Bush Monkeyflower

In spring, bright drifts of bush monkeyflower (Mimulus aurantiacus) bloom in the coastal sage scrub and chaparral. Flowers range from salmon, through orange and bronze, to deep red. Can you see a monkey’s face in the flower?

Bush monkeyflower has an unusual adaptation to aid pollination. Before fertilization, the stigma is open, appearing like a white, lobed platter. When brushed by an insect the lobes fold together. If pollen has been deposited, the stigma remains closed, securing the pollen, and initiating fertilization and seed development. Otherwise, it opens again.

Description ^2,4,59

Bush monkeyflower is a woody perennial or subshrub, usually less than five feet (150 cm) high. Leaves are narrowly elliptical or lanceolate, usually less than four inches (10 cm) long. Margins are often tightly rolled under, giving the leaf a linear shape. Leaves are opposite on the stem, and both surfaces of the leaves are the same shade of green, or nearly so. Leaves are glandular, and the exuded resin gives them a sticky feel; this is particularly true of the younger leaves on a warm day. Leaves are semi-drought-deciduous.

Flowers are bilaterally symmetrical with five petals united into a two-lipped tube with two petals up and three below. The tube is pleated. There are four anthers and a pistil with a conspicuous two-lobed stigma. There are usually two flowers per node. The peak bloom period is March to August.¹

The fruit is a linear capsule with many tiny seeds. Seeds are released through a slit along the top of the capsule.

Classification

Bush monkey flower is a dicot angiosperm. For many years, monkeyflowers were considered members of the fiqwort family (Scrophulariaceae) but they were moved to the lopseed family (Phrymaceae) in 1998 on the basis of DNA sequencing.(84,88) Many available references still present the earlier classification system.  Bush monkeyflower is the only species of Phrymaceae reported in the Reserve.

The taxonomy of bush monkeyflower is a tangled subject that most sane people will want to avoid. There are many regional variants with intergrading hybrids;²⁷ between one and thirteen species have been recognized in California.²⁴ This uncertainty as to species’ boundaries is confounded by the fact that, as of 2018, bush monkeyflower is listed both in the genus Mimulus and in the genus Diplacus. As the most local authority, we follow the policy of the Jepson Manual and call our species Mimulus aurantiacus;²

The different species/varieties are generally distinguished by flower color and by the degree and location of pubescence (presence of small hairs). Most of the plants in the Reserve have flowers that range from salmon and orange to bronze to red, and have little or no pubescence. This places them in the puniceus group, recognized as a variety by the Jepson Manual: Mimulus aurantiacus var.puniceus.

Note: as of Nov. 2018, Jepson has adopted Diplacus puniceus as the official name.

Ecology

Monkeyflowers are pollinated by a variety of birds and insects including hummingbirds, bees, sphinx moths⁵⁹ and flies.³⁴ The two-lobed stigma is touch sensitive;²⁴ when brushed (by a pollinator or a curious person) the lobes fold together. If pollen has been deposited, fertilization is initiated and the stigma will remain closed permanently; otherwise it reopens after a short time.²⁷ This serves several purposes: 1) newly deposited pollen (presumably from another plant) is retained to initiate fertilization; 2) because the stigma is folded when the pollinator departs, self-pollination is reduced;³⁴ 3) the folded stigma signals future pollinators that the flower has already been visited.²⁷

The sticky resin produces by the leaf glands serves as a deterrent to the larvae of the variable checkerspot butterfly for which this species is a host plant.⁷⁷ The resin may also inhibit water loss.⁷⁸

Human Uses

The Kumeyaay used monkeyflower primarily for medicinal purposes, from poltices for burns and wounds to treatments for colds, coughs, flus, stomach disorders and heart ailments.¹⁸ Some native Americans used the young stems and leaves of monkeyflower for salad greens.³⁴

Bush monkeyflowers, with their many blossoms in arrays of bright colors, are an important garden plant with many named selections available from nurseries.^24,79

Interesting Facts

The origin of the common name remains a mystery.²⁴ No one admits to seeing a monkey face in the flower. The generic name,Mimulus, comes either from the Greek word for ape (which might be the basis for the common name as well) or from the Latin word for mime, and it has been suggested that either the flowers or markings on the seed resemble grinning faces.^23,34  The specific name aurantiacus is a Latin word for an orangish color, while the varietal name puniceus refers to a red color.²¹