Last month I "trashed" water hyacinths with insults like "the purple plague" and "one of the worst things that could happen to a fishery."

Add another black mark to water hyacinths - some biologists now think that water hyacinth mats may provide a substrate for yet another invasive plant, a grass-like sedge, that is now causing access problems in several pools on the Tenn-Tom Waterway.

But after bad-mouthing one aquatic plant, it's time to talk about the good side of aquatic vegetation.

Except for water hyacinths and a few other non-native plants that grow to nuisance levels, aquatic vegetation is one of the best things that can happen to a lake and its bass population. Aquatic plants benefit the aquatic ecosystem, fish populations and anglers.

A better ecosystem

Aquatic plants root in the bottom and stabilize the sediment. This reduces sediment resuspension from waves, boat traffic, or water flow. Aquatic plants growing near the shore not only stabilize the bottom but dampen waves. Together, this substantially reduces bank erosion. And unlike expensive bulkheads and rip rap, the aquatic plants are free, self-maintaining and provide better fish habitat.

Aquatic plants produce oxygen needed by all living organisms in the lake. In most lakes, the phytoplankton - algae suspended in the water - produce most of the oxygen, but rooted plants in moderate amounts make a positive contribution to the oxygen budget.

Aquatic plants take up nutrients and minimize algae blooms. They also filter suspended sediments from the water. Together, this makes for clearer water.

Aquatic plants provide expansive surface area, or substrate, for many microorganisms and aquatic invertebrates that are part of the food web leading to fish. Aquatic plants growing from a square yard of lake bottom can support up to 100 times more aquatic invertebrates than a square yard of barren lake bottom.

Everything else being equal, a lake with a moderate amount of aquatic plants will support more pounds of fish than the same lake without plants.

Good for fish

Fish benefit from the improvements in the aquatic ecosystem, especially the abundant food organisms that live on the aquatic plants. But there are direct benefits to fish, too.

The plants provide shelter and refuge from predation for young stages of many fishes. At the same time, they provide cover, or camouflage, for bass and other large predators.

I'm sure you've heard or read that plants provide shade and cooler water temperatures. This is true but not really a big deal, because fish can just move to a little deeper water and achieve the same comforts. But aquatic plants give fish shade, cooler water and cover in shallow water.

Good for anglers

Just as fish are benefited by a healthier and more productive aquatic ecosystem, anything that benefits fish helps anglers. But in addition to healthier fish populations, there are at least four ways aquatic vegetation helps anglers.

First, the aquatic plants concentrate fish. The abundant invertebrates on the plants provide an all-you-can-eat buffet that attracts platoons of sunfish and minnows. And the forage attracts bass.

Second, areas of aquatic plants usually are easy to find. Emergent vegetation, like water willow, or floating-leaf plants, like lotus, spatterdock or water lily, are easy to spot. These plants all hold bass. Yes, deep vegetation may be hard to find in the spring without a good depth finder, but when I go to a new lake, it's a lot easier to find weed beds than brushpiles, submerged stump fields or shell beds.

Third, aquatic plants provide an all-day shallow-water bite. Few aquatic plants grow in water deeper than 15 feet, and most grow in water 10-feet deep or less. I'll spend all day dragging a Carolina rig or pitching a drop shot in 20 to 30 feet of water if I have to, but I would rather fish shallower. I think most anglers will agree that they are more efficient fishing visible cover in shallower water.

Some of you may disagagree, but my fourth reason why vegetation benefits the angler is that fish can be caught so many different ways. Aquatic plants create a shallow bite, and the list of lures that are effective in 10 feet of water or less is far longer than the list for fishing in 20+ feet of water.

Aquatic plants clear the water, and that opens up opportunities to use clear-water lures like hard and soft jerkbaits, swimbaits and finesse presentations in addition to lures like jigs, spinnerbaits, wide-wobbling crankbaits and big soft plastics that are effective in more turbid water.

There is one more piece of good news about aquatic vegetation: Fishery managers recognize the manifold benefits of aquatic plants and are making substantial headway establishing the right plants in the right amounts and in the right places.