Flora of North America species comparison

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Erythranthe microphylla

Erythranthe arvensis

Bentham's monkeyflower, small-leaf monkey-flower

field monkey-flower, villous-bract monkeyflower, western monkey-flower
Habit Annuals, fibrous-rooted. Annuals, taprooted or fibrous-rooted, sometimes rooting at proximal cauline nodes if decumbent.
Stems

erect, simple, sometimes many-branched from basal cauline nodes, terete, sometimes distinctly 4-angled, (3–)5–30(–45) cm, glabrous below inflorescence, sometimes distals hirtellous, hairs commonly deflexed, or mixed hirtellous and stipitate-glandular, sometimes only short villous-glandular, hairs gland-tipped.

erect to decumbent-ascending, simple or branched from proximal to medial nodes, usually 4-angled, fistulose to very narrow, 5–70 cm, glabrous, sometimes minutely hirtellous in inflorescence, hairs deflexed, eglandular.
Leaves

basal and cauline, basal sometimes absent at flowering;

petiole: basal or proximals to medials 3–25(–35) mm, distals 0 mm (then blade subclasping to narrowly perfoliate);

blade often purplish, palmately 3–5-veined, ovate or ovate-lanceolate to elliptic-ovate, suborbicular, or depressed-ovate, (3–)10–35 × 3–25 mm, base rounded to truncate or subcordate, margins shallowly crenate to sharply crenate-serrate, teeth 5–10 per side, basal and proximal often irregularly incised near petiole and sublyrate, apex acute to obtuse-rounded, surfaces glabrous or sparsely to moderately hirtellous, eglandular.

basal and cauline or basal not persistent, often largest at mid stem or above, reduced in size distally;

petiole 3–20(–90) mm, distals 0 mm;

blade palmately 3–5-veined, ovate to orbicular, orbicular-ovate, oblong-ovate, or (middle and distal cauline) broadly orbicular to depressed-ovate or nearly reniform, (5–)10–35(–45) × 6–26(–50) mm, distal closely paired, auriculate-subclasping, base rounded to truncate, subcordate, or shallowly cordate, margins denticulate or subentire to distinctly dentate, on larger plants proximal characteristically lacerate-lobed to pinnatifid at margin base, apex rounded, surfaces glabrous except for bracts densely villous abaxially, sometimes also adaxially, hairs long, sometimes vitreous, flattened, eglandular, multicellular.
Flowers

herkogamous, 1–8(–14), usually from distal nodes, chasmogamous.

plesiogamous, 3–8(–16), from remote distal nodes, chasmogamous or cleistogamous.
Styles

sparsely hirtellous.

glabrous.
Corollas

yellow to golden yellow or orangish yellow, usually red-spotted, abaxial limb sometimes with a large red splotch, bilaterally symmetric, bilabiate;

tube-throat broadly funnelform, (6–)8–16(–20) mm, exserted (1–)2–6(–8) mm beyond calyx margin;

limb expanded 8–25 mm, palate villous.

yellow, usually red-spotted, weakly bilaterally or nearly radially symmetric, weakly bilabiate or nearly regular;

tube-throat cylindric-funnelform, (7–)8–12 mm, exserted (0–)1–2(–3) mm beyond calyx margin;

limb expanded 5–10 mm.
Fruiting pedicels

8–30(–50) mm, distals hirtellous, hairs commonly deflexed, or mixed hirtellous and stipitate-glandular, sometimes only short villous-glandular, hairs gland-tipped.

5–40(–90) mm, longer than subtending leaves, glabrous.
Fruiting calyces

nodding 30–90º, sometimes red-tinged or -dotted, ovoid-campanulate to broadly cylindric-campanulate, inflated, sagittally compressed, (7–)9–16(–20) mm, minutely hirtellous, hairs sometimes reduced to basal cells, or glabrous, throat strongly to weakly closing.

red-dotted or not, ovate-campanulate, inflated, sagittally compressed, (7–)9–14 mm, minutely hirtellous, throat closing or not, remaining open, lobes upcurving weakly, adaxial lobe not distinctly longer than abaxial, not falcate.
Capsules

included, 6–9(–11) mm.

included, stipitate, (5–)6–7 mm.
Anthers

included, glabrous.

included, glabrous.
2n

= 28, 56.

