Shield-bracted monkeyflower (Erythranthe glaucescens) is probably 2 species

Shield-bracted monkeyflower (Erythranthe glaucescens (Greene) G.L. Nesom) is on CNPS List 4 and is narrowly endemic to the Cascade Range foothills of Shasta, Tehama and Butte Counties, California (a CNPS report from Colusa county is not supported by a specimen).

Erythranthe glaucescens  has been variously described as either annual  (Thompson 1993, 2012) or as also perennial (Nesom 2012).   Nesom (2012, p. 61) noted this discrepancy with the notation that all but two specimens were annual :

“Plants from one locality produced filiform, small-leaved runners from basal cauline nodes: California. Butte Co.: Canon of Big Chico Creek, 26 Mar 1914, Heller s.n. (MO) and 2 Jul 1914, Heller s.n. (MO). Mcnair did not say what observations led him to interpret the duration of E. glaucescens as perennial.”

Here I note that there are indeed perennial plants which are within the current circumscription of Erythranthe glaucescens, and more specifically, that there are likely to be two natural taxa involved, which implies that one taxon is not yet described.

Plants of Erythranthe glaucescens at JEPS109856 are clearly perennial: they produce abundant stolons.  In this botanical sense, stolons are stem organs which grow at the soil surface, or just below ground, which can also form adventitious roots at the nodes, and which proliferate laterally from a parent individual.    Stolons are commonly called runners (as used also by Nesom 2012).  By contrast, rhizomes are root tissue and mimic the same lateral expansion model (and are not involved here).

My review of specimens and photographs of Erythranthe glaucescens suggest to me that two taxa are being labeled as Erythranthe glaucescens.  If I were to venture a key to the Calphotos photos, it would be:

1.  Perennial, stoloniferous.  Foliage blue-glaucuous....0177 3303 3362 0079

1’  Annual, striclty so, foliage light green... 0000 0000 0407 3343

These differences are readily seen in the isotype (CAS792) which is well preserved, and annual, vs. my specimen JEPS109856 which is clearly a stolonifrous perennial.    The images are above (face of the diversion dam [upper photo, June 28 2006) and specimen (lower photo) in vivo collected there on 1 August 2013.  In my initial primitive analysis, there seems to be an elevation and habitat separation between the two putative taxa:  glaucescens is a vernal stream or seep annual of the foothills, while the undescribed taxon is a seepage-cliff specialist of conifer forest settings at mid-elevations.

References:

Thompson, D.  1993 et 2012.  Mimulus, in the Jepson Manual (2 eds.)

Neosm, G.  Taxonomy of Erythranthe sect. Simiola (Phrymaceae) in the USA and Mexico.

Phytoneuron 2012-40: 1–123.