Kansas Wildflowers and Grasses

BRISTLY LOCUST

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Robinia hispida L.

Clay County, Kansas

Height: Shrubs or trees to 13(-30) feet

Family: Fabaceae - Pea Family

Flowering Period: May, June, July

Trunks:

Stems or trunk erect; branches armed, spines .2 to 3.5 inch, hard, stout, young branches also usually densely hispid with reddish-purple hairs; bark gray to grayish brown, somewhat warty, with irregular plates; wood light brown, hard.

Twigs:

Grayish brown to reddish brown, rigid, somewhat rough, hispid to stipitate-hispid, sometimes glabrate; leaf scars triangular to 3-lobed, .08 to .12 inch long, .06 to .1 wide; pith white; buds brown, cone-shaped, to .04 inch, apex obtuse, scales rusty-pubescent.

Leaves:

Deciduous, alternate, odd-pinnately compound, 6 to 12 inches; stipules persistent, linear-subulate, initially soft, .2 to .5 inch, eventually becoming spines; petiole .35 to .7 inch, hispid; petiolules .04 to .08 inch; stipels needle-like, .08 to .2 inch; pinnae 7-13, opposite or subopposite, blade elliptic, .6 to 2 inches long, .4 to 1.4 inch wide, base rounded, margins entire, apex rounded, lower surfaces pale green, glabrate or sparsely pubescent, upper surfaces green, glabrous.

Flowers:

Inflorescences axillary from lateral buds on old wood, racemes, 4â€“15-flowered, lax; pedicels 4â€“7 mm, stipitate-glandular. Flowers bisexual, bilaterally symmetric; sepals 5, connate, calyx tube campanulate, .2 to .24 inch, pubescent and stipitate-glandular, lobes triangular, .12 to .28 inch, pubescent and stipitate-glandular, apex acuminate; petals 5, pink, banner usually greenish yellow or light yellow in the center, clawed, banner ascending or reflexed, .6 to 1 inch tall, .7 to .8 inch wide, wings projecting, .6 to .8 inch long, .24 to .35 inch wide, keel petals connate distally along abaxial margins, enclosing stamens and pistil, .63 to .8 inch long, .28 to .4 inch wide; stamens 10, diadelphous (9 +1); pistil 1, ovary superior, 1-locular; style .35 to .5 inch, often hispid distally.

Fruit:

Apparently not fruiting in Kansas; legumes, brown to reddish brown, oblong, compressed laterally, 1.2 to 2 inches long, .4 to .5 inch wide, densely hispid, base slightly stipitate, apex apiculate; seeds 3-5, brown, often mottled with purplish-brown spots, reniform, compressed laterally, .2 to .28 inch long, .12 to .14 inch wide, smooth.

Habitat:

Woodlands, roadsides, old farmsteads.

Distribution:

East 1/3 of Kansas

Origin:

Naturalized

Comments:

Robinia hispida is native to the east-central and southeastern United States. In Kansas, it is found primarily around old farmsteads and in disturbed woodlands. It is occasionally planted as an ornamental in urban areas.

Bristly locust flower