= 28.

Erythranthe microphylla

Erythranthe arvensis
Phenology Flowering Mar–Jul. Flowering Apr–Jun(–Jul).
Habitat Rock depressions, rocky ridges, cliff faces, roadcuts, wet meadows, seeps, stream banks, drying ponds, ephemeral stream channels, vernal springs over serpentine, roadsides and roadside ditches, dry banks, lava soils, loam, clay, gravel, yellow pine, oak-pine, mixed oak woodlands, oak-chaparral. Hills, ridges, clay banks, stream banks, moist woods.
Elevation 20–1700(–2600) m. (100–5600(–8500) ft.) 30–1900(–2300) m. (100–6200(–7500) ft.)
Distribution
from FNA
CA; ID; NV; OR; WA; BC
[WildflowerSearch map]
from FNA
CA; ID; MT; NV; OR; UT; WA; WY; BC; Mexico (Baja California)
[WildflowerSearch map]
Discussion

Erythranthe microphylla is characterized by its annual duration (fibrous-rooted), usually simple stems, relatively widely spaced leaves, glabrous or hirtellous vestiture, open corollas, and calyces closing at the throat. Even in the smallest corollas, the stigma is positioned above the adaxial anther pair, indicating that all are primarily allogamous. Some plants have basal and proximal cauline leaves with exaggeratedly and irregularly toothed-incised margins (especially in Lake and Napa counties, California, as in the types of Mimulus glareosus and M. guttatus var. insignis, respectively), but a similar tendency can be seen over most of the geographic range. Plants of E. microphylla vary greatly in height, leaf size, and flower size (the larger flowers approaching the size of those in E. grandis and E. decora), yet all seem to be within the expression of a single species.

An inversion sequence of chromosome 8 (the DIV1 region) is perfectly correlated with the life history features of at least four species of sect. Simiolus (D. B. Lowry and J. H. Willis 2010). One sequence occurs in Erythranthe guttata and E. grandis, which are perennial and rhizomatous, occur in habitats with year-round moisture, and flower relatively late in the season, while the opposite sequence occurs in E. nasuta and E. microphylla, which are annual and slender-taprooted or fibrous-rooted, occur in quickly drying habitats, and flower in early season. The inversion, with its tightly linked, locally adaptive alleles, contributes to isolating mechanisms between species with contrasting sequences and preserves the constellation of features that makes each a recognizable entity.

Hybridization and apparent introgression occur among Erythranthe guttata, E. microphylla, and E. nasuta, yet each remains distinct in duration, perennating morphology, and habit. Erythranthe arvensis (annual) also is a member of this gene-sharing group. A whole-genome analysis by A. D. Twyford and J. Friedman (2015) showed that populations of E. guttata and E. microphylla cluster together within each of several geographically delimited regions; they interpreted their trees as showing phylogenetic relationships and concluded that E. guttata and E. microphylla are conspecific. Other evidence (G. L. Nesom 2014c, 2014d), particularly the DIV1 inversion sequence, indicates that E. guttata and E. grandis are most closely related to each other and were derived from an ancestor of annual duration. Thus, E. microphylla and E. nasuta are morphologically and phylogenetically distinct from E. guttata, despite extensive gene flow where they are sympatric with it.

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

Erythranthe arvensis usually is easily recognized, characterized by its annual duration (but commonly rooting at proximal cauline nodes, suggestive of a rhizomatous habit), glabrous stems with nodes relatively few and remotely spaced, depressed-ovate leaves with margins often sublyrate (lacerate-lobed to subpinnatifid) at the base, distal leaves and bracts densely villous with vitreous eglandular hairs, other leaves glabrous, and corollas varying in size from relatively small but perhaps chasmogamous (the type of Mimulus arvensis) to even smaller (cleistogamous; the type of M. micranthus). The breeding system is consistently autogamous. The relatively short and even-sized calyx lobes that do not turn upward to close the orifice have been considered diagnostic of E. arvensis. This feature is evident in some plants, but others (perhaps reflecting gene flow from other species) have a longer adaxial calyx lobe and abaxial lobes that turn upward variably.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 17, p. 415. FNA vol. 17, p. 420.
Parent taxa Phrymaceae > Erythranthe Phrymaceae > Erythranthe
Sibling taxa
E. acutidens, E. alsinoides, E. ampliata, E. androsacea, E. arenaria, E. arenicola, E. arvensis, E. barbata, E. bicolor, E. brachystylis, E. breviflora, E. breweri, E. caespitosa, E. calcicola, E. calciphila, E. cardinalis, E. carsonensis, E. charlestonensis, E. chinatiensis, E. cinnabarina, E. corallina, E. cordata, E. decora, E. dentata, E. diffusa, E. discolor, E. eastwoodiae, E. erubescens, E. exigua, E. filicaulis, E. filicifolia, E. floribunda, E. gemmipara, E. geniculata, E. geyeri, E. glaucescens, E. gracilipes, E. grandis, E. grayi, E. guttata, E. hallii, E. hardhamiae, E. hymenophylla, E. inamoena, E. inconspicua, E. inflatula, E. jungermannioides, E. laciniata, E. latidens, E. lewisii, E. linearifolia, E. marmorata, E. michiganensis, E. minor, E. montioides, E. moschata, E. nasuta, E. norrisii, E. nudata, E. palmeri, E. pardalis, E. parishii, E. parvula, E. patula, E. percaulis, E. primuloides, E. ptilota, E. pulsiferae, E. purpurea, E. regni, E. rhodopetra, E. rubella, E. scouleri, E. shevockii, E. sierrae, E. suksdorfii, E. taylorii, E. thermalis, E. tilingii, E. trinitiensis, E. unimaculata, E. utahensis, E. verbenacea, E. washingtonensis, E. willisii
E. acutidens, E. alsinoides, E. ampliata, E. androsacea, E. arenaria, E. arenicola, E. barbata, E. bicolor, E. brachystylis, E. breviflora, E. breweri, E. caespitosa, E. calcicola, E. calciphila, E. cardinalis, E. carsonensis, E. charlestonensis, E. chinatiensis, E. cinnabarina, E. corallina, E. cordata, E. decora, E. dentata, E. diffusa, E. discolor, E. eastwoodiae, E. erubescens, E. exigua, E. filicaulis, E. filicifolia, E. floribunda, E. gemmipara, E. geniculata, E. geyeri, E. glaucescens, E. gracilipes, E. grandis, E. grayi, E. guttata, E. hallii, E. hardhamiae, E. hymenophylla, E. inamoena, E. inconspicua, E. inflatula, E. jungermannioides, E. laciniata, E. latidens, E. lewisii, E. linearifolia, E. marmorata, E. michiganensis, E. microphylla, E. minor, E. montioides, E. moschata, E. nasuta, E. norrisii, E. nudata, E. palmeri, E. pardalis, E. parishii, E. parvula, E. patula, E. percaulis, E. primuloides, E. ptilota, E. pulsiferae, E. purpurea, E. regni, E. rhodopetra, E. rubella, E. scouleri, E. shevockii, E. sierrae, E. suksdorfii, E. taylorii, E. thermalis, E. tilingii, E. trinitiensis, E. unimaculata, E. utahensis, E. verbenacea, E. washingtonensis, E. willisii
Synonyms Mimulus microphyllus, M. glareosus, M. guttatus var. depauperatus, M. guttatus var. insignis, M. guttatus var. microphyllus, M. guttatus var. platycalyx, M. langsdorffii var. insignis, M. langsdorffii var. microphyllus, M. luteus var. depauperatus, M. nasutus var. insignis, M. platycalyx Mimulus arvensis, M. guttatus subsp. arvensis, M. guttatus var. arvensis, M. guttatus subsp. micranthus, M. langsdorffii var. arvensis, M. longulus, M. micranthus
Name authority (Bentham) G. L. Nesom: Phytoneuron 2012-39: 44. (2012) (Greene) G. L. Nesom: Phytoneuron 2012-39: 43. (2012)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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