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Astragalus anxius
Astragalus anxius R.J. Meinke & Kaye
Troubled Milkvetch
Fabaceae (Pea family)
Synonym(s): Astragalus tegetarioides var. anxius
USDA Symbol: ASAN18
USDA Native Status: L48 (N)
"Decumbent to weakly prostrate perennial; stems slender, trailing, few to many, 0.3-2.0 dm long, freely branching beginning with the lower nodes, arising from a weak, suffruticulose caudex; roots diffuse, taproot short with proliferous secondary and tertiary roots, these spreading horizontally in the loose, shallow substrate, with larger plants ultimately developing densely branched clusters or mats of pubescent, capillary rootlets up to 10 cm across, possibly with mycorrhizal connections, forming nodules; pubescence of short semi-appressed hairs on the lower stems, hoary to subvillous on the new growth, becoming loosely villous with numerous straight to sinuous hairs up to 1.2 mm long on the stipules, petioles, and particularly the leaflets, the latter pilosulous below and glabrous and green above, occasionally with scattered hairs 1-2 mm inside the dorsal margin." (reslit: 2899).
"The epithet "anxius" has both passive and active meanings, i.e., troubled or troublesome. Considering the probable correlation be- tween public lands grazing and the long-term prospects for this po- tentially endangered species, either common name may be appro- priate, depending on the point of view." (reslit: 2899).
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Plant Characteristics
Duration: PerennialHabit: Herb
Leaf Arrangement: Alternate
Fruit Type: Legume
Size Notes: "Stems slender, trailing, few to many, 0.3-2.0 dm long." (reslit: 2899).
Leaf: "Stipules 1-4 mm long, thinly herbaceous, becoming papery with age, ovate-acuminate to lanceolate, the blades mostly recurved at the tip, generally completely free but occasionally more or less amplexicaul and weakly united by a stipular line at the lowest nodes; leaves 2.0-5.0 (-7.0) cm long, with filiform petiole approximately equalling the blade, leaflets crowded, sessile to obscurely petiolulate, 9-13(- 1 5) per leaf, (2.5-)4-9(-12) mm long, (1.5-)2.5-7.0(-10.5) mm wide, flat or partially folded, obovate-cuneate, obtuse to truncate or with a slight apical notch." (reslit: 2899).
Flower: "Peduncles slender, spreading to erect, 0.5-3.5 cm long, shorter than the leaf; racemes congested, 0.8-2.2 cm long in flower, with 0.5-2.0 mm spacing between pedicels, the (7-)9-13(-15) flowers spreading to ascending, usually declined in post-anthesis; floral bracts herbaceous, lance-linear, 1-3 mm long, ciliate; pedicels slender, ascending to arcuate, 0.5-1.5 mm long; calyx 3.2-4.7(-5.0) mm long, the tube 1.5-2.2 mm long, pubescence spreading, with straight to wavy hairs 0.7-1.1 mm long, the subulate teeth ciliate, 1.7-2.7 mm long; corolla dull lavender in bud, purple and white at anthesis; banner rose-purple to deep lilac when fresh, often with darker striations and a pale eye at the base, drying deep violet in well-preserved specimens, narrowly obovate-cuneate, 6.5-10.0(-12.0) mm long, 3.0-5.5(-6.5) mm wide, the blade reflexed 60-80 degrees, notched at the apex, the claw 2.0-3.5 mm long; wings white, drying white to faintly lilac, 1.5-3.0 mm shorter than the banner, 4.5-8.8 mm long, more or less asymmetric, frequently bent or sigmoidally twisted to the right, the blades narrowly oblong to ligulate, obtuse, 3.8-6.8 mm long, the claws 1.7-2.1 mm long; keel pale lilac proximally and dark purple at the tip, 4.7-6.6 mm long, the claws 1.5-2.2 mm long, the oblong blades 3.3-4.4 mm long, incurved ca. 100 degrees at the broad, deltoid apex; anthers 0.20-0.30 mm long, pollen orange." (reslit: 2899).
Fruit: "Pod spreading to declined, sessile, dehiscent from the receptacle, uniloculate, lenticulate, 3.5-4.5 mm long, 3.2-4.2 mm wide, plumply ovoid to weakly compressed laterally in cross-section, the papery valves silky-villous, not inflexed, usually glabrescent with age, revealing thin cross-reticulations, beakless or with beak less than 0.5 mm, style persistent, ovules 2-3(-4); seeds (1-)2- 3, dull black, smooth, 1.7- 2.1 mm long. Astragalus anxius is largely in fruit by late July." (reslit: 2899).
Bloom Information
Bloom Color: White , Purple , VioletBloom Time: May , Jun , Jul
Bloom Notes: "Corolla dull lavender in bud, purple and white at anthesis; banner rose-purple to deep lilac when fresh, often with darker striations and a pale eye at the base, drying deep violet in well-preserved specimens." (reslit: 2899).
Distribution
USA: CANative Distribution: "Astragalus anxius is believed to be endemic to Ash Valley in extreme north-central Lassen County, California." (reslit: 2899).
Native Habitat: "At 1,540-1,660 meters elevation. The species is scattered sporadically over a few square kilometers northwest of Spooner Reservoir, occurring on arid flats in or near juniper-sagebrush steppe or Pinus jeffreyi woodland. Common associate species include Artemisia tridentata, Juniperus occidentalis, Eriogonum prociduum, Phacelia bastata, Mentzelia albicaulis, Ipomopsis congesta, Senecio ?anus, Ivesia paniculata, Ranunculus testiculatus, Alyssum alyssoides, Sisymbrium altissimum, and Bromus tectorum." (reslit: 2899).
Web Reference
Webref 30 - Calflora (2018) CalfloraWebref 36 - Jepson eFlora (2019) The Jepson Herbarium, University of California, Berkeley
Webref 23 - Southwest Environmental Information Network (2009) SEINet - Arizona Chapter
Research Literature
Reslit 2899 - TAXONOMIC ASSESSMENT OF ASTRAGALUS TEGETARIOIDES (FABACEAE) AND A NEW RELATED SPECIES FROM NORTHERN CALIFORNIA (1992) Robert J. Meinke and Thomas N. KayeThis information was provided by the Florida WIldflower Foundation.
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Additional resources
USDA: Find Astragalus anxius in USDA PlantsFNA: Find Astragalus anxius in the Flora of North America (if available)
Google: Search Google for Astragalus anxius
Metadata
Record Modified: 2023-06-20Research By: Joseph A. Marcus