Previously, Mimulus (Erythranthe) microphyllus
was referred to as the "inland annual race of Mimulus guttatus
" Nelson 2013
. It lacks rhizomes, previously thought to represent variation in environmental factors. However, now M. guttatus
has been split taxonomically (Nesom 2012), with the annual plants recognized as a separate species.
Flowers as well as plants are highly variable in size (Nesom 2012). Nesom (2012) says: "Erythranthe microphylla is characterized by its annual duration (fibrous-rooted), usually simple stems, relatively widely spaced leaves, glabrous to hirtellous vestiture, open corollas, and calyces closing at the throat. Even in the smallest corollas, the stigma is positioned above the upper anther pair, indicating that all are primarily allogamous. Some plants have basal and lower cauline leaves with exaggeratedly and irregularly toothed-incised margins...".
Nesom (2012) indicates that the range of this species is the Cascade Mountains and coastal forests from northern Washington to northern California, east to central Idaho."
Nesom, G.L. 2012. Taxonomy of Erythranthe sect. Simiola (Phrymaceae) in the USA and Mexico.Phytoneuron 40: 1–123.