Overview

M. keisak is native to temperate and tropical Asia and was accidentally introduced into the United States, in South Carolina, around 1935 as a weed in rice crops. It is found in the southeastern and northwestern United States.

Appearance

Murdannia keisak is an annual, emergent plant that invades wetlands and agricultural crops, such as rice. Plant stems are succulent, form roots at the nodes, and grow prostrate along the ground. Stems are 12-30 in. (30.5-76.2 cm) long.  Plants can reproduce vegetatively from stem fragments.

Foliage

Leaves are alternate, lance-shaped, lack a petiole, and up to 3 in. (7.6 cm) long. The leaf sheath surrounds the plant stem and is pubescent along the margins.

Flowers

Flowering occur during the Fall. Small, pink, 3-petaled flowers occur singly or in small clusters at the apex of the stems and in the leaf axils. Three green sepals are reflexed when the flower is open.

Fruit

The fruit is a capsule that contains several small seeds.

Ecological Threat

M. keisak invades water edges, wetlands, ponds, marshes, and ditches and often grows immersed. It forms dense mats that out-compete native vegetation and act as a weed in rice crops. It can be used as an aquarium or water feature plant. Seeds can be eaten and spread by waterfowl.

Resources

• Invasive Alien Plant Species of Virginia - Virginia DCR and Virginia Native Plant Society
• Plant Invaders of Mid-Atlantic Natural Areas - National Park Service and U.S. Fish and Wildlife Service

Selected Images

Maps

Invasive Listing Sources

• Alabama Invasive Plant Council
• Delaware Invasive Species Council
• Delaware Invasive Species Council Invasive Species List
• Georgia Exotic Pest Plant Council - Category 1
• Invasive Plant Species of West Virginia
• Invasive Species of Concern in Georgia
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• Jil Swearingen, personal communication, 2009-2017
• Maryland Aquatic Nuisance Species Plan
• Maryland Department of Natural Resources Policy: Restriction on Planting Exotic Invasive Plants
• Maryland Invasive Species Council - Invasive Species of Concern in Maryland
• Mid-Atlantic Field Guide to Aquatic Invasive Species
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• New Jersey Invasive Species Strike Team 2017 Invasive Species List
• New York Regulated and Prohibited Invasive Species - Prohibited
• 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
• Plant Invaders of Mid-Atlantic Natural Areas
• South Carolina Exotic Pest Plant Council
• Tennessee Exotic Pest Plant Council
• Virginia Invasive Plant Species List
• WeedUS - Database of Plants Invading Natural Areas in the United States
• West Virginia Native Plant Society, Flora West Virginia Project, and West Virginia Curatorial Database System, September 3, 1999

References