Astragalus hypoxylus is a rare species of flowering plant in the legume family known by the common name Huachuca milkvetch, or Huachuca Mountain milkvetch. It is endemic to Arizona in the United States, where it is known only from the Patagonia and Huachuca Mountains.[1] There are three populations.[2]

Astragalus hypoxylus

Critically Imperiled  (NatureServe)
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fabales
Family: Fabaceae
Subfamily: Faboideae
Genus: Astragalus
Species:
A. hypoxylus
Binomial name
Astragalus hypoxylus

Description

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This small perennial herb forms a patch on the ground no more than about 10 cm (3.9 in) wide and 3 to 4 cm (1.2 to 1.6 in) tall. It grows from a fibrous taproot. The alternately arranged leaves are each made up of several pairs of gray-green leaflets which are a few millimeters[vague] long. The inflorescence is a flower cluster about 1 cm (0.39 in) wide containing tiny white flowers with purple tips. The flowers bloom in April and May and are pollinated by bees of the genera Anthophora, Bombus, and Osmia. The fruit is a yellow and purple legume pod about 1 cm (0.39 in). This Astragalus looks so different from other species that it was once classified in a monotypic genus all its own.[1]

This plant grows in woodlands dominated by Emory oak (Quercus emoryi), Mexican blue oak (Q. oblongifolia), alligator juniper (Juniperus deppeana), and Mexican pinyon (Pinus discolor). The substrate is a gravelly soil rich in limestone and metamorphic rock.[1][3]

References

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  1. ^ a b c Astragalus hypoxylus. The Nature Conservancy.
  2. ^ Astragalus hypoxylus Archived October 26, 2011, at the Wayback Machine. Center for Plant Conservation.
  3. ^ "USDA Plants Database".
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