Slender mountain mint

The word 'pycnanthemum' is derived from the Greek word 'pyknos' meaning dense and 'anthos' meaning flower. Altogether it refers to the dense clusters of flower found on this Mountain mint. The specific epithet 'tenuifolium' refers to the leaves, meaning slender or thin leaved.

A quick look at the flowers of Pycnanthemum tenuifolium finds them quite similar to those of P. Virginianum. They are white or pale lavender and usually with purplish dots. The flowers have an upper and lower lip with the lower lip having 3 lobes. While individual flowers are small, their impact is large as they grow in clusters like little bouquets. Flowering extends up to 6 weeks.

After flowering, small dark seeds transition from brown to almost a pewter color when ripe. The ripe seeds are dispersed by wind.

Pycnanthemum tenufolium is a perennial wildflower growing from 2- 3 feet tall. It has numerous branches giving it a bushy appearance. The leaves are linear and occur opposite. They are sessile (or nearly so), narrow, tapering and about 1-3 inches in length.

This mountain mint has a dual root system consisting of both a tap root and rhizomes. The tap root helps sustain it during droughts whereas the rhizomes are key to helping it form colonies. Hence, this mountain mint has the ability to thrive in dry, rocky ground that is more challenging for other Mountain mints. Such a strong root system also makes Pycnanthemum tenufolium a great choice for planting on slopes and areas where erosion is problem.

Pycnanthemum tenuifolium is powerhouse plant when it comes to supporting many kinds of insects including bees, butterflies, skippers, wasps, beetles and flies. Here's a sampling of insects supported by this small Mountain mint!

Butterflies and Skippers

The Zebra Swallowtail is a huge butterfly that is always easy to identify, but it's just one of many butterflies, skippers and other insects that visit these flowers!

Bees and Wasps

Other insects

Slender mountain mint is not very picky about its habitat. It can be found in woodlands, limestone glades, prairies and grasslands, thickets, gravel banks of rivers and bluffs. On Ozarkedge, I find it in glades, woodland edges and grasslands. In fact, this tough native handles the dry, sunny spots where most other plants can't manage.

Pycnanthemum tenuifolium is native to the eastern half of the United States. Although Natureserve gives it an overall ranking of Secure, it is ranked as Critically imperiled in Nebraska (which is at the western edge of its natural range). In Arkansas it has a Conservation value of 6 in the group of 4-7. This indicates "Typically matrix taxa in intact, stable habitats, with some limited ability to respond to destabilizing forces and repopulate areas from which they have been extirpated."

Pycnanthemum tenuifolium is frequently recommended for use in roadside restorations and as a pollinator plant for home gardens. Why?

• flowers support many pollinators and beneficial insects
• easy to grow
• long bloom time
• non-aggressive with other plants
• excellent companion plant
• deer, rabbit, vole resistant