Classifying water plants
Water plants are most commonly classified by their position in the landscape. Plants that grow in wet or moist soil, or that grow in a few inches to a few feet of water, are called “water plants.” They are then classified by how much water they need, or tolerate, in order to grow. This is the most common method of grouping water plants for hobby gardeners and the one that is used in this book.
Submerged Water Plants Plants that grow entirely underwater are called submerged water plants. They are also called oxygenators for their ability to add oxygen to the water column during daylight hours. Aquatics include the familiar aquarium plants that are grown in children’s goldfish bowls. They also encompass the many underwater plants that provide cover and spawning ground for fish in natural lakes, rivers, and streams.Do not underrate the beauty of submerged plants in the water garden. Many have colorful foliage that glistens underwater, and several even have flowers that float on the water surface during the summer.
They are very easy to grow and need very little care to make their important contribution to the ecology and life of the pond. Floating Water Plants Plants that sit on the water surface with no need of pot or soil are called floating water plants. Floaters are extremely easy to grow and some even flower,with bright blue blooms that start when the weather warms and continue until fall. All they need is a container that holds water, and they will grow right on the deck or patio. Their roots dangle down in the water, drawing nutrients that could otherwise cause an algae bloom. Among the least expensive of all water plants, they are usually bought fresh each year by most water gardeners. In the winter, simply add them to the compost pile or use them to mulch around perennials—because of their high nitrogen content, they add nutrients to the soil even after being removed from the pond.
Marginal Water Plants At the edge of the pond are the “marginals.” These plants grow with their roots in the soil but with most of their foliage above the soil and out of the water. They are also referred to as “emergent” because their leaves emerge above the soil and water. Some grow in soil that is only moist or wet, while others like to be in soil that is a few inches under the water. Marginals can be more than 6 feet or less than 2 inches tall. Some are clump forming and stay where they are put. Others are rambling types that come up all over the pond edge. Both flowers and foliage can range from red to pink, from white to yellow or orange, and even from purple to blue. Fans of variegated foliage will not be disappointed with the selection of striped, blotched, streaked, or margined foliage among the marginal water plants.