Mimulus hymenophyllus is a species of flowering plant in the lopseed family

Phrymaceae

Phrymaceae , also known as the Lopseed family, is a small plant family in the order Lamiales. It now consists of about 190 species, distributed worldwide but with the majority in western North America and Australia .Previously, this family was monotypic with the genus Phryma, and limited in...

 known by the common names thinsepal monkeyflower and membrane-leaf monkeyflower. It is native to Hells Canyon

Hells Canyon

Hells Canyon is a wide canyon located along the border of eastern Oregon and western Idaho in the United States. It is North America's deepest river gorge at and part of the Hells Canyon National Recreation Area....

 on the border between Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

 and Idaho

Idaho

Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....

 in the United States. It has also been reported from Montana

Montana

Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...

.

This plant is a perennial herb producing masses of thin, fragile, winged stems up to 25 centimeters long. They are coated in glandular hairs with a slimy exudate. The leaves are oppositely arranged in pairs. They are lance-shaped to oval with pointed tips and are very thin, nearly membrane-like. Flowers are borne in pairs in the leaf axils. Each has a tube-shaped calyx of green sepal

Sepal

A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...

s. The corolla is funnel-shaped and variable in size, up to 2.8 centimeters in length. It is yellow with some red or purple dots inside, and it has a beard of yellow hairs on the lower lip. Flowering occurs in April through September.

This plant grows on wet spots in cracks in basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

 and limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 cliffs alongside ferns and bryophyte

Bryophyte

Bryophyte is a traditional name used to refer to all embryophytes that do not have true vascular tissue and are therefore called 'non-vascular plants'. Some bryophytes do have specialized tissues for the transport of water; however since these do not contain lignin, they are not considered to be...

s. They are usually above flowing water in streams and rivers. Other plants in the habitat include oceanspray

Holodiscus discolor

Holodiscus discolor, commonly known as ocean spray, creambush or ironwood, is a shrub of western North America. It is common in the Pacific Northwest where it is found in both openings and the forest understory at low to moderate elevations.-Description:Holodiscus discolor is a fast-growing...

 (Holodiscus discolor), snowberry

Symphoricarpos albus

Symphoricarpos albus is a species of flowering plant in the honeysuckle family known by the common name common snowberry. It is native to North America, where it occurs across much of Canada and the northern United States. It grows in shady and moist mountain and forest habitat, in woodlands and on...

 (Symphoricarpos albus), creeping mahonia (Mahonia repens), desert gooseberry

Ribes velutinum

Ribes velutinum is a species of currant known by the common name desert gooseberry. It is native to the western United States , where it grows in many types of habitat, including sagebrush, woodlands, and pine forests. R. v. var...

 (Ribes velutinum), golden currant

Ribes aureum

Ribes aureum Pursh is a species of small to medium-sized deciduous shrubs 2 to 3 meters tall in the genus Ribes...

 (Ribes aureum), Wilcox penstemon (Penstemon wilcoxii), whorled penstemon (Penstemon triphyllus), floerkea (Floerkea proserpinacoides), Leiberg stonecrop (Sedum leibergii), cutleaf thelypody

Thelypodium laciniatum

Thelypodium laciniatum is a species of flowering plant in the mustard family known by the common name cutleaf thelypody. It is native to western North America, particularly the Great Basin and surrounding plateau and foothill habitat, where it grows in sagebrush, scrub and rocky hillsides. It is a...

 (Thelypodium laciniatum), brittle bladderfern

Cystopteris fragilis

Cystopteris fragilis is a species of fern known by the common names brittle bladderfern and common fragile fern. It can be found worldwide, generally in shady, moist areas. The leaves are up to 30 or 40 centimeters long and are borne on fleshy petioles. Each leaf is divided into many pairs of...

 (Cystopteris fragilis), and common monkeyflower

Mimulus guttatus

Mimulus guttatus, the Common monkey-flower, is a yellow bee-pollinated annual or perennial herbaceous wildflower that grows along the banks of streams and seeps in western North America.-Description:...

 (Mimulus guttatus).

This Mimulus is considered to be a member of the Snake River Clade (with Mimulus ampliatus and M. patulus) of the Mimulus moschatus

Mimulus moschatus

Mimulus moschatus is a species of monkeyflower known by the common name muskflower.-Distribution:It is native to western North America from British Columbia to California to the Rocky Mountains, where it grows in moist, partially shaded habitat in mountains, woodlands, chaparral, and other areas.It...

alliance.