Eastwood Monkeyflower - Mimulus eastwoodiae, by James Ratzloff

Aquilegia Vol. 1 No. 6 November - December 1977

A rare plant will occasionally escape notice by botanists due to its secluded habitat. This has happened in Colorado with Mimulus eastwoodiae, Eastwood Monkey Flower. Although historically known to be endemic to southeastern Utah and northeastern Arizona, the first Colorado locality of M. eastwoodiae was not discovered until 1975. M. eastwoodiae was first seen and photographed in Escalante Canyon by Paul Maslin and Panayoti Callas, both from Boulder, on August 26, 1975. They did not collect specimens. Since then it has been found and collected by a number of other botanists in a variety of locations. Another locality was discovered this last summer [in 1976]. Both are in secluded canyons in the southwestern quarter of the state. The habitat of M. eastwoodiae is unique: shallow caves at the base of steep canyon walls. The caves consist of a rear wall that arches gradually upward and outward into a massive overhang. They are formed by the seepage of water out of the sandstone canyon wall; the water erodes away the sandstone, continually deepening the cave.

a photo of several Eastwood's Monkeyflower in bloom

Eastwood’s Monkey-flower (Erythanthe eastwoodiae)

M. eastwoodiae blooms in late summer, during August. By that time the Helleborine Orchid, Star Solomonplume, and Small-flowered Columbine are past bloom.

The hummingbirds that pollinate M. eastwoodiae congregate around the caves, which are shady and cool in contrast to the hot, dry Pinyon-Juniper and canyon country surrounding them. Well-worn trails to a few of the most spectacular M. eastwoodiae associations are evidence that the local nat1ves enjoyed these beautiful “oases” long before botanists discovered them. Because of its beauty and uniqueness, the M. eastwoodiae habitat is truly one of the botanical highlights of Colorado.
a photo of Eastwood's monkey-flower
Closeup: Eastwood’s Monkey-flower (Erythanthe eastwoodiae)
The water seep supports a lush association of plants, unusual in the dry, desert country. M. eastwoodiae is the uppermost stratum of these plants, growing directly out of the rock wall at the rear of the cave. It clings to the rock face by the roots of horizontal stolons. The chief plants that grow below M. eastwoodiae in the loose, moist soil are Star Solomon plume (Smilacina stellata), Helleborine Orchid (Epitactis gigantea), and Small-flowered Columbine (Aquilegia micrantha). M. eastwoodiae’s large (l½” to 2½” long) flower is bright red. It resembles a Penstemon flower in that it is tubular and two-lipped; but unlike Penstemon, it has four stamens rather than five. M. eastwoodiae’s style is longer than its stamens, and the stigma at the tip of the style is two-lobed. The plant’s leaves are ovate to obovate, toothed, and opposite on the stem.

Editor’s note: At the time that this article was written Mimulus eastwoodiae  was in the Figwort Family (Scrophulariaceae).  It has since been moved into the Lopseed family (Phyrmaceae) and its genus changed from Mimulus to Erythranthe.  It is classified as a critically imperiled (S1) species in Colorado.