Trifolium jokerstii (Leguminosae, Papilionoideae), a new species from Butte County, California

Trifolium jokerstii (Leguminosae, Papilionoideae), a new species from Butte County, California, is described and illustrated. It is morphologically similar to T barbigerum and T grayi, from which it differs in stipule shape, flower color, seed size, and lack of pubescence. The genus Trifolium (Leguminosae, Papilionoideae) consists of approximately 240 species found in mainly temperate and montane regions, with areas of "Mediterranean" climate (the Mediterranean basin, California, and Chile) being considered centers of diversity in the genus (Zohary & Heller, 1984). In North America, 93 species are known (Kartesz, 1994), of which 64 are native and 29 are introductions. Isely (1993) recognized 45 species in California, 32 of which are native to the state; of these, 14 belong to section Involucrarium, a New World endemic section characterized by the presence of an involucre of fused bracts subtending the inflorescence. During the course of a revision of Trifolium barbigerum Torrey and related species of section Involucrarium, several specimens from the vicinity of North Table Mountain, Oroville, Butte County, in north-central California, were determined to represent an undescribed species. A single collection was examined by Isely and mentioned in his treatment of the genus for the Jepson Manual as a yellow-flowered variant of Trifolium barbigerum var. andrewsii A. Gray (Isely, 1993). The new species was also mentioned by Oswald and Ahart (1994) as possibly the same variety, with a comment that the plants might deserve taxonomic recognition. No collections of this taxon were mentioned by McDermott (1910) or Zohary and Heller (1984) in their monographs of the genus. The species is significantly different from both T barbigerum and IT grayi Lojacono (T barbigerum var. andrewsii A. Gray) and is described here as new. Trifolium jokerstii Vincent & R. Morgan, sp. nov. TYPE: U.S.A. California: Butte County, North Table Mountain, N of Oroville, 29 Mar. 1996, M. A. Vincent 7227, Rhode & Snowden (holotype, MU 177695; isotypes, F, ISC, MO, NY, RSA, UC, US). Figure 1. Trifolium annuum, caulis erectis vel ascendenti et simplico vel ramoso, glabro; stipulis ovatis, serratis, persistentibus; foliolis ellipticis vel obovatis, serrulatis; capitulis semiglobosis; pedunculis foliis longioribus; involucris lobtis: lobis ovatis, dentatis; calycibus campanulatis, pubescentibus, tenuis: lobis simplicibus subulatis, plumosis; corollis luteis ad sulphureas. Affinis T barbigero Torrey et T grayi Lojacono; ab utroque caulibus et foliis glabris, stipulis ovatis, serratis, corollis luteis ad sulphureas, et seminibus 3.1-3.4 mm longis differt. Erect-ascending annual with simple to branched glabrous stems to 20 cm, from a fibrous taproot. Stipules thin, pale to green, 8-13(-20) x 7-10 mm, rounded to acute and serrate at apex, persistent, adnate to the petiole, distinct or sometimes basally fused into a cylinder for 2/3 their length. Leaves trifoliolate, petioles to 90 mm, glabrous. Leaflets sessile, glabrous, serrulate to rarely nearly lobed, elliptic to obovate, (5-)8-17(-32) X (4-)68(-15) mm, with or without a prominent white to dark purple chevron. Inflorescence involucrate, subglobose, 10-30-flowered, 12-30 mm wide, peduncle longer than the leaves; involucre wide-campanulate to nearly flat, (13-)15-17(-22) mm wide, glabrous, lobed, the lobes rounded, toothed. Calyx 7-9 mm long, expanding in fruit, tube membranous, sparingly pubescent, campanulate, 5-nerved, oblique; teeth plumose, nearly as long as to slightly longer than tube, subulate-setaceous, the upper shorter than the lower, simple, lateral teeth simple to bifid, lower tooth bifid to trifid. Corolla 10-15 mm long, golden-yellow to sulphur-yellow; standard broadly ovate, inflated in fruit with a constricted throat above the mouth of the calyx; wings auriculate, longer than keel; keel with or without a purple spot on each side. Ovary glabrous, 4-5 mm NovoN 8: 91-93. 1998. This content downloaded from 157.55.39.17 on Fri, 02 Sep 2016 06:06:29 UTC All use subject to http://about.jstor.org/terms