Identify Your SAV Maryland Dept of Natural Resources
  DNR Home
Coontail, Hornwort
Ceratophyllym demersum

Native to Chesapeake Bay

  • Family - Ceratophyllaceae
     
  • Distribution - Coontail usually grows in freshwater reaches of tributaries with moderate to high nutrient concentrations and can be found to depths of 2 meters. It is also found in some lower salinity tidal areas (e.g., the Middle River, the Potomac River near Alexandria, and Lake Placid on the Magothy River). It is fragile and limited to slow moving water in streams and ponds. It can also be found in the interior of large beds comprised of other bay grass species. Unlike other bay grass, coontail has no true roots and is free-floating, and therefore does not require any particular substrate, but instead absorbs nutrients from the water column.
     
  • Recognition - Coontail, because it has no true roots, may float in dense mats beneath the water surface and is only occasionally attached to the sediment by its basal ends. Coontail has slender, densely branched stems of up to 2.5 m (9 ft) in length. The compound leaves of coontail are divided or forked into linear and flattened segments 1 cm to 3.5 cm (2/5 in to 1 3/5 in) long with fine teeth on one side of the leaf margin. Leaves have a stiff and brittle texture and grow in whorls of 9 to 10 at each stem node with whorls becoming more crowded towards the stem tips.
     
  • Ecological Significance - Coontail is found in all 50 states and Puerto Rico. Unlike the other bay grass found in the Chesapeake Bay, coontail has no true roots and obtains all its nutrients directly from the water column. It is very shade tolerant and can form large, dense mats in tidal freshwater tributaries of the bay and in slow-moving streams and ponds.
     
  • Similar Species - Eurasian watermilfoil (Myriophyllum spicatum) has roots and pinnate leaves and is very different in form from coontail, appearing more feathery and limp when held out of the water.
     
  • Reproduction - Coontail reproduces asexually (vegetatively) and sexually (by seed). Stem fragments with lateral buds develop into new plants throughout the season. In autumn stem tips break off and over-winter on the bottom before sprouting in spring. Occasional sexual reproduction produces small purple flower clusters between July and September, followed by a single nut-like seed. Shade-tolerance and its floating habit make turbidity less of a limiting factor for coontail than for other bay grasses.

Print out a copy for the field
(Adobe Acrobat file 82KB) - To get the free
Acrobat Reader go to Adobe.com.

If you don't think your plant is represented above try going back a level and choosing again.

Detail view of Coontail Detail view of Coontail Detail view of Coontail Detail view of Coontail

DNR Home > Bays & Streams > Bay Grass Home > Bay Grass Identification
Email us with questions, comments, and suggestions
   Copyright 1995-2010 Maryland Department of Natural Resources 1-877-620-8DNR (8367)
DNR Privacy Policy