Ponds

There are over 200 species of spikerush found throughout the world with about 25 of them common to the eastern United States. Spikerushes are usually perennials although some annuals are found. Normally they grow in the mud along a pond or drainage canal bank, or in the shallow water regions of a pond or lake margin. Spikerushes are usually considered an emergent plant, but some species may spend their entire life completely submersed under clear shallow waters up to six feet deep.

There are several species of milfoil and it is often difficult to tell them apart without the flowers or seeds. Almost all of the water milfoils have limp dissected featherlike whorled (some arc alternate) leaves which radiate from a hollow stem. The flowers are tiny and inconspicuous and are usually present from July through September. Light yellow to brownish in color, they are frequently surrounded by broad undissected axils (bracts) which occur in terminal spikes above the water's surface. Reproduction is by seeds, rhizomes and plant fragments. Water milfoil is sometimes confused with coontail (Ceratophyllum species). However, coontail has teeth or serrations on the leaflets, whereas water milfoil's leaflets are smooth. Also, in water milfoil the leaves radiate from the central stem only and the plant has a root system.

Pennyworts, especially water pennywort, are commonly found in Maryland aquatic environments. Not as prevelant as marsh pennywort (H. umbellata), both pennyworts are succulent perennials that are members of the parsley family and native to America. Generally rooted in the mud along pond and ditch banks, they can form dense mats that float on the surface. These mats can actually break away from their roots and continue living and growing while free floating. The mats can also support other plants such as smart weeds, beggar-ticks, or alligator-weed. The mats may grow to such a density that they may impede waterflow in drainage canals and ditches, which can affect irrigation. Often, a variety of submersed aquatic plants may be found entangled among the roots. Many species of Hydrocotyle can grow well in either an aquatic or terrestrial habitat.

Water stargrass obviously derived its name from its conspicuous, pale-yellow, starshaped flower that protrudes above the water's surface when in bloom. Also known as mud plantain, water stargrass has small, linear leaves 2 to 4 inches long and less than 1 / 4 inch wide. The plant is a perennial usually firmly rooted in the sediment and, when given the opportunity, can develop into dense, but patchy beds.

Water wool, or "green cotton-ball algae" as it is sometimes called, can cause tremendous problems in freshwater ponds. It is commonly found around small ponds, slowmoving streams, and canals. Water wool algae usually become a problem in summer when dense growth can interfere with fishing, deplete oxygen, provide a favorable mosquito breeding site, and give the water an undesirable color. Heavily infested ponds can remain a problem throughout the year, especially if the fall and winter months are mild.

As a group, watermeal has the distinction of being one of the world's smallest flowering plants. A member of the duckweed family, watermeal is a free-floating plant that is hardly visible to the naked eye. It is rootless and floats with only its dorsal surface breaking the water surface. Normally growing in association with other duckweeds, it is capable of survival in damp vegetation found along the edges of ponds or sloughs.

White or fragrant water lily (Nymphaea odorata) is often found in ornamental ponds or small ponds for the purpose of esthetics. However, if uncontrolled, the plant can take over a pond and completely cut off the surface, making recreational use difficult. White water lilies do have some value as a wildlife food source: white-tailed deer eat both leaves and stems, and wood ducks are sometimes seen feeding on the plant; many rodents, in particular muskrats, feed on the roots and leaves. The underside of leaves often serve as a site for aquatic insects to lay their eggs.

Widgeon grass, or ditch grass as it is also known, is another one of the more important submersed aquatic vegetations found in Maryland. It is important to wildlife and waterfowl as a food source and as a protective cover and nursery area for small fish and invertebrates. The plant tolerates a wide range of salinity and can be found from almost full strength saline water to shallow brackish water ponds, rivers, and estuaries. It is one of the few species of submersed aquatic vegetation that thrives in alkaline waters. The plant is also tolerant to cool weather and grows well during the fall months.

Known as wild celery, tapegrass, or freshwater eelgrass, Vallisneria americana is one of the most important submersed aquatic vegetations found in Maryland, especially in the Chesapeake Bay. It is one of the most familiar and important waterfowl foods found in this region and occurs in both freshwater ponds and the lower salinity areas of the Bay. It is one of the species of plants that used to have extensive beds in the Susquehanna Flats in the upper portion of the Chesapeake Bay.

At least two different species of arrowhead occur in Maryland, the coastal arrowhead (Sagittaria graminea) and the common arrowhead (S. latifolia). Both are perennial herbs, both emerge from the water and can reach 5 feet, and both have above-water leaves. Coastal arrowhead often has underwater leaves, especially the young plant which is narrow and stalkless and found in clumps. The leaves of common arrowhead are usually shaped like arrow heads.