Carnegiea gigantea, Giant Saguaro

Southwest Desert Flora

Home to the plants of the Sonoran, Chihuahuan and Mojave Deserts

Cirsium ochrocentrum, Yellowspine Thistle

Phaseolus angustissimus, Slimleaf Bean

Slimleaf Bean flowers are purple, pink or lavender. The flowers are typical “pea” type flowers and the “keel” petal is noticeably twisted or curved as shown in the photo. Phaseolus angustissimus Slimleaf Bean flowers blooms from May to October. Fruits are formed shortly thereafter. The fruits are narrow flat seed pods, curved or half-moon shaped up to 3 inches (76 mm) long. Phaseolus angustissimus Slimleaf Bean is a native perennial that grows up to 10 inches (25.4 cm) high is very similar in appearance to Slimjim Bean. Phaseolus angustissimus Slimleaf Bean has pinnately compound dark green leaves. The leaves alternate along a twining vine and vary in shape but generally linear-lanceolate leaflets or oblong-lanceolate leaflets.  Phaseolus angustissimus Slimleaf Bean preferred habitats include mesas often growing within trees and shrubs; elevations from 3,500 to 7,500 feet (1,066 to 2,285 m). They are found in the southwestern United States in AZ, NM and TX.  Phaseolus angustissimus

Scientific Name: Phaseolus angustissimus
Common Name: Slimleaf Bean

Also Called: Narrowleaf Bean, Narrow-Leaflet Bean

Family: Fabaceae or Leguminosae Family

Synonyms: (Phaseolus angustissimus var. latus)

Status: Native

Duration: Perennial

Size: Up to 10 inches (25 cm) high and trailing along up to 3 feet (.91 m) or more.

Growth Form: Slimleaf Bean is a forb/herb and a vine, the stems are slender and branched and the plants are trailing and/or twining; the plants have a thick woody taproot.

Leaves: Slimleaf Bean has dark green leaves that are pinnately compound, the 3 leaflets are narrow and pointed.

Flower Color: Slimleaf Bean has purple, magenta, pink or lavender flowers, 2 to 5 flowers on a long blooming stalk, the fruit is a narrow curved flat seed pod with 2 or more seeds.

Flowering Season: May to October

Elevation: 3,500 to 7,500 feet (1,066 to 2,285 m).

Habitat Preferences: Slimleaf Bean prefers mesas and are often growing within trees and shrubs as well as along rocky hillsides; at mid- to -higher elevations Slimleaf Bean may be found in grasslands, pinyon/juniper communities and forested areas.

Recorded Range: Slimleaf Bean is found in the southwestern United States in Arizona, New Mexico and Texas. It is also native to northern Sonora, Mexico.

North America & US County Distribution Map for Phaseolus angustissimus.

North America species range map for Slimleaf Bean, Phaseolus angustissimus:

North America species range map for Slimleaf Bean, Phaseolus angustissimus:
Click image for full size map.

U.S. Weed Information: Unknown
Invasive/Noxious Weed Information: Unknown
Wetland Indicator: Unknown
Threatened/Endangered Information: Unknown

Genus Information: In North America, USDA Plants Database lists 12 species and 6 accepted taxa overall for Phaseolus. Worldwide, World Flora Online includes 187 accepted species names and a further 21 scientific names of infraspecific rank for the genus.

The genus Phaseolus was published in 1753 by Carl Linnaeus, (1707-1778).

In the Southwestern United States: Arizona has 7 species of Phaseolus, California and Utah each have 1 species, Nevada has 0 species, New Mexico has 6 species and Texas has 8 species. Data approximate, subject to revision.

Comments: Slimleaf Bean is a very close relative of the cultivated and wild Tepary Bean, Phaseolus acutifolius. It is interesting that the wild Tepary Bean also grows in Arizona, New Mexico and Texas and throughout Mexico.

The Arizona type species for Phaseolus angustissimus (recognized as variety latus), was collected along the Little Colorado River near Winslow, Navajo County (Jones, 1980). Unlike similar plants of the same genus, Slimleaf Bean may be differentiated by the fact that it is a perennial plant from woody rootstock.

In Southwest Desert Flora also see Slimjim Bean, Phaseolus filiformis.

Importance to Wildlife, Birds and Livestock
Slimleaf Bean, Phaseolus angustissimus has attractive flowers, the flowers and their seeds may be visited by hummingbirds and/or small mammals including rodents and granivorous birds in search of nectar or food.

Beneficial Value to Butterflies, Honey Bees and Insects
Slimleaf Bean, Phaseolus angustissimus has attractive flowers, the flowers and their plants may be visited by butterflies, moths, flies, honeybees, Native Bees and other insects in search of food and nectar.

Etymology:
The genus “Phaseolus” is from the Ancient Greek word "phaselus" meaning a kind of bean with an edible pod.

The genus Phaseolus was published in 1753 by Carl Linnaeus, (1707-1778).

The species epithet angustissimus (angustis'simus:) means very narrow, a reference to the leaves which are very narrow.

The taxon Phaseolus angustissimus was described in 1853 by Asa Gray, (1810-1888).

Ethnobotany - Native American Ethnobotany; University of Michigan - Dearborn
Slimleaf Bean, Phaseolus angustissimus is used by southwestern United States indigenous peoples for such purposes described below.
  • Zuni Drug, Pediatric Aid, Crushed leaves, blossoms and powdered root rubbed on a child's body as a strengthener. When an infant boy showed signs of timidity, his father carried a small quantity of corn meal wrapped in a bit of corn husk to the warrior of his choice, presented it and asked that the warrior apply the medicine on his child's body so that he may have a brave heart and never be afraid of the enemy. The warrior then chewed the crushed leaves and blossoms and the powdered root, ejected the mass into his hands and rubbed it all over the child's body.

  • Zuni Drug, Strengthener, Crushed leaves, blossoms and powdered root rubbed on a child's body as a strengthener. When an infant boy showed signs of timidity, his father carried a small quantity of corn meal wrapped in a bit of corn husk to the warrior of his choice, presented it and asked that the warrior apply the medicine on his child's body so that he may have a brave heart and never be afraid of the enemy. The warrior then chewed the crushed leaves and blossoms and the powdered root, ejected the mass into his hands and rubbed it all over the child's body.

  • See complete listing of ethno-botanical uses at Native American Ethnobotany, University of Michigan, Dearborn.

    Date Profile Completed: 11/15/2019 updated 02/23/2022
    References and additional information:
    Kearney, Thomas H., Peebles, Robert H., 1960, Arizona Flora, University of California Press, Berkley and Los Angeles, California.
    Plants.USDA.gov; Department of Agriculture, Natural Resources Conservation Service on-line database and USGS ITIS search; accessed on-line; 02/23/2022.
    https://plants.usda.gov/home/basicSearchResults?resultId=274799e7-293d-4e0a-8c1b-18f824ce98ff
    https://plants.usda.gov/home/plantProfile?symbol=PHAN3
    World Flora Online; A Project of the World Flora Online Consortium; An Online Flora of All Known Plants - (accessed on-line; 02/23/2022)
    http://www.worldfloraonline.org/search?query=phaseolus
    Kearney and Peebles 1969, McDougall 1973, Allred and Ivey 2012, Heil et al. 2013; Editors: L.Crumbacher 2011, F.S.Coburn 2015, A.Hazelton 2017; from SEINet Field Guide, on-line; accessed 02/23/2022.
    https://swbiodiversity.org/seinet/taxa/index.php?taxon=1418&clid=3
    Dr. David Bogler, Missouri Botanical Garden; Encyclopedia of Life, Slimleaf Bean, Phaseolus angustissimus - (accessed on-line 02/23/2022).
    https://eol.org/pages/640457/articles
    Wikipedia contributors. "Phaseolus angustissimus." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 11 Mar. 2021. Web. 23 Feb. 2022.
    Jeff Schalau, County Director, Agent, Agriculture and Natural Resources, University of Arizona Cooperative Extension, online at Yavapai County; Yavapai County Native & Naturalized Plants; Phaseolus angustissimus - slimleaf bean; (accessed online: 02/22/2022)
    https://cals.arizona.edu/yavapaiplants/SpeciesDetailForb.php?genus=Phaseolus&species=angustissimus
    Wolf, M. 2018. Plant Guide for tepary bean (Phaseolus acutifolius). USDA-Natural Resources Conservation Service, Tucson Plant Materials Center. Tucson, AZ 85705. - (accessed on-line 02/23/2022).
    Seiler, John, Peterson, John, North American species range map courtesy of Virginia Tech, Dept. of Forest Resources & Environmental Conservation
    http://dendro.cnre.vt.edu/dendrology/
    SEINet synonyms, scientific names, geographic locations, general information.
    http://swbiodiversity.org/seinet/
    Etymology: Michael L. Charters California Plant Names: Latin and Greek Meanings and Derivations; A Dictionary of Botanical and Biographical Etymology - (accessed on-line; 02/23/2022)
    http://www.calflora.net/botanicalnames/pageAN-AZ.html
    IPNI (2020). International Plant Names Index. Published on the Internet http://www.ipni.org, The Royal Botanic Gardens, Kew, Harvard University Herbaria & Libraries and Australian National Botanic Gardens. [Retrieved on-line; 23 February 2022].
    https://www.ipni.org/?q=phaseolus
    https://www.ipni.org/?page=2&q=phaseolus