Keeping Up with the Sedges

Author: 
Michael Alcamo
Date: 
03/01/2009
Source: 
Trail Walker

 

   
   

Sedges (genus Carex) present the usual classic paradox of botany and hiking: we walk through them or over them, yet few hikers might be able to point them out.

From a distance, sedges look like their plant cousins, the grasses; however, they have important structural differences. First, a sedge has a clearly defined triangular stem; grasses are usually round. And, looking closer, you'll see that a sedge's leaves are spirally arranged in three ranks, while grasses have alternate leaves in two ranks.

Sedges prefer wet areas and are found either rooted in moist ground or rooted in the sediment of shallow water at the edges of a pond or lake. They are vitally important parts of the ecology of a marsh, bog, or fen.

Sedges are flowering plants-and what flowers they have. For such modest plants, the range of flower structures is quite dramatic and beautiful. The flowering part-or "inflorescence"-is a group of small florets, which may have some missing parts. The "staminate floret," or male portion, is at the top of the structure, and the pistillate florets (female) are beneath. Wind carries the pollen grains to the stigmatic surfaces of female florets on another plant.

The sedge has a fruit, which is a dry achene bearing one seed, which is sometimes enclosed in a perigynium, a small inflated structure.

Once the seed forms, it can remain dormant for quite some time before germinating into a new plant. Generally, the seed will germinate only in the presence of sunlight and temperatures above 10 degrees Celsius.

Sedges reproduce in annual cycles by means of seeds, but are also perennials-at the end of the growing season, they die back to the ground level, and the following year, they will sprout from underground rhizomes or roots. In this way, a sward of sedges might actually be one large organism.

Sedges depend on the wind, not insects, for pollination, though their flowers nevertheless attract insects. Sedge flowers are considered delicacies by sedge grasshoppers, leaf beetles, aphids, billbugs and some plant bugs, caterpillars, and moths. In wetlands, the seeds or seedheads of sedges are food sources for ducks, rails, certain songbirds, small rodents, and some turtles.

There was great excitement in the sedge community recently when the Large-Headed Sedge (Carex macrocephala) was discovered in New Jersey. This sedge is native to Russia, Japan, and the Pacific coast of Canada. In summer 2005, New Jersey botanist Louise Wootton discovered three populations growing in a coastal area of the state. Professor Wootton hypothesized that dried sedges had been used as shipping material, and that a few grains had blown into the wind when someone in New Jersey opened a box of something made in Japan many years ago.

Many sedges are listed as endangered or threatened in New York and New Jersey, so unless you know that a species is very common, it's better to enjoy them from a distance, and to let them continue to live their placid sedge lives.

 

Michael Alcamo is a writer and naturalist and a member of ADK's Mid-Hudson Chapter as well as the Trail Conference.