Psorothamnus emoryi var. emoryi

  • Title

    Psorothamnus emoryi var. emoryi

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Psorothamnus emoryi (A.Gray) Rydb. var. emoryi

  • Description

    6a. Psorothamnus emoryi (Gray) Rydberg var. emoryi

    (Plate VI)

    Suffruticose becoming shrubby, usually white-tomentulose throughout, the stems (rarely the foliage also) occasionally glabrescent or glabrous; stems appearing only sparsely verruculose, the glands mostly concealed by vesture, but becoming prominent in glabrescent forms; terminal leaflet of most leaves 4-16 (20) mm long; spikes nearly always capitate, rarely oblong, (9) 10-13 (15) mm diam at anthesis, the axis (1) 3-11 mm long; calyx as described in key; keel 6-8.5 mm long, the obliquely oblong-obovate blades 4.2-6.2 mm long, (2) 2.2-2.9 mm wide; androecium 6.3-7.8 mm long; 2n = 10 II (Raven, Kyhos & Hill, 1965); n = 10 (Spellenberg, 1973). — Collections: 99 (v.v.).

    Dunes, sandy flats, washes, mostly below 350 m, exceptionally up to 760 m near its n. limit and in Salton Depression down to —35 m, widespread and locally abundant around the n. and w. edges of the Sonoran Desert, from Coachella Valley, Riverside County, California s. to and just beyond the boundary between Baja California Norte and Sur, but not extending w. to the Pacific, e. in California to extreme s.-e. Mohave Desert in s.-e. San Bernardino County (between 29 Palms and Amboy), and to the lower Colorado Valley in e. Riverside and Imperial counties, thence crossing into the lower Gila valley and vicinity in Yuma and w. Pima counties, Arizona and s. in coastal Sonora from the Colorado delta to Puerto Kino and neighboring Isla Tiburon. — Flowering April to June, sometimes again in fall, or in Baja California following rains out of season. —Representative: UNITED STATES. California: San Bernardino: Munz 11,721(NY, POM, SD). Riverside: Parish 4112 (NY, UC), Balls & Everett 23,023 (NY, UC). San Diego: Duran 3181 (NY, UC, WIS); Abrams 3180, 3987 (NY). Imperial: Ferris 7135 (NY); Munz & Hitchcock 12,113 (POM, UC). Arizona. Yuma: Schott (Mex. Bound. Surv.) 237a (NY); Thomber 2399 (UC). Pima: Ora Clark 11,233 (WIS). MEXICO. Sonora: Hastings et al. 62-72 (ARIZ); Whiting 9044 (ARIZ); I. Johnston 3247 (UC). Baia California (Edo.): Wiggins 3023 (UC), 5370 (F, NY); I. Johnston 3344, 4231 (NY, UC); Moran 8172, 8593 (SD), 8673 (NY, SD). Baja California (Sur): Moran 11,621 (NY, SD).

    Psorothamnus emoryi (Gray) Rydb., N. Amer. Fl. 24: 47. 1919, based on Dalea emoryi (William Hemsley Emory, 1811-1887) Gray, Mem. Amer. Acad. II, 5 (Pl. Thurb.): 315. 1854 ("Emoryi"). — "On the desert table-lands of the Gila, June, 1852.— This was first gathered by Colonel Emory...and is the second species mentioned by Dr. Torrey, in Emory’s report, p. 139)." — Holotypus, Thurber 677, from ‘Tablelands, Gila, 18 Apr.’, GH! paratypus, Emory, Nov. 28, 1846, NY (herb. Torr.)! — Parosela emoryi (Gray) A. Hell., Cat. N. Amer. Pl. ed 2, 6. 1900.

    Psorothamnus junceus (rushy, of the stems) Rydb., N. Amer. Fl. 24: 48. 1919. Type collected in the Esperanza Canon, San Pedro Martir Mountains, Lower California, June 27, 1905, Goldman 1178...'-Holotypus, US! clastotypus (fragm.), NY\-Parosela juncea (Rydb.) Standi., Contrib. U. S. Nat. Herb. 23: 462. 1922. Parosela emoryi var. juncea (Rydb.) I. Jtn., Proc. Calif. Acad. Sci. IV, 12: 1047. 1924. Dalea juncea (Rydb.) Wiggins, Contrib. Dudl. Herb. 3(2): 49. 1940.

    At anthesis in late spring and early summer on the floor of the Colorado Desert, var. emoryi is a showy small shrub, often wider than tall, covered all over with countless fluffy balls of rosy-purple flower. Later in the year the foliage disjoints, leaving only a dense tangle of gray interlacing branchlets. North of the border var. emoryi is so densely tomentulose throughout that only a few of the larger orange glands on the stems and peduncles are visible externally, but these are fragile, yielding when bruised a strong-smelling, orange oil. Even in the part of its range lying within California, var. emoryi shows much variation in size of calyx and in proportion of calyx-tube to teeth. These vary from ± 0.8 mm shorter up to ± 1.2 mm longer than the tube as measured from base up to a lateral sinus. Quite typical var. emoryi extends south in Baja California to the latitude of Bahia de los Angeles and Isla Angel de la Guardia, but toward its southern limit the pubescence tends to become thinner, at first on the stems alone, finally throughout the plant. A form with green and glabrous, red-dotted stems (Harbison 41,717, 41,767, SD) but foliage still gray tomentulose, provides passage into the comparatively rare form with hairless leaves described by Rydberg as Psorothamnus junceus. The range of the latter is apparently confined to the east foothills of Sierra San Pedro Martir and adjoining Gulf coastal plain (s. to El Huerfanito in lat. 30° 05' N, Moran 10,349, SD, UC, US). It was maintained provisionally by Wiggins, partly because of its growth-habit, partly because of an unequally toothed calyx. Moran’s collection just cited, however, has the relatively coarse, rigidly zigzag-divaricate branching characteristic of the tomentose form, which, as already noted above, varies greatly in length of calyx-teeth.

    As in other members of sect. Psorothamnus, the petals of Ps. emoryi quickly stain fingers or drying-papers with a purple juice, and the calyces are said (Jaeger, 1940, Desert Wild Flowers 110) to yield a saffron dye used by Indians of the Colorado Desert. Around the mouth of the Colorado River in extreme southeastern California and adjoining Arizona var. emoryi is host to the rafflesiaceous stem-parasite Pilostyles thurberi Gray.