FNA: Erythranthe rubella vs. Erythranthe willisii

	Erythranthe rubella	Erythranthe willisii
	little redstem monkeyflower, red stem himulus, redstem monkeyflower, redstem or little redstem monkeyflower	Willis' monkeyflower
Habit	Annuals, taprooted.	Perennials, rhizomatous, rarely rooting at proximal nodes, usually forming large colonies, rhizomes white, usually highly branching.
Stems	erect, simple, sometimes branched from basal nodes, 3–32 cm, minutely puberulent.	usually sprawling-decumbent, branched, sometimes simple, 7–45 cm, nodes (2–)4–15+, densely glandular-villous, hairs 1–2 mm, glandular, internodes evident.
Leaves	cauline, basal not persistent; petiole 0 mm; blade palmately 3-veined (in broader ones), linear to elliptic, 5–22(–30) × 1–5 mm, base narrowed, margins entire, sometimes toothed, apex acute to obtuse, surfaces minutely puberulent.	usually cauline, basal not persistent, distinctly separated; petiole 0 mm, sometimes 1–2 mm at proximal nodes; blade bicolored, purplish abaxially, pinnately veined, ovate to elliptic-ovate, midcauline 10–35 × 6–18 mm, base rounded to subcordate, margins coarsely serrate-dentate to denticulate or subentire, apex short-attenuate to acute, obtuse, or rounded, surfaces densely glandular-villous, hairs 1–2 mm, gland-tipped.
Flowers	herkogamous, sometimes plesiogamous, 1–106, from distal or medial to distal nodes.	herkogamous, (4–)8–30+, from medial to distal nodes, sometimes from all nodes.
Styles	glabrous.	glabrous.
Corollas	yellow and abaxial limb and throat red dotted or pink to purple and throat yellow, bilaterally symmetric, weakly bilabiate; tube-throat cylindric, 4–10 mm, exserted beyond calyx margin; limb expanded 3–5 mm, lobes entire or weakly notched, abaxial limb glabrous.	yellow, throat, tube, and proximal portion of abaxial 3 lobes with fine, red to brownish lines, weakly bilaterally or nearly radially symmetric, weakly bilabiate or nearly regular; tube-throat narrowly funnelform, 12–15 mm, exserted beyond calyx margin; limb 9–12 mm wide (pressed), lobes oblong-obovate, apex rounded to notched.
Fruiting pedicels	2–18 mm.	4–20(–25) mm, densely glandular-villous, hairs 1–2 mm, gland-tipped.
Fruiting calyces	becoming red-angled or red, campanulate to nearly cylindric, 4–9 mm, margins distinctly toothed or lobed, glabrous or minutely puberulent, ribs thickened, lobes pronounced, erect, margins ciliate.	ridge- to wing-angled, campanulate to cylindric-campanulate, weakly inflated, 7–10 mm, densely glandular-villous, lobes erect to slightly spreading, unequal, triangular to linear-lanceolate, 2–4 mm, apex acuminate-apiculate.
Capsules	included, 3–8 mm.	included, 4–5 mm.
Anthers	included, glabrous.	included, glabrous or finely hirtellous to scabrous.

	Erythranthe rubella	Erythranthe willisii
Phenology	Flowering Apr–Jun.	Flowering May–Sep.
Habitat	Open slopes and washes.	Seepage, drainage margins, moist soils, talus, cracks and crevices, soils deprived from serpentine.
Elevation	300–3000 m. [1000–9800 ft.]	(500–)700–900 m. [(1600–)2300–3000 ft.]
Distribution	AZ; CA; CO; NM; NV; TX; UT; WY; Mexico (Baja California, Sonora) [WildflowerSearch map]	CA
Discussion		Erythranthe willisii is narrowly endemic over serpentine along the North Fork Feather River (including the North Branch) in Plumas County. In the original description, its range was said to include serpentine localities in closely adjacent areas of east-central Butte, Plumas, and northwestern Yuba counties, but subsequent field work has shown that these peripheral populations are E. moschata, and that E. willisii occurs only in the bottom of the Serpentine Canyon area. The most consistent and recognizable features of E. willisii are the long, sprawling stems often spread over a large area, sometimes reaching at least 45 cm and often with many crowded nodes, sessile or subsessile leaves with rounded to subcordate bases, and short pedicels, characteristically no longer than the subtending leaves (except sometimes the distal ones where subtending leaves are distinctly reduced in size). It is possible that stem growth in E. willisii is indeterminate versus determinate in E. moschata. Sessile to subsessile leaves occur in E. moschata, especially in the California Sierra Nevada, but petiole length and leaf base shape are variable within populations; lack of petioles and a rounded/subcordate base are fixed characters in E. willisii (as they are also in E. ptilota). Although large colonies of E. moschata are sometimes encountered, the individual plants tend to be erect (in California) and with few distal flowers. In the field, the dense vestiture of E. willisii is a prominent feature, but this is harder to distinguish in pressed specimens, and there is a strong tendency for purple abaxial leaf coloration in E. willisii. Phenology and flower morphology of E. willisii and E. moschata appear to be similar, but E. moschata in north-central California does not occur at as low elevations as E. willisii. (Discussion copyrighted by Flora of North America; reprinted with permission.)
Source	FNA vol. 17, p. 384. Treatment authors: Guy L. Nesom, Naomi S. Fraga.	FNA vol. 17, p. 401. Treatment authors: Guy L. Nesom, Naomi S. Fraga.
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. 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. 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. veronicifolia	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. 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. veronicifolia
Synonyms	Mimulus rubellus, M. gratioloides
Name authority	(A. Gray) N. S. Fraga: Phytoneuron 2012-39: 35. (2012)	G. L. Nesom: Phytoneuron 2017-17: 7, figs. 14–22. (2017)
Web links	Local floras: CA Local Web sites: CalFlora, CalPhotos WildflowerSearch iNaturalist (observations) LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	WildflowerSearch iNaturalist (observations) LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Erythranthe willisii

little redstem monkeyflower, red stem himulus, redstem monkeyflower, redstem or little redstem monkeyflower

Willis' monkeyflower

Habit

Annuals, taprooted.

Perennials, rhizomatous, rarely rooting at proximal nodes, usually forming large colonies, rhizomes white, usually highly branching.

Stems

erect, simple, sometimes branched from basal nodes, 3–32 cm, minutely puberulent.

usually sprawling-decumbent, branched, sometimes simple, 7–45 cm, nodes (2–)4–15+, densely glandular-villous, hairs 1–2 mm, glandular, internodes evident.

Leaves

cauline, basal not persistent;

petiole 0 mm;

blade palmately 3-veined (in broader ones), linear to elliptic, 5–22(–30) × 1–5 mm, base narrowed, margins entire, sometimes toothed, apex acute to obtuse, surfaces minutely puberulent.

usually cauline, basal not persistent, distinctly separated;

petiole 0 mm, sometimes 1–2 mm at proximal nodes;

blade bicolored, purplish abaxially, pinnately veined, ovate to elliptic-ovate, midcauline 10–35 × 6–18 mm, base rounded to subcordate, margins coarsely serrate-dentate to denticulate or subentire, apex short-attenuate to acute, obtuse, or rounded, surfaces densely glandular-villous, hairs 1–2 mm, gland-tipped.

Flowers

herkogamous, sometimes plesiogamous, 1–106, from distal or medial to distal nodes.

herkogamous, (4–)8–30+, from medial to distal nodes, sometimes from all nodes.

Styles

glabrous.

Corollas

yellow and abaxial limb and throat red dotted or pink to purple and throat yellow, bilaterally symmetric, weakly bilabiate;

tube-throat cylindric, 4–10 mm, exserted beyond calyx margin;

limb expanded 3–5 mm, lobes entire or weakly notched, abaxial limb glabrous.

yellow, throat, tube, and proximal portion of abaxial 3 lobes with fine, red to brownish lines, weakly bilaterally or nearly radially symmetric, weakly bilabiate or nearly regular;

tube-throat narrowly funnelform, 12–15 mm, exserted beyond calyx margin;

limb 9–12 mm wide (pressed), lobes oblong-obovate, apex rounded to notched.

Fruiting pedicels

2–18 mm.

4–20(–25) mm, densely glandular-villous, hairs 1–2 mm, gland-tipped.

Fruiting calyces

becoming red-angled or red, campanulate to nearly cylindric, 4–9 mm, margins distinctly toothed or lobed, glabrous or minutely puberulent, ribs thickened, lobes pronounced, erect, margins ciliate.

ridge- to wing-angled, campanulate to cylindric-campanulate, weakly inflated, 7–10 mm, densely glandular-villous, lobes erect to slightly spreading, unequal, triangular to linear-lanceolate, 2–4 mm, apex acuminate-apiculate.

Capsules

included, 3–8 mm.

included, 4–5 mm.

Anthers

included, glabrous.

included, glabrous or finely hirtellous to scabrous.

Erythranthe rubella

Erythranthe willisii

Phenology

Flowering Apr–Jun.

Flowering May–Sep.

Habitat

Open slopes and washes.

Seepage, drainage margins, moist soils, talus, cracks and crevices, soils deprived from serpentine.

Elevation

300–3000 m. [1000–9800 ft.]

(500–)700–900 m. [(1600–)2300–3000 ft.]

Distribution

AZ; CA; CO; NM; NV; TX; UT; WY; Mexico (Baja California, Sonora)

[WildflowerSearch map]

Discussion

Erythranthe willisii is narrowly endemic over serpentine along the North Fork Feather River (including the North Branch) in Plumas County. In the original description, its range was said to include serpentine localities in closely adjacent areas of east-central Butte, Plumas, and northwestern Yuba counties, but subsequent field work has shown that these peripheral populations are E. moschata, and that E. willisii occurs only in the bottom of the Serpentine Canyon area. The most consistent and recognizable features of E. willisii are the long, sprawling stems often spread over a large area, sometimes reaching at least 45 cm and often with many crowded nodes, sessile or subsessile leaves with rounded to subcordate bases, and short pedicels, characteristically no longer than the subtending leaves (except sometimes the distal ones where subtending leaves are distinctly reduced in size). It is possible that stem growth in E. willisii is indeterminate versus determinate in E. moschata. Sessile to subsessile leaves occur in E. moschata, especially in the California Sierra Nevada, but petiole length and leaf base shape are variable within populations; lack of petioles and a rounded/subcordate base are fixed characters in E. willisii (as they are also in E. ptilota). Although large colonies of E. moschata are sometimes encountered, the individual plants tend to be erect (in California) and with few distal flowers. In the field, the dense vestiture of E. willisii is a prominent feature, but this is harder to distinguish in pressed specimens, and there is a strong tendency for purple abaxial leaf coloration in E. willisii. Phenology and flower morphology of E. willisii and E. moschata appear to be similar, but E. moschata in north-central California does not occur at as low elevations as E. willisii.

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

Source

FNA vol. 17, p. 384. Treatment authors: Guy L. Nesom, Naomi S. Fraga.

FNA vol. 17, p. 401. Treatment authors: Guy L. Nesom, Naomi S. Fraga.

Parent taxa

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. 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. 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. veronicifolia

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. 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. veronicifolia

Synonyms

Mimulus rubellus, M. gratioloides

Name authority

(A. Gray) N. S. Fraga: Phytoneuron 2012-39: 35. (2012)

G. L. Nesom: Phytoneuron 2017-17: 7, figs. 14–22. (2017)

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).

The species comparison tool is brought to you by:

Flora of North America species comparison

Erythranthe rubella

Erythranthe willisii

Erythranthe rubella

Erythranthe willisii