Two Lesquerellas (Cruciferae) of South Central and Western Montana

Abstract

Two heretofore unknown species of Lesquerella are described. These occur in limited areas in the mountains of central and western Montana. Both species, here named L. lesicii and L. pulchella, occur in patches of limestone-derived soils and rubble that are conspicuously barren of trees and shrubs and other types of plant cover, or on the borders of such areas where the limestone detritus meets soils and rubble of crystalline rocks. Also, they are often found in open areas in sparse stands of low-growing trees or shrubs. Recent samplings of populations of Lesquerella in Montana show that species diversity in this genus goes somewhat beyond that previously recognized in monographic treatments (Payson, 1922; Rollins & Shaw, 1973; Rollins, 1993). What has been known for the area is that species of Lesquerella are often abundant and are an important component of the flora of specialized habitats, especially where limestone or derivatives of limestone are involved. The nature of some of these habitats is well shown in Figures 1 and 2, where the highly reflective limestone-derived soil and rubble contrast with the more vegetated surrounding areas. These windswept whitish areas are the places where L. pulchella grows. Also known is that a high degree of complexity exists within some species, such as L. alpina (Nuttall ex Torrey & A. Gray) S. Watson, which is frequently encountered in the general region. But now we see that there are existing taxa not previously recognized, and these have complicated relationships with species south of Montana in Idaho and Wyoming. The main purpose of this paper is to describe two new species of Lesquerella and explain their relationships to previously known taxa. It is somewhat ironic that I had only recently (Rollins, 1993) completed a review of Lesquerella as it occurs in North America when these two species showed up too late to be included in my treatment. Lesquerella lesicii Rollins, sp. nov. TYPE: U.S.A. Montana: abundant in gravelly limestone-derived soil at edge of limber pine woodland on the ridge W of Layout Creek, '/ mi. S of Mystery Cave, Pryor Mountains, Carbon County, 7500 ft., T85, R28 E, S21, SW '4, with Shoshonea pulvinata, Astragalus aretoides, and A. miser, 20 June 1992, Peter Lesica 5707 and Rob DeVelica (holotype, GH). Herba perennis, caudicibus simnplicibus, folia basibus erectis dense stellatis argenteis 0.5-1 cm longis, caulis erectis vel decumbentibus gracilibus 1-1.5 dm longis, petalis aureis spathulatis vel lingulatis 6-7 mm longis, pedicellis fructiferis recurvatis vel divaricatis 5-10 mm longis, siliquis globosis vel subglobosis 3-4 mm diametro pilis stellatis adspersus, loculis 3-5 ovulatis. Delicate perennial; caudex simple, sometimes elongated and with old leaf bases; basal leaves erect, usually fewer than 10, entire, 1.5-3 cm long, petioles slender, abruptly expanded to blade, 1-2.5 cm long, blades broadly ovate to elliptical, 0.5-1 cm long, silvery from a dense cover of stellate trichomes; leaf trichomes small, ca. 0.02 mm diam., ray tips 15-25, each primary ray forked near its base; flowering stems very slender, mostly filiform, simple, erect to decumbent, 1-1.5 dm long; cauline leaves few, remote, ? spatulate, lower somewhat petiolate, upper cuneate at base; inflorescences lax, rarely nodding, usually with fewer than 10 flowers; sepals erect, densely pubescent, oblong, nonsaccate and without scarious margins, 3.5-4 mm long; petals yellow, often fading to light purple toward their tips, spatulate to nearly lingulate, 6-7 mm long; stamens strongly tetradynymous; infructescences lax, greatly elongated; fruiting pedicels filiform, recurved in a single arch to widely spreading, 5-10 mm long; siliques globose or subglobose, spreading at right angles to rachis to pendent, 3-4 mm diam., + densely pubescent on exterior, valves glabrous on the interior; styles ca. 1.5 mm long, glabrous or NovoN 5: 71-75. 1995. This content downloaded from 207.46.13.38 on Fri, 20 May 2016 08:54:19 UTC All use subject to http://about.jstor.org/terms