File:Limestone monkeyflower, Erythranthe calcicola (44561385370).jpg

limestone monkeyflower, Erythranthe calcicola, California, White Mountains, Deep Springs Valley drainage, elevation 1917 m (6290 ft).

Limestone monkeyflower is a recently recognized regional endemic, limited to the northern Mojave Desert and southwestern Great Basin Desert of southeast Mono and eastern Inyo counties in California, and Esmeralda, southern Nye, and western Clark counties in Nevada. As its name reflects, it seems to be found only on rocky soils and slopes with a strong carbonate component, which happen to be very common soils within its limited geographic range. The species has been found at elevations of 915-2165 meters (3000-7100 feet).

The species usually appears only after the wettest winters in the desert, and 2017 was one of the wettest on record in this area. So much so that individuals were defying the typical short and compact habit of this species and developing tall elongated stems much resembling those of redstem monkeyflower (Erythranthe rubella).

Limestone monkeyflower was recognized as a distinct species by Naomi Fraga in 2012, after having been confused with Erythranthe (=Mimulus) montioides since its earliest collections in 1937. Its closest relative actually appears to be Erythranthe rubella, from which it differs in having calyces straight and broadly cylindric to slightly flared while in flower (vs narrowly cylindric and curved), flowers always yellow or rarely white (never magenta), largest flowers 5-9 mm across (vs 3-5 mm) with longitudinal maroon streaks (vs exclusively round or transverse spots) in the throat, styles included (vs shortly exserted), and leaves with stalked glands (vs sessile glands) and broader on average.