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Mimulus guttatus complex


The Mimulus guttatus complex comprises a large number of species, and is taxonomically controversial. On this page are mounted pictures of all the species that I and my group have worked on. Click on the thumbnails to obtain clearer pictures. I will include any other pictures that are sent to me by others interested in this group.

Mimulus guttatus sensu stricto

Found naturally in the west of North America in damp places from sea level to over 3000m in the Rockies and other mountains. It is very variable. It is now naturalised in Britain and Europe, Eastern North America and New Zealand. It is the presumed progenitor of most of the rest of the species listed here which have much more limited distribution.

Picture of Mimulus guttatus flower
Picture of Mimulus guttatus flower © Mark Macnair

Mimulus nasutus

This species was described by Greene (1885, Bull. Calif. Acad. Sci. 1:112-113) who commented "It is an exceedingly well marked, apparently until now undescribed species. Nevertheless a plant so far from rare will doubtless be found in many herbaria, and probably under the heretofore so-called M. luteus [=M. guttatus]". This is certainly true, and different authors have had different concepts of this species, which may explain some of the confusion surrounding it. Vegetatively it is difficult to distinguish from Mimulus guttatus, but its flowers are smaller, with a corolla tube longer than the width of the flower. It is annual, and produces cleistogamous flowers. The early, large flowers are often chasmogamous, though functionally cleistogamous, but later flowers, and flowers on small sidebranches, are cleistogamous. The cleistogamous flowers, though not mentioned by Greene, are present on the type specimens and can be taken as the character most clearly distinguishing this species from M. guttatus. It tends to grow in cracks in rocks and other marginal habitats, and is more shade tolerant than M. guttatus. It is very widespread in California and Oregon, and has recently become established at the University of Exeter in Britain. Here it grows in the cracks in paving stones and between bricks, similarly to the habitats in which it grows in California. It is spreading around the building at about 5m a year! Note that M. guttatus has never established a feral population around the University in the same way, despite far more of this species being grown than M. nasutus!

Habitat shot of Mimulus nasutus
growing in a mixed clump with M. guttatus in Shirley Creek, Calaveras Co, California. The red lines indicate M. nasutus flowers
© Mark Macnair


Detail of above picture. Red line - M. nasutus; blue line- M. guttatus
© Mark Macnair

Mimulus laciniatus

Small, branched annual species restricted to the high Sierra Nevada from Tuolumne County to Tulare County. Primarily distinguished by its highly dissected leaves, it can also form cleistogamous flowers, and indeed its flowers and capsules resemble those of M. nasutus in many ways.


Photo taken by Brother Alfred Brousseau, © 1995 St Mary's College California.

Mimulus nudatus

This is a serpentine endemic restricted to ultramaphic substrates in Lake and Napa counties, California. It has narrow, small leaves, and is a small, much branched plant that is obligately annual. It is outcrossing, and may be pollinated by both bumble bees and solitary bees.

Habitat shot of Mimulus nudatus
growing in serpentine soil
© Mark Macnair


Detail of above picture
© Mark Macnair

Mimulus pardalis

This species was recognised by Pennell (1950) but has been reduced to synonymy by most other authors. It is a serpentine endemic restricted to ultramaphic substrates in the mid Sierra Nevada, California. It has narrower leaves than M. guttatus. It is a highly branched, small annual species, believed to be self-fertilising. It does not form cleistogamous flowers.

Mimulus pardalis (right)
growing in serpentine soil
together with M. guttatus(left)
along Highway 49, California
© Mark Macnair


Detail of above picture
© Mark Macnair

Mimulus cupriphilus

This species is restricted to two small copper mines in Calaveras County, California. It is highly branched and obligately annual. It is self-fertilising, but not cleistogamous. It has reduced corolla spots, and its corolla lobes are pointed.


Mimulus cupriphilus and M. guttatus
growing in a mixed population on the McNulty
mine, Calaveras Co, California.
© Mark Macnair

Mimulus marmoratus

This species was described by Greene, but has not been subsequently recognised. It appears to be restricted to a small area of Calaveras County, California. It is obligately annual and appears to be self-fertilising. We found it growing on the basalt and conglomerate at the top of Table Mountain, Calaveras Co, in a situation M. guttatus would be unable to grow.

 

M. marmoratus at Knights Ferry, Calaveras Co,
California.

© Mark Macnair

Mimulus glaucescens

This is probably a variant of M. guttatus. It is restricted to a small area of Butte and Tehama Counties, California. It is distinguished from M. guttatus by connate bracts and greeny/blue appearance. Pennell (1950) suggests that it is annual, but it behaves as a perennial in the glasshouse, unlike the obligate annual segregants of M. guttatus

Mimulus glaucescens growing near Chico, Butte
County, California.
© Mark Macnair

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Prof Mark R. Macnair,
Email: M.R.Macnair@exeter.ac.uk

Last updated 22/01/01