Astragalus whitneyi (Balloon-pod milk-vetch)

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Astragalus whitneyi A. Gray

Balloon-pod milk-vetch, balloon milk-vetch, Whitney's locoweed, Whitney’s locoweed

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Rosidae	Roses, legumes, proteas, dogwoods, hydrangeas, mistletoes, euphorbias, grapes, many more
Order	Fabales	Legumes (pea and bean families)
Family	Fabaceae	Legume family (peas and beans)
Genus	Astragalus	From the Greek astragalos meaning “ankle bone” and an early name applied to some plants in this family because of the shape of the seeds
Species	whitneyi	For Josiah Dwight Whitney (1819-1896), state geologist of California from 1860 to 1876, who made the first geologic study of Yosemite Valley, and for whom Mt. Whitney was named

About plant names...

When I was a kid I read a science fiction story about a crew of astronauts, landing on another planet. I don't remember the details, but they noticed balloons floating in the air, and, upon examination, found they were seedpods, lofted by hydrogen gas made by the host plants. What a clever idea! It never occurred to me that something very similar exists right here on earth. The “balloons” of balloon-pod milkvetch dry out and detach, becoming brittle, and light enough to be blown hither and yon. They collide with rocks and shatter, releasing their seeds. No hydrogen needed!

Balloon-pod milkvetch is native to western North America. It prefers sandy, rocky, or gravelly soil, full sun, and elevations between 2500-12000′ (762-3657 m).

Plants: 1½-16″ (4-40 cm) in height, typically spreading low across the ground.

Leaves: Leaves are green or silvery (due to fine hairs), and bipinnate or tripinnate. Leaves are ⅞-1½″ (2.5-4 cm) in length, and consist of 9-21 leaflets. Each leaflet is oblong to obovate, and ⅛-⅜″ (6-10 mm) long.

Flowers: Dense racemes of 5-20 flowers, each up to ½″ (1.5 cm) long. Flowers are tubular, bell-shaped, and pinkish, lavendar purple, or yellowish, up to ⅜″ (1 cm) long. They appear from May to September.

Fruits: The “balloons” are ⅞-1″ (2.5-3 cm) long, and sort of pear-shaped—if you have seen a lady’s slipper, the shape of the flower is similar. Pods are translucent, with very thin walls, and covered with irregular red-purple blotches, occuring in clusters. The pods are unmistakable.

Online References:

Science.halleyhosting.com

Biology.burke.washington.edu (great photos)

Discover Life

Calscape.org

Calflora

5/3/2018 · Park Blvd., Joshua Tree National Park, California · ≈ 10 × 6″ (24 × 16 cm)

5/3/2018 · Park Blvd., Joshua Tree National Park, California · ≈ 8 × 5″ (20 × 13 cm)

Astragalus whitneyi description by Thomas H. Kent, last updated 25 May 2020.

5/3/2018 · Park Blvd., Joshua Tree National Park, California · ≈ 10 × 6″ (24 × 16 cm)

5/3/2018 · Park Blvd., Joshua Tree National Park, California · ≈ 8 × 5″ (20 × 13 cm)

5/3/2018 · Park Blvd., Joshua Tree National Park, California · ≈ 10 × 6″ (24 × 16 cm)

Range:

About this map...