02 Apr What Tree? Dawn Redwood
Dawn Redwood (Metasequoia glyptostroboides)
Following on from last month’s What Tree we found it only right that we take a closer look at the Dawn Redwood. Up until the mid forties it was thought that this species was extinct, known only from Mesozoic Era fossil samples. Sixty million years ago in the Arctic region this particular conifer had thrived by becoming deciduous, losing all of its needles during the long lightless winter in order to conserve energy, and then growing vigorously in the bright light of summer. It spread successfully across North America and Eurasia until the arrival of the Ice Age, which seemingly marked the end of it. However it was rediscovered in a remote valley in south-western China in 1941 – here local villagers revered the shui-shan (‘water fir’) and built shrines beneath them. Seeds were collected and distributed to arboretums and botanic gardens worldwide and it has once again thrived.
Whilst it can be planted as a single specimen, this species looks particularly impressive when grown as a row or an avenue, with the best example of this being the 47km long Dawn Redwood Avenue in Pizhou, Jiangsu in China. This was the vision of a Parks Manager called Qingxi Li, who started planting it in 1975; a million trees later his vision