(Benth.) G.L.Nesom
Description
Erythranthe nepalensis is a small wetland herb of temperate East and South Asia, recorded from Japan, China, Korea, Taiwan, Nepal, Bhutan, India, Myanmar, Pakistan and Bhutan, with around 2199 georeferenced occurrences in GBIF. It grows in damp, open ground: stream banks, ditch margins, wet meadows, seepages, rice-field bunds and moist rock crevices from the foothills into the temperate montane zone. The photographed plant from Thimphu in Bhutan at 2600 m in May is characteristic of such cool, moist Himalayan habitats, where it flowers in spring along watercourses and on dripping banks.
It is a slender annual or short-lived perennial herb with weak, decumbent to ascending, often rooting stems forming low mats. The leaves are opposite, small, ovate to broadly ovate, palmately veined, with a few shallow teeth and short petioles. The flowers are solitary in the leaf axils on slender pedicels; the calyx is tubular-campanulate and angled-ribbed, with short triangular lobes, and the corolla is bilabiate and yellow, the throat marked with reddish-brown to purplish spots and the lower lip prominent. There are four didynamous stamens, and the fruit is an oblong capsule enclosed by the persistent ribbed calyx, releasing numerous tiny seeds.
Formerly placed in Mimulus (as Mimulus tenellus var. nepalensis), the species was transferred to Erythranthe by G.L. Nesom following the molecular recircumscription that divided the old Mimulus among several genera and moved them from Scrophulariaceae to Phrymaceae. The spotted, bilabiate yellow flowers are adapted to bee pollination, and the plant's affinity for moist, disturbed ground allows ready local colonisation. Common and widespread across its range, it is of no particular conservation concern.
Author: (Benth.) G.L.Nesom · Sources: POWO (Kew), GBIF, Flora of China Vol. 18, Flora of Bhutan Vol. 2, Flora of Nepal, Taxonomy of Erythranthe (Phrymaceae) (Nesom)