The Edges of Water: A Beginner's Guide to Pond and Stream Plants

Water changes everything. The plants that grow at the edge of a pond or along a slow stream are different from the ones in the meadow behind them, and they are often easier to identify because their shapes are so unusual. Once you learn a few of them, a walk along any wetland becomes a series of small recognitions, like greeting old friends in a crowded room.

The first thing to notice is where the plant is standing. Some plants grow in the water itself, with leaves floating on the surface. Some grow in the mud at the water's edge, with their roots in saturated soil. Others grow just beyond the water line, in ground that is damp but not flooded. This gradient is the key to the whole habitat. If you can describe where a plant is growing, you have already narrowed the field considerably.

Floating Leaves and Emergent Stalks

Among the floating plants, water lilies are the classic example. Their leaves are large, flat, and notched like a heart, and they rest on the surface with the stem attached underneath. The flowers are unmistakable, but even without them, the leaf shape and the way it sits on the water are enough. Smaller floating plants like duckweed form a green film on still water, each plant a tiny dot with a single root hanging below. It is worth looking at duckweed through a hand lens, because the simplicity of it is oddly beautiful.

Emergent plants are the ones that stand up out of the water, and they are the easiest to see from shore. Cattails are the most familiar, with their tall strap-like leaves and distinctive brown seed heads. Less known but just as common are the rushes and sedges, which look like grasses but are not. A simple rule helps here: grasses have round, hollow stems; sedges have triangular, solid stems. If you roll a stem between your fingers and feel three distinct edges, you are holding a sedge. Rushes have round stems too, but they are solid rather than hollow, and their flowers are usually small and brown or green.

The Damp Ground Beyond the Water

Step back from the water and you enter the zone of damp-soil plants. This is where jewelweed grows, with its succulent translucent stems and orange or yellow flowers shaped like tiny trumpets. Touch a ripe seed pod and it will explode in your hand, a trick that never gets old. Here too you will find forget-me-nots, with their small blue flowers and hairy leaves, and the tall purple spikes of purple loosestrife, a plant that has spread far beyond its native range in many places.

I like to visit the same wetland edge through the seasons, because the cast of characters changes. Spring brings the first green shoots pushing up through last year's dead stems. Summer is the full chorus, with flowers and insects everywhere. Fall brings seed heads and changing colors, and winter strips it all back to stems and silhouettes, which is actually a wonderful time to learn the shapes of things without the distraction of leaves. Each visit adds a layer to the picture, and the edge of the water slowly becomes a place I know rather than a place I pass through.