What Tree? Swamp Cypress

What Tree? Swamp Cypress

Swamp Cypress (Taxodium distichum)

This month we are learning more about the swamp cypress. This is a large, slow-growing and long-living tree, which as the name suggests grows well in wet or water-logged areas. Native to the southeastern United States, it thrives in the UK and is rarely seen in anything other than good health.

The swamp cypress was introduced to Britain by John Tradescant (d. 1638), as recorded by his friend John Parkinson in the Theatrum Botanicum (1640), but the oldest trees of known date are those that grow at Syon House in London, planted a century or so later. The tallest known specimen grows in its native Virginia and is over 44m tall.

These trees are hardy and tough, and can withstand long periods of time in water. They are often used in public spaces and can be planted as groupings, growing well in both full sunlight and partial shade.

Conical in shape, they develop a broad, fibrous trunk which puts out reddish brown branches. Shoots from these carry soft green spreading needles which turn to orange/red/brown before they drop in the autumn. They tend to reach heights of around 30m, growing fairly vigorously at up to 45cm a year.

Appearance and identification

The main trunk of the swamp cypress is very knotty and twists in an anti-clockwise direction. The bark is reddish brown and fibrous, with an interwoven pattern of ridges and furrows.  Its branches form a pyramid shape and produce simple needle-like leaves which it drops each winter.

Swamp cypress

An interesting characteristic is the protruding roots, or ‘cypress knees’, which can attain a height of up to 1m. The function of these distinctive structures is unclear, but they may assist the tree in aerating its roots, reducing erosion, anchoring the tree more firmly in soft or muddy soil, or perhaps a combination of these.

The species is monoecious, producing male and female cones in April with seeds ripening in October. The female cones are globular, green whilst young turning hard and brown as they mature. Each one is made up of 20-30 spirally-arranged scales which bears one or two seeds. At maturity, these scales drop to the ground and the seeds are dispersed by the water in which the tree is standing, or alternatively by wildlife such as squirrels.

The leaves can be confused with that of Dawn Redwood (Metasequoia glyptostroboides), but can be distinguished by alternate shoots and leaflets, rather than opposite pairs.

Comparison between swamp cypress and dawn redwood

Propagation and control

The swamp cypress can adapt to a wide range of soil types – wet, salty, dry, swampy – however it grows best in wet or well-drained soil. It will grow in full sunlight or partial shade and can tolerate atmospheric pollution.

The main cause of damage is via a fungus called Lauriliella taxodi which attacks the heartwood from the crown to the roots, causing the wood to rot into what is known as ‘pecky cypress’.  In some cases this can be lethal for the tree. Other damaging agents include the cypress flea beetle which destroys the leaves, cones and bark.

Source and Reference Materials

Information detailed in this post has been obtained from the author’s own knowledge and photographic library where possible. Additional source of information and photographs include:

Van den Berk, B.V. (2004). Van den Berk on Trees. Van den Berk Nurseries.

Oregon State University