Bald Cypress Adaptations

Bald cypress trees survive in seasonally flood soils and in drier, upland sites.

A non-flowering tree that produces its seeds in cones, the bald cypress (Taxodium distichum) naturally inhabits the lowland plains across the southeastern United States. Horticulturists prize this tree for its attractive habit, adaptability to both soggy and drier average garden soils and its attractive, feathery foliage. Bald cypress developed multiple biological adaptations to improve its survival in the wild. These adaptations allow the trees to grow well in a wide array of landscape settings, and often contribute to the tree's ornamental qualities.

Foliage Insight

Although a conifer, bald cypress does not retain its needle foliage year round like most other conifers. Instead of risking dehydration over the winter by retaining its leaves, the bald cypress sheds it needles in the progressively colder weeks of autumn or early winter. The normally bright green, soft needles turn attractive shades of rusty orange anytime from October to January across the Southeast, after frosts occur. Excessive drought also causes the foliage to turn orange and drop off, conserving moisture. The trees enter a dormancy until temperatures or soil moisture is more conducive for growth.

Root Structure

Bald cypress trees are naturally broad-rooted and resist toppling from strong winds. When growing in soggy soils or in seasonally flooded areas with shallow water, bald cypress trees develop spirelike protrusions from the ground called "knees." There is uncertainty as to the purpose of these knees. Traditionally, it was believed that knees are a means of gas exchange from roots that are saturated underwater. This has proven to be untrue, as trees that had their knees physically removed suffered no ill consequences, according to Gerald Klingaman of the University of Arkansas. However, concentrated masses of roots grown from knees potentially increase the anchorage and steadfastness of bald cypress trees in softer, wetter soils.

Reproduction

A bald cypress tree is pollinated by the wind, as both male and female cones appear annually in spring. The female cones yield seeds, which are shed to the soil below, but disseminated most effectively by water. Seeds sprout in saturated soil, but not flooded water, after a period of one to three months. Seeds covered by water may rot, but some seeds survive and may germinate up to 30 months later once flood waters subside and the soil is exposed but warm and mucky. Growth of seedlings must initially be rapid to avoid being fully overtaken by increasing seasonal flood water depths.

Soil Considerations

While the native habitat of the bald cypress is in mucky lowland swamps with an acidic to neutral pH, this tree survives in many other growing conditions. Once the seedling establishes and develops a strong root system, bald cypress trees demonstrate considerable drought tolerance. This allows trees to survive droughts on river banks as well as on average garden soils not near permanent bodies of freshwater. Irrigation promotes growth, but the bald cypress will survive as long as a minimum of 30 inches of natural precipitation or irrigation occurs annually.

References

• U.S. Forest Service: Baldcypress
• University of Arkansas Cooperative Extension: Bald Cypress

Resources

• Learn2Grow: Taxodium Distichum