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Plants of the Eloise Butler Wildflower Garden

The oldest public wildflower garden in the United States

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Common Name
Spotted Bee-balm (Dotted Horsemint)

 

Scientific Name
Monarda punctata L.

 

Plant Family
Mint (LAMIACEAE)

Garden Location
Historical, not extant

 

Prime Season
Late Summer

 

 

Spotted Bee-balm is a stout native perennial, growing to 3 feet in height on 4-angled, hairy stems. As a member of the mint family it is aromatic.

Leaves are opposite, lance-like, with shallow teeth and a pointed tip. Bottoms of the leaves are hairy and paler in color from the fine hair. Leaves have short stalks with fine hair, and base of the leaf tapers to the stalk with a wing effect. Smaller leaf growths are frequently seen at the base of the leaf stalk.

The inflorescence consists of dense whorled axillary clusters of flower heads that appear above the axils of the upper bracts - but not usually at the top of the stem. These clusters are distinctly separated from each other on the stem. In the mint family this arrangement is called a 'verticillaster' where the flowers look like a whorl arrangement but are actually in separate cymes that rise from the axils of opposite bracts. Only several of the flowers in each cyme are open at one time. This arrangement is similar to that seen on the Wild Mint, Mentha arvensis, but not what you see on the other common Monardas such as Wild Bergamot or Purple Bergamot where the cyme is at the top of the stem.

The flowers are quite conspicuous, the corolla being tubular, 3/4 to 1 inch long, yellowish with purple spots. The upper corolla lip is stiff and strongly arched, the lower lip is broader. Both have hair on the outer surface. The two stamens and style are tucked tightly against the inside of the upper lip and are slightly shorter than the lip and thus do not protrude except when the anthers are with mature pollen at which point the anthers are visible. The calyx tube is green, hairy, with 5 small pointed lobes. Even more conspicuous are the whitish to lilac colored bracts that surround the cyme at its base. These growths look like leaves but are called 'bracts'.

Fruit: The mature fruit is a nutlet containing one seed. Seeds are very small and require only light and warm soil for germination.

Varieties: There are many - see notes at bottom of page.

 

Habitat: Spotted Bee-balm likes full sun in dryer areas, but not without water in hot summer periods. Seedlings are not tolerant of over watering. The root system is mostly fibrous with a few rhizomes. Multiple stems can develop from each root.

Names: The genus, Monarda, is an honorary for Spanish botanist Nicholas Monardes (1493-1588) who published a book in several editions on medicinal plants of the new world. The species, punctata, is a Latin word meaning 'dotted' and applied when some part of a plant is dotted or spotted, in this case, with color on the lip of the corolla. The author name for the plant classification - 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.

Comparisons: Due to the structure of the verticillasters, Monarda punctata, looks more like Wild Mint, Mentha arvensis but that species has green bracts separating the verticillasters. The other Monardas for comparison, which have the flower cluster at the top of the stem are M. fistulosa, Wild Bergamot, M. media, Purple Bergamot and M. didyma, Scarlet Beebalm.

See bottom of page for notes on the Garden's planting history, distribution in Minnesota and North America, lore and other references.

Spotted Beebalm inflorescence drawing

Above: Flowers appear in a cyme arrangement called a verticillaster, separate by sections of the stem and by a group of bracts. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.

Below: 1st photo - Detail of the inflorescence. 2nd photo - note the square stem with fine surface hair.

Spotted Beebalm flowers Spotted Beebalm leaf

Below: The opposite leaves have shallow teeth, short stalks, and frequently, smaller leaf growths in the axil. The underside (2nd photo) is paler in color with fine surface hair.

leaf upper side leaf under side

Below: The two stamens and style are tucked into the curve of the upper lip and not noticable until the anthers expand and slightly protrude below the lip.

flower closeup stamens

Below: Flower details - Note the stiff upper lip, less broad than the lower lip, the purple spots,and the conspicuous lilac colored bracts that surround the flower.

Spotted beebalm flower detail

Below: The root system. Note - multiple stems can rise from the root.

root

Notes:

Notes: Spotted Bee-balm is a historical Garden plant. Eloise Butler first planted it on Aug. 21, 1912 with plants obtained in Mendota, MN; and again on Sept 1st, 1912, Aug. 25, 1913, Aug. 28 and Oct. 19, 1914, 1918 and 1920, all from the same source. Martha Crone reported planting it in 1934, '35 and '39. It was still in the Garden at the time of her 1951 Garden census, but has not appeared on any later census. Spotted bee-balm has been collected in only 16 counties in Minnesota, widely scattered, but mostly in the SE Quadrant. In North America it is generally found east of the Mississippi River plus Texas, New Mexico, Oklahoma, Kansas and Calif. In Canada it is known in Ontario and Quebec.

Varities and Subspecies: There are 10 recognized subspecies and varieties with subspecies in North America. The variety considered native to Minnesota is var. villicaulis (Pennell) E.J. Palmer & Steyerm. It has a more restricted range - east of the Mississippi and west of the Appalachians, not in the gulf states. In Canada it is known in Ontario and Quebec. USDA has a complete list. (Ref. #W2).

The University of Minnesota Herbarium lists three species of Monarda found in Minnesota; besides M. punctata, the other two are two varieties of Wild Bergamot, Monarda fistulosa L. var. fistulosa, and var. menthaefolia. and M. didyma, Scarlet Beebalm, although the DNR does not have a location for it currently and it is probably no longer in the state.

Medicinal Lore: Oleum Monardae or Oil of Horsemint was listed officially in the U.S. for use as medicinal external vesicant. An infusion was sometimes used for colic or as a diuretic in urinary disorders. The active constituent of the plant is an abundant volatile oil which contains thymol, in fact 61% thymol. Thymol is also obtained from the Thyme plant and is an important commercial product of that plant. See Mrs. Grieve (Ref. #7) for more details.

References and site links

References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.

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