perilla mint
(Perilla frutescens (L.) Britton)

Overview

Appearance

Perilla frutescens is an erect, annual freely branching herbaceous plant that grows from 1-6.6 ft. (0.3-2 m) tall. The square stems are villose, purple or green with four parallel grooves. Dried stalks can persist through winter. It is native to Eastern Asia.

Foliage

Opposite leaves are membranous or herbaceous, broadly ovate or orbicular, 2.76-5.12 in. long by 1.77-3.94 in. wide (7-13 cm X 4.5-10 cm), with mucronate tips, a rounded or broad cuneate bases, and dentate margins. The pilose surface of the leaves may be green or purple on both sides. Each leaf has seven to eight pairs of lateral veins, which are closer together near the base. The veins on the upper surface are slightly raised, more so on the underside. The petiole is flat and villose.

Flowers

Flowers are held in pairs along the stalk. The inflorescence is a villose corymb that may grow either terminally or from the leaf axils.

Fruit

The sub-globose fruits are reticulate nutlets, grayish-brown, and are about 0.06 in. (1.5 mm) in diameter.

Ecological Threat

P. frutescens grows along roadsides, ditches, forest margins, and on hillsides. It spreads to natural areas, especially disturbed areas. I can disrupt native ecosystems by outcompeting native plants. It is ordinarily avoided by cattle and has been implicated in cattle poisoning. Beefsteak plants are most toxic if cut and dried for hay late in the summer, during seed production.

Resources

• Weed of the Week - USDA Forest Service
• Plant Invaders of Mid-Atlantic Natural Areas - National Park Service

Selected Images

Maps

Invasive Listing Sources

• City of Ann Arbor Michigan Parks and Recreation
• Commonwealth of Pennsylvania, Department of Conservation and Natural Resources, 1994.
• Indiana Invasive Species Council - Invasive Plant List
• Invasive Plant Species of West Virginia
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• Kentucky Exotic Pest Plant Council - Significant Threat
• Maryland Cooperative Extension Service.  2003. Invasive Plant Control in Maryland. Home and Garden Information Center, Home and Garden Mimeo HG88. 4 pp.
• Maryland Department of Natural Resources Policy: Restriction on Planting Exotic Invasive Plants
• Maryland Invasive Species Council - Invasive Species of Concern in Maryland
• Missouri SRISP Species List
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• New Jersey Invasive Species Strike Team 2017 Invasive Species List
• Non-Native Invasive Plants of Arlington County, Virginia
• Non-Native Invasive Plants of the City of Alexandria, Virginia
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• Pennsylvania Department of Conservation and Natural Resources Invasive Plants
• Plant Invaders of Mid-Atlantic Natural Areas
• Tennessee Exotic Pest Plant Council
• Virginia Invasive Plant Species List
• Virginia Master Naturalists Priority Species List
• WeedUS - Database of Plants Invading Natural Areas in the United States
• West Virginia Invasive Species Strategic Plan and Volunteer Guidelines 2014
• West Virginia Native Plant Society, Flora West Virginia Project, and West Virginia Curatorial Database System, September 3, 1999

References