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Psorothamnus arborescens var. arborescens

Higher Taxonomy
Family: Fabaceae (Leguminosae)View DescriptionDichotomous Key

Habit: Annual to tree. Leaf: generally alternate, generally compound, generally stipuled, generally entire, pinnately veined Inflorescence: generally raceme, spike, umbel or head; or flowers 1--few in axils. Flower: generally bisexual, generally bilateral; hypanthium 0 or flat to tubular; sepals generally 5, generally fused; petals generally 5, free, fused, or lower 2 +- united into keel (see 3, Key to Groups, for banner, wings); stamens 10 or many (or [1], 5, 6, 7, 9), free or fused or 10 with 9 filaments at least partly fused, 1 (uppermost) free; pistil 1, ovary superior, generally 1-chambered, ovules 1--many, style, stigma 1. Fruit: legume, including a stalk-like base (above receptacle) or not. Seed: 1--many, often +- reniform, generally hard, smooth.
Genera In Family: +- 730 genera, 19400 species: worldwide; with grasses, requisite in agriculture, most natural ecosystems. Many cultivated, most importantly Arachis, peanut; Glycine, soybean; Phaseolus, beans; Medicago, alfalfa; Trifolium, clovers; many orns. Note: Unless stated otherwise, fruit length including stalk-like base, number of 2° leaflets is per 1° leaflet. Upper suture of fruit adaxial, lower abaxial. Anthyllis vulneraria L. evidently a waif, a contaminant of legume seed from Europe. Laburnum anagyroides Medik., collected on Mount St. Helena in 1987, may be naturalized. Ceratonia siliqua L., carob tree (Group 2), differs from Gleditsia triacanthos L. in having evergreen (vs deciduous) leaves that are 1-pinnate (vs 1-pinnate on spurs on old stems, 2-pinnate on new stems) with 2--5(8) (vs 7--17) 1° leaflets, commonly cultivated, now naturalized in southern California. Aeschynomene rudis Benth. , Halimodendron halodendron (Pall.) Voss (possibly extirpated), Lens culinaris Medik. are agricultural weeds. Caragana arborescens Lam. only cult. Ononis alopecuroides L. , Sphaerophysa salsula (Pall.) DC. all evidently extirpated. Cercidium moved to Parkinsonia; Chamaecytisus to Cytisus; Psoralidium lanceolatum to Ladeania.
eFlora Treatment Author: Martin F. Wojciechowski, except as noted
Scientific Editor: Martin F. Wojciechowski, Thomas J. Rosatti.
Genus: PsorothamnusView DescriptionDichotomous Key

Common Name: INDIGO-BUSH
Habit: Perennial herb to small tree, generally thorny, gland-dotted, especially stems, generally hairy. Stem: generally intricately branched. Leaf: simple or generally odd-1-pinnate, leaflets 1--3, generally more. Inflorescence: axillary or terminal, raceme, spike- or head-like or not; pedicel bractlets (0)2. Flower: calyx lobes generally unequal, upper 2 often largest; petals from receptacle, indigo blue to pink-purple; stamens 10, filaments partly fused; ovules generally 2. Fruit: indehiscent, included in or exserted from calyx, generally glandular. Seed: 1.
Species In Genus: 9 species: deserts of southwestern United States, Mexico, basins of Colorado Plateau. Etymology: (Greek: scabshrub)
eFlora Treatment Author: Martin F. Wojciechowski & Duane Isely
Species: Psorothamnus arborescensView Description 

Habit: Shrub < 1 m, armed or not, glabrous to +- puberulent. Leaf: leaflets generally 5--7, 3--14 mm, terminal (occasionally all) often continuous with axis. Inflorescence: raceme, open; pedicel bractlets 2. Flower: calyx lobes +- equal, generally < tube; corolla 6--10 mm, indigo-blue to violet-purple, glands 0. Fruit: exserted, 7--10 mm, ovoid-ellipsoid, hairs 0 to fine, glands few to several, scattered, large, +- yellow.
Note: Possibly best united with Psorothamnus fremontii; varieties similar morphologically, distinct geographically.

Psorothamnus arborescens (A. Gray) Barneby var. arborescens
Leaf: leaflets lanceolate to ovate, larger 2.5 mm or more wide, terminal often continuous with axis. Flower: calyx 7--9 mm, sparsely to densely hairy.
Ecology: Desert; Elevation: 400--800 m. Bioregional Distribution: sw DMoj (Kern, San Bernardino cos.); Distribution Outside California: Mexico. Flowering Time: Apr--May
Synonyms: Dalea arborescens Torr. ex A. Gray; Dalea fremontii Torr. ex A. Gray var. saundersii (Parish) Munz; Psorodendron arborescens (Torr. ex A. Gray) Rydb.
eFlora Treatment Author: Martin F. Wojciechowski & Duane Isely
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Listed on CNPS Rare Plant Inventory

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botanical illustration including Psorothamnus arborescens var. arborescens


Citation for this treatment: Martin F. Wojciechowski & Duane Isely 2017. Psorothamnus arborescens var. arborescens, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on October 20, 2017.

Citation for the whole project: Jepson Flora Project (eds.) 2017. Jepson eFlora,, accessed on October 20, 2017.

Psorothamnus arborescens var. arborescens
click for enlargement
© 2013 Neal Kramer
Psorothamnus arborescens var. arborescens
click for enlargement
© 2013 Neal Kramer
Psorothamnus arborescens var. arborescens
click for enlargement
© 2013 Neal Kramer
Psorothamnus arborescens var. arborescens
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© 2013 Lech Naumovich
Psorothamnus arborescens var. arborescens
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© 1997 Christopher L. Christie
Psorothamnus arborescens var. arborescens
click for enlargement
© 2013 Neal Kramer

More photos of Psorothamnus arborescens var. arborescens in CalPhotos

Geographic subdivisions for Psorothamnus arborescens var. arborescens:
sw DMoj (Kern, San Bernardino cos.);
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.