Among the more handsome and conspicuous of flowers of Crater Lake National Park, are the Monkey-flowers which belong to the genus Mimulus. The technical name is derived from the Greek word mimo, or ape, and was suggested by the masked or grinning corolla common to most of the species. They are conveniently separated by color into two groups, the yellows and the reds; and are characterized by having funnel- to bell-shaped, more or less irregular two-lipped flowers. In size of plant and flower, they vary greatly, running the full gamut within our limits, from the tiniest monkey to the giant simian. Six species are know to occur in the park area, one half in each color group.

The largest and most attractive species is Lewis's Monkey-flower (M. Lewisii Pursh), common along streams and lake shore, especially abundant about the boat landing. The plant usually forms large clumps with many strikingly beautiful flowers of rose-pink color, about an inch and a half in length. The name was given by the German botanist Pursh in honor of Meriweather Lewis for the Lewis and Clark expedition, who collected the type on the return trip in 1806.

The most common of the yellow forms is M. Guttatus DC. This also is a water-loving plant. Many of the streaks of yellow to be seen on the inner wall of the crater are due to their presence, marking the course of streamlets; and massed on mossy fallen logs within the stream, their golden-yellow lends much to the beauty of Boundary Spring.

Not so showy, and less frequently seen, is the Musky Monkey-flower (M. moschatus Dougl.), so named by David Douglas, the greatest of all our early botanical explorers of the north-west. The flowers are about the same size but of a pale yellow, and with weak stems, often prostrate. They are found rather sparingly in moist places, especially at lower levels. The common name is in allusion to the strong musky scent. The whole plant is moistly viscid.

Abundant in wet meadows and mossy stream margins, is the beautiful smaller yellow Primrose Monkey-flower (M. primuloides Benth.). Unlike the other forms, the flowers are borne on leafless stems which arise from the clustered basil leaves.

Growing only in dry situations is the dwarf Monkey-flower (M. nanus H. & A.). As suggested by the specific name, the plant is small, being from about an inch to three or four inches high with flowers usually little over half an inch in length. Widely distributed over the upper areas of the Park, attractive colonies are found in the pumice sand, especially notable in some places on Cloud Cap where deep red patches are frequent along the rim road.

Last, as well as least, we have Brewer's Monkey-flower (M. Breweri Gray). This pigmy of the lot is also a drylander, and most often found on precipitous, ledgy slopes, springing up and flowering immediately following the disappearance of the snow. Dense colonies are to be found among the ledges near and westward from Government Camp. Many of the plants are less than an inch high, and few exceed two or three inches. Glanuar-viscid throughout, the simple slender stem bears commonly one or two rose-pink flowers which average perhaps a quarter of an inch in length, with a corolla spread of not more than half that. With a nearly regular corolla, this little fellow presents a countenance of a more serious mien than that of his grinning relatives. Some of his associates are also diminutive plants. Among them are the Little Knotweed (Polygonum minimum Wats.) often only one half to an inch high with exceedingly small flowers; the Small-flowered Collinsia (Collinsia parviflora Dougl.), and the Little Willow Herb (Depilobium minimum Bindl). The name was given by Dr. Gray in honor of its discoverer, W. H. Brewer, who was the first to make any considerable plant collections in the high Sierras of California. Several other Crater Lake plants bear his name, including Brewer's Sedge (Carex Breweri Boot.) and Brewer's Mitella (Mitella Breweri Gray).