Plants and Soils of the Walnut Wetlands

Visitors: Use the links above to learn more about specific aspects of the Walnut Wetlands.

Overview image of the Northern Floodplain.

Northern Floodplain

The northern floodplain of Walnut Creek between Garner Road and State Street is described as an alluvial forest because it lies in the floodplain of Walnut Creek. Each time Walnut Creek floods above its banks soil and sand particles wash into the flood plain, creating a unique habitat for plants and animals.

Walnut Creek and floodplain looking east (left photo); floodplain interior (right).

The most common types of trees that grow in floodplain areas are bottomland hardwoods. These are deciduous trees, including many oaks that have very dense wood. A silhouette of Water Oak, Quercus nigra, on floodplain is seen below. The leaves and bark of water oak are helpful for identification.

Water oak silhouette (left); water oak leaves and bark (right).

Swamp Chestnut Oak, Quercus michauxii, has bark similar to the common white oak that grows in drier soils. However, its leaf shape is quite different.

Swamp chestnut oak bark (left); swamp chestnut oak leaves (right).

Sycamore, Platanus occidentalus, known by its white and peeling bark, is also found on the Walnut Creek floodplain.

Sycamore bark (left and right).

The seeds of Box Elder, Acer negundo, are easy to identify due to their large size and winged structure.

<Box Elder seeds

One problem that occurs in urban natural areas is that non-native plant seeds are carried into areas where they grow easily and out compete native plants. The northern flood plain has extensive patches of Chinese Privet, Ligustrum sinense, whose seed was likely carried here from yard plantings. Some exotic species become very invasive and can destroy native plant populations. In the photo below an invasive ground cover has spread over a large area. Even though it looks nice and green it will keep native wildflowers from growing by not allowing them to get enough sunlight, water and nutrients.

Chinese privet (left); invasive ground cover (right).

Invasive vines are also very prominent in the northern floodplain . The close up below shows how invasive vines can smother a tree.

Invasive vines (left); invasive close-up (right).

Even in the early winter there are many beautiful things to see on the Walnut Creek floodplain. Look closely at fallen logs and you might find colorful poisonous mushrooms or fungi that seem dance along rotting bark.

Poisonous Orange mushrooms (left); white fungi (right).

The wild rosebush makes travelers weary of its prickles but happy to see is brilliant fall leaf color. In the fall the tributary streams of Walnut Creek run clear as long as we keep them clean and free of trash.

Wildrose bush (left); walnut creek tributary (right).

Many animals live in the northern floodplain along Walnut Creek. A small pond created by a fallen tree provides habitat for frogs, salamanders and a water source for mammals and birds. This lush meadow of sedges and grasses inside the flood plain forest provides food for many animals.

Small pond formed from treefall (left); meadow of sedges and grasses (right).

After browsing on grass, a white tailed deer left its footprint in the mud.

<Deer tracks in floodplain mud.