Isanthus brachiatus (False Pennyroyal)

Plant Info
Also known as: Fluxweed
Genus:Isanthus
Family:Lamiaceae (Mint)
Life cycle:annual
Origin:native
Habitat:sun; dry prairies, rock outcrops, barrens
Bloom season:August - September
Plant height:8 to 16 inches
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 5-petals Flower shape: tubular

[photo of flower] 1 to 3 flowers on 3/8-inch stalks arising from leaf axils in the upper plant. Flowers are about ¼ inch across, pinkish to blue, with 5 spreading, oblong petals, one slightly longer than the others and often bent downwards. 4 slender stamens with dark purple tips protrude from the center.

[photo of calyx] The petals are fused at the base into a tube that is contained within the calyx, which has 5 narrowly triangular, sharply pointed lobes as long as or a little longer than the petals and are hairy on the outer surface. A pair of tiny, leafy bracts is at the base of the calyx.

Leaves and stems: Leaf attachment: opposite Leaf type: simple

[photo of leaves] Leaves are about 1 inch long and 1/3 inch wide, toothless, minutely hairy, lance-elliptic with a pointed tip and tapering at the base to a short stalk. Attachment is opposite, with pairs at right angles to the pair above and below. Stems are branched, 4-sided, minutely hairy, glandular in the upper plant.

Fruit: Fruit type: seed without plume

[photo of fruit] Fruit is set of 4 nutlets, each containing a single seed.

Notes:

False Pennyroyal is a small statured plant that you don't come across often, but it is fairly common in its habitat. It's habitat is at risk, however, from bedrock mining and invasive species. It is not considered rare, but will probably diminish over time. It is known as Trichostema brachiatum in some references

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More photos

Photos by K. Chayka and Peter M. Dziuk taken at a rock outcrop in Stearns County.

Comments

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