Loco Weed

Physical Description:
Gray. Stems slender, widely spreading or prostrate, 3 to 4 feet long; herbage rather sparsely appressed-pubescent or the stems and upper surface of the leaves glabrate; leaves 3 to 5/12 inches long; leaflets 15 to 31, narrowly oblong or linear, obtuse, 3 to 8 lines long; peduncles 2 to 7 inches long, divaricately or widely spreading, surpassing the leaves; spikes short or capitate, crowded; equally crowded in fruit (3/4 to 1 3/4 inches long); flowers 3 to 4 lines long; calyx-teeth subulate, about as long as the campanulate tube; corolla yellowish-white; pods broadly ovate, acuminate, straight, 1-celled, 5 lines long, densely white-pilose when young, less conspicuously so when mature, 6 to 15-seeded.

Location:
Alkaline valley flats and plains, 400 to 1100 feet: upper San Joaquin Valley in Kern County; San Bernadino Valley. Lower California. Oct.

Field Note:
This plant is considered poisonous to sheep. In the San Bernadino Valley it is now exterminated by cultivation according to a note by Parish in 1914. In 1873 it (with A. lentiginosus) was said to prevail quite abundantly over an area of 150 square miles in the upper San Joaquin Valley (U.S. Dept. Agr. Rep. 1874:159). A. hornii is still common in the Bakersfield region. We have no records from the Mohave Desert. The printed heading on the label of the type spm. of A. hornii (Gray Herb.) reads "Owens Valley and Fort Tejon", but there is no evidence that it occurs in the Owens Valley (as stated in Bot. Cal. 1:150), although it does occur in the Fort Tejon region.

Locations:
San Bernadino, Parish 2004; Bakersfield, Leckenby.

Variation:
tulatensis Jepson - comb. n. Herbage more pubescent; leaflets smaller and fewer, 13 to 17, the uppermost at least linear-oblong or oblanceolate; peduncles slender, 2 to 3 inches long; racemes 1/2 to 1 inch long; flowers 3 1/2 lines long; pods smaller. -- Upper San Joaquin Valley in Kern and Tulare Cos.: Bakersfield, Hall 8343.

References:
Astragalus Hornii Gray, Proc. Am. Acad. 7:398 (1868), type loc. Ft. Tejon, Horn; Parish, Zoe 3:103 (1890); Jepson, Man. 567, fig 556 (1925). Phaca hornii Rydb. N. Am. Fl. 24:358 (1929). Var. tularensis Jepson. Phaca tularensis Rydb. N. Am. Fl. 24:358 (1929), type loc. near Tulare Lake, Lemmon.

Reference: A Flora of California Volume 2, Willis Linn Jepson, September 1936 (The Jepson Herbarium)