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
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.