, or linear, ½″ to 13⁄16″ (12 to 30 mm) long, and 1⁄16″ to ⅜″ (2 to 10 mm) wide. They are angled to rounded at the base and taper to a blunt or sharp point at the tip. The midvein of the leaflet usually continues to a needle-like point at the tip. The terminal leaflet is sometimes rounded or notched at the tip. The upper surface is medium green or grayish-green, and may be hairless or moderately to densely covered with short, fine, curved hairs. The lower surface is densely covered with appressed hairs. The lateral veins are noticeable on the underside. The margins are untoothed and usually have a fringe of ascending hairs.

The inflorescence is a short, dense, unbranched cluster (raceme) of 12 to 40 flowers at the end of the stem. The raceme is 1½″ to 3″ (4 to 8 cm) long and is on a ⅜″ to 1¼″ (1 to 3 cm) long stalk. There are sometimes smaller racemes at the tips of the branches. Each flower is on a ⅛″ to ¾″ (4 to 20 mm) long, densely hairy stalk (pedicel). At the base of each pedicel there is a single modified leaf (bract). The bract is 3⁄16″ to ½″ (6 to 12 mm) long, sometimes longer. It withers early but usually remains on the plant throughout the flowering and fruiting time.

Each flower is about ¾″ long and wide. There are 5 outer floral leaves (sepals), 5 petals, 10 stamens, and 1 style. The sepals are light green, densely hairy, and fused for most of their length into a bell-shaped, 1⁄16″ to 3 ⁄16″ (2 to 5 mm) long tube (calyx), then separated into 2 lips, the upper lobe with 2 lobes, the lower lip with 3 lobes. The petals are organized into a typical pea-like arrangement, with an upper banner, a pair of lateral wing petals, and a pair of lower keel petals. The banner is ⅝″ to ¾″ (15 to 19 mm) long, ½″ to 11⁄16″ (12 to 18 mm) wide, broadly kidney-shaped to almost circular, and broadly pointed, rounded, or slightly notched at the tip. It is abruptly bent upward near the base and is keeled for its entire length. The outer surface is hairy. It is green at first, then turns yellow or cream-colored at maturity. The inner surface is white to cream-colored with a yellow patch near the base surrounded by a pink-tinged area. The wings are ½″ to ¾″ (12 to 20 mm) long, 3⁄16″ to ¼″ (5 to 7 mm) wide, rosy pink, oblong egg-shaped, and rounded at the tip. They are angled over and completely cover the keel. The keel is ½″ to ⅝″ (12 to 15 mm) long and 3⁄16″ to ¼″ (5 to 7 mm) wide, boat-shaped, and curved upward at the tip. It is light pink or light yellow with a pink tinge or pink lines. Nine of the stamens have their stalks (filaments) fused together, one is free to below the middle. The anthers are small and yellow. The style is 5⁄16″ to 7⁄16″ (8 to 11 mm) long and has a minute stigma at the tip.

The fruit is a 1¼″ to 2″ (3 to 5 cm) long, ⅛″ to ¼″ (3 to 6 mm) wide pod with 6 to 11 seeds. It is narrowly oblong, straight or slightly curved, and has a slender, often curved beak at the tip. The outer surface is sparsely to densely hairy, light green at first, becoming papery and straw-colored to brown at maturity. The seeds are kidney-shaped and ⅛″ to 3⁄16″ long.

8 ″ to 27½″ (20 to 70 cm)

Yellow or cream colored and rosy pink

Leadplant (Amorpha canescens), with its grayish-green leaflets, looks similar when flowers and fruit are not present. However, its leaflets are rounded to slightly heart-shaped at the base.

Dry to moderately moist. Prairies, savannas, open woodlands, and roadsides. Full or partial sun. Sandy soil.

Mid-June to late July

All parts of the plant are poisonous to both livestock and people.

Sources

2, 3, 4, 5, 6, 7, 24, 28, 29, 30.

Native

Rare in Minnesota

Goat’s-rue Tephrosia virginiana At TNC KWD Cox Unit

Tephrosia virginiana Goat’s-rue at TNC Cox Unit

Goat’s Rue

Goat’s Rue with Blanding’s turtle

Location: Weaver Dunes Preserve, Cox Unit

Goat’s-rue Tephrosia virginiana At TNC KWD Cox Unit

Location: Weaver Dunes Preserve, Cox Unit

Tephrosia virginiana Goat’s-rue at TNC Cox Unit

Location: Kellogg Weaver Dunes SNA, Weaver Dunes Unit

Goat’s Rue