Oxytropis lambertii

Oxytropis lambertii Pursh

by Gayle Gratop, Native Plants of Arizona 2007

Common names: Purple locoweed, Lambert’s Locoweed (1), Lambert’s Crazyweed, Colorado Loco, Rock Mountain Loco (2)

Family: Fabaceae (1) (alt. Leguminosae) (3)

Synonymy:

Etymology: Oxytropis means “sharp keel”, referring to the pointed keel petal (3); lambertii named for English botanist Aylmer Bourke Lambert (1761-1842), by Frederick Pursh, who first collected the plant in Kansas in the early 1800’s (4).

Identification

Growth form: Herbaceous perennial, 10 to 40 cm. tall, acaulescent (2).

Roots: Taproot can descend 8ft.

Stem: Subterranean, branchless, flowers and peduncle coming up directly from “cespitose caudex” (5).

Leaves: Gray-green, covered with silvery hairs (1); pinnately compound

(4-20 cm long) with 7-19 leaflets (5), leaflets oblong to linear with entire margins (5-40 mm long) (5).

Inflorescence/flowers: inflorescence in raceme held above leaves (2); purplish to pink and often changing from one to another, white is not uncommon; tubular with 5 lobes (5), two keel petals come to a point (2);.

Fruit: Many seeded, oblong legume (5); sessile, growing directly from the stem (5); erect (2-3 cm long) with a pointed tip (1).

Similar species: There are 26 species of Oxytropis, but no other species occur in northern Arizona (6). There are two species of Oxytropis in Arizona, the other is Oxytropis lambertii var. bigelovii.

Ecology

Life history: Perennial herb (6).

Native/introduced: Native (5).

Photosynthetic pathway:

Phenology: Flowers June to September (1.)

Distribution: In Arizona it is found mostly in the northeastern part of the state, in Apache, Navajo and Coconino counties, but is also found in some counties in southeastern Arizona (6); it has adapted to a broad range of soils (5) and grows from 5,000-8,000ft (2). It is widespread in the Southwest United States and Great Plains from Canada to Texas and to the eastern base of the Rockies in Wyoming and Colorado and over to Utah and Arizona (1);

Uses

One of the most poisonous plants on the western ranges (1). Livestock can become “locoed” if the plant is consumed (5). Loco disease causes loss of vision and paralysis in sheep, cows, horses and other animals. Large amounts must be consumed to be fatal.

References

1. National Audubon Society. 2007. Field Guide to Wildflowers, Western Region. Alfred A. Knopf, Inc. New York, New York.

2. Epple, A.O. 1995. A Field Guide to the Plants of Arizona. Falcon Publishing. Helena, Montana.

3. Hogan, P., Huisinga, K., and Kampe, K. 2005. An Annotated Catalog of the Native and Naturalized Flora of Arizona. Arizona Ethnobotanical Research Association. Flagstaff, Arizona.

4. Charters, M.L. 2007. California Plant Names: Latin and Greek Meanings and Derivations, A Dictionary of Botanical Etymology. (http://www.calflora.net/botanicalnames/index.html. 20, September 2007). Michael R. Charters. Sierra Madre, California.

5. Stubbendieck, J., Hatch, S.L., Butterfield, C.H. 1992. North American Range Plants Fourth Edition. University of Nebraska Press. Lincoln, Nebraska

6. USDA, NCRS.2007. The PLANTS Database (http://plants.usda.gov, 20, September 2007). National Plant Data Center Baton Rouge, Louisiana.

*Oxytropis lambertii Pursh* by Gayle Gratop, Native Plants of Arizona 2007 Common names: Purple locoweed, Lambert’s Locoweed (1), Lambert’s Crazyweed, Colorado Loco, Rock Mountain Loco (2) Family: Fabaceae (1) (alt. Leguminosae) (3) Synonymy: Etymology: Oxytropis means “sharp keel”, referring to the pointed keel petal (3); lambertii named for English botanist Aylmer Bourke Lambert (1761-1842), by Frederick Pursh, who first collected the plant in Kansas in the early 1800’s (4). Identification Growth form: Herbaceous perennial, 10 to 40 cm. tall, acaulescent (2). Roots: Taproot can descend 8ft. Stem: Subterranean, branchless, flowers and peduncle coming up directly from “cespitose caudex” (5). Leaves: Gray-green, covered with silvery hairs (1); pinnately compound (4-20 cm long) with 7-19 leaflets (5), leaflets oblong to linear with entire margins (5-40 mm long) (5). Inflorescence/flowers: inflorescence in raceme held above leaves (2); purplish to pink and often changing from one to another, white is not uncommon; tubular with 5 lobes (5), two keel petals come to a point (2);. Fruit: Many seeded, oblong legume (5); sessile, growing directly from the stem (5); erect (2-3 cm long) with a pointed tip (1). Similar species: There are 26 species of Oxytropis, but no other species occur in northern Arizona (6). There are two species of Oxytropis in Arizona, the other is Oxytropis lambertii var. bigelovii. Ecology Life history: Perennial herb (6). Native/introduced: Native (5). Photosynthetic pathway: Phenology: Flowers June to September (1.) Distribution: In Arizona it is found mostly in the northeastern part of the state, in Apache, Navajo and Coconino counties, but is also found in some counties in southeastern Arizona (6); it has adapted to a broad range of soils (5) and grows from 5,000-8,000ft (2). It is widespread in the Southwest United States and Great Plains from Canada to Texas and to the eastern base of the Rockies in Wyoming and Colorado and over to Utah and Arizona (1); Uses One of the most poisonous plants on the western ranges (1). Livestock can become “locoed” if the plant is consumed (5). Loco disease causes loss of vision and paralysis in sheep, cows, horses and other animals. Large amounts must be consumed to be fatal. References 1. National Audubon Society. 2007. Field Guide to Wildflowers, Western Region. Alfred A. Knopf, Inc. New York, New York. 2. Epple, A.O. 1995. A Field Guide to the Plants of Arizona. Falcon Publishing. Helena, Montana. 3. Hogan, P., Huisinga, K., and Kampe, K. 2005. An Annotated Catalog of the Native and Naturalized Flora of Arizona. Arizona Ethnobotanical Research Association. Flagstaff, Arizona. 4. Charters, M.L. 2007. California Plant Names: Latin and Greek Meanings and Derivations, A Dictionary of Botanical Etymology. (http://www.calflora.net/botanicalnames/index.html. 20, September 2007). Michael R. Charters. Sierra Madre, California. 5. Stubbendieck, J., Hatch, S.L., Butterfield, C.H. 1992. North American Range Plants Fourth Edition. University of Nebraska Press. Lincoln, Nebraska 6. USDA, NCRS.2007. The PLANTS Database (http://plants.usda.gov, 20, September 2007). National Plant Data Center Baton Rouge, Louisiana.