Flora of North America species comparison

Plants of Erythranthe tilingii are characterized by their relatively low stature and stems arising from a system of thin rhizomes and producing mostly one to three large flowers each; they usually occur at relatively high elevations. Erythranthe tilingii sometimes has been considered to include one or several infraspecific entities; from within this taxonomic amalgam, four distinct species are recognized here: E. caespitosa, E. corallina, E. minor, and E. tilingii. Erythranthe corallina and E. minor probably are more closely related to E. guttata. The populations identified here as E. tilingii from northeastern Oregon northeast to Alberta and southeast to Utah may prove to be a separate (undescribed) species.

Erythranthe tilingii in the strict sense is relatively widespread over the western United States and is sympatric with E. caespitosa and E. corallina. Leaves in E. tilingii are variable in size, and particularly in Idaho, they may approach the small size of those of E. caespitosa, but the leaf margins of E. tilingii are distinctly toothed, and the stems are taller and more erect. Across the range of the species, plants sometimes produce very large leaves, but these often occur on plants with characteristically smaller leaves. This wide variability in size apparently does not occur in E. caespitosa.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Erythranthe guttata is markedly variable in stature, leaf shape, vestiture, flower size, and the separation distance between anthers and stigma; it ranges from subalpine and near-alpine habitats into desert situations where water is available.

In all of Colorado, the Four Corners area, and north-central New Mexico, the vestiture of stems and calyces is consistently densely hirsute-hirtellous, without glandular hairs. Plants with similar vestiture also occur in British Columbia, Oregon, and Washington, and in scattered localities elsewhere. In northwestern Arizona, California Nevada, and southern Oregon, vestiture is consistently villous-glandular, without eglandular hairs. Elsewhere in the geographic range the vestiture is a mix of hirsute-hirtellous (eglandular) and villous-glandular hairs. Other morphological variants and patterns, as well as variation in ploidy level, within Erythranthe guttata were discussed by G. L. Nesom (2012i).

Plants of Erythranthe guttata with extremely large corollas have been frequently collected on the Aleutian Islands, Kodiak Island, and in other Alaskan localities (for example, Admiralty Island Amakuk, Juneau, and Yakutat Bay). Corolla tube-throats are 19–26 mm, and the limbs are expanded to 18–25 mm. The type collection of E. guttata is one of these plants, and the name E. guttata may prove to apply most appropriately only to Alaskan populations. Diploids and tetraploids appear to be sympatric in Alaska.

Mimulus guttatus subsp. haidensis was described as an endemic subalpine race that occurs in and along the flanks of the Queen Charlotte Mountains on Graham Island and Moresby Island. The subspecies was distinguished on the basis of its hirtellous vestiture, but plants of similar hirtellous vestiture occur over the whole range of the species. A tetraploid chromosome number (2n = 56) was reported for subsp. haidensis from a total of five localities on Graham Island and Moresby Island (J. A. Calder and R. L. Taylor 1968, vol. 2), and diploids (2n = 28) were documented from one locality on each of the two islands. At least one of the diploids has densely hirtellous stems, pedicels, and calyces, matching the morphology of subsp. haidensis.

Erythranthe guttata is naturalized in Europe and has been introduced to the northeastern United States (Connecticut, Michigan, New York, and Pennsylvania) and eastern Canada (New Brunswick).

(Discussion copyrighted by Flora of North America; reprinted with permission.)