Wildflowers of the United States

Japanese Mazus - Mazus pumilus

Genus Common Name: Mazus

Native Status: Introduced

Dicot Annual Herb

Mazus pumilus - Japanese Mazus. The Mazus genus probably has been feeling like an unwanted 19th century orphan lately, being bounced around from family to family. Originally placed in Scrophulariaceae, a 2002 study by Beardsley and Olmstead placed Mazus, Lancea, and Mimulus in the long-neglected Phrymaceae family. Hardly having time to get comfortable there, publications in 2009 (D. C. Albach et al.) and in 2011 (J. L. Reveal) resulted in the circumscription of a new family - Mazaceae, when Mazus and Lancea were shorn of their close relationship with Mimulus (and others) and place as the only two genera in that new family. Since, as of January 2014 the Integrated Taxonomic Information System (ITIS) has yet to accept this new classification and still has Mazus in Phrymaceae (USDA Plants Database continues to list it in Scrophulariaceae) and I usually follow ITIS in these family squabbles, I am placing Mazus pumilus in Phrymaceae until it's had time to settle into Mazaceae.

Mazus pumilus (syn. Mazus japonicus,) an annual, is one of about 30 species in the genus, but one of only two found in North America. It and Mazus miquelii (Creeping Mazus,) a perennial, are both introduced species, and both are natives of eastern Asia. Mazus miquelii has a slightly larger flower, and is prone, whereas Mazus pumilus is an upright plant. M. miquelii also has a much smaller distribution in the United States, being found in only 8 states, while M. pumilus is found throughout much of the eastern United States as well as in the Pacific coast states, a total of 29 states. They are both found in lawns and other man-disturbed habitats.

Found in:
AL, AR, CA, CT, DC, DE, FL, GA, IL, IN, KY, LA, MA, MD, MO, MS, NC, NJ, NY, OH, OK, OR, PA, SC, TN, TX, VA, WA, WI, WV

Distribution of Mazus pumilus in the United States and Canada:

Map courtesy of The Biota of North America Program.
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Site: Camp Vesper Point, Hamilton County, TN Date: 2013-September-13	Photographer: Gerald C. Williamson Nikon D7000 Tamron SP 90MM f/2.8 AF Macro
The flower of Japanese Mazus is about .3 to .4 inches long, with a two-lipped, blue-violet corolla; the upper lip narrows to a toothed tip; the lower lip is 3-lobed (Flora of North America reports that these are 5 petals which are fused at their lower end - connate proximally.) The interior has a white throat with yellowish-orange oval lobes - to me they look like sunnyside-up eggs, but the genus name Mazus comes from the Greek for breast, reflecting another perspective on what they look like.

Site: Camp Vesper Point, Hamilton County, TN Date: 2013-September-13	Photographer: Gerald C Williamson Nikon D7000 Tamron SP 90MM f/2.8 AF Macro
Mazus pumilus, Japanese Mazus, is an erect plant to 6 or 8 inches tall. The leaves are mostly basal, where they are on petioles with an ovate or obovate blade. The stem leaves have reduced petioles or are sessile; the lower ones are opposite, and reduced and alternate higher on the stem. The stem is somewhat hairy; the cauline leaf petioles may also be hairy.
Click on the photo for a larger image

References used for identification and information:

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Mazus pumilus initially published on USWildflowers.com 2014-01-24; Updated 2017-03-02

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All content except USDA Plants Database map Copyright Gerald C. Williamson 2024
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Code Update 20230302