Sign 30 - FOUR LAYERS OF GREEN

Like the tropical forest, the marsh efficiently captures maximum light energy with a complex layering of plant life. No wonder it is so productive of wildlife!

1. A canopy of EMERGENT plants takes its share first:  cattails, bulrushes, arrowheads, bur reed (See sign 2). But their vertical leaves let much light pass through.

2. The FLOATING plants - Duckweeds - often get much of the rest; but - like the canopy plants - they come and go. These sometimes cover the water but are not algal scums. They include the world's smallest flowering plants - Lemna minor and trisulca; Spirodela; Wolffia; and two mosses - Riccia and Ricciocarpus. Eutrophic waters may have algal scums which trap much light. The floating leaves of water lilies and pond weeds can also intercept much light in places.

3. SUBMERGED WATER WEEDS, mostly rooted to the bottom, include nine groups, most of whose flowers are briefly borne above the water: Elodea (waterweed); Myriophyllum (several milfoils); Ceratophyllum (coontail); Ranunculus (water crowfoot); Potomogeton (many pond weeds); Vallisneria (wild celery or ribbongrass); Utricularia (bladderwort); Najas & Zannichellia (bushy and horned pond weeds). These form important hiding places for fish fry as well as food for insects and ducks. Clean open shallow water - where waterweeds get enough light - and a firm bottom for rooting are therefore important for waterfowl and fish spawning. The waterweeds are excluded at present by the siltation occurring here which makes the bottom too soft and the water too turbid (muddy).

4. MICROSCOPIC PLANTS (algae) of hundreds of kinds. A few, like Mougeotia and Spirogyra and Hydrodictyon, form strands or nets visible near the surface, but most are microscopic, single or few-celled, and fall into two groups: The free floating or swimming (plankton algae), and the attached (sessile) algae growing on water­weeds, turtle backs, and sticks and stones in the water. Although they receive only what light is left after passing through the other three layers, these plants are rightly called the "grass of the waters".
   
          Often not visible except in green "soupy" eutrophic waters, the algae supply most of the abundant food base in the marsh. The energy they continually store is quickly "harvested" by small animals from protozoa to water fleas, and the larger "grazers" - tadpoles, snails and caddisflies. Their food then goes to small fish and predatory insects like dragonflies, and finally to larger fish and birds. Upland dwellers - racoon, snakes, hawks, lice, maggots,       flycatchers and decay organisms (fungi and bacteria) - carry the food chain further, still dependent on what is now left of the minute percentage of solar energy that the algae have trapped in their food-making. You can see why muddy water can seriously hinder production all along the line by interrupting the vital light energy and wasting it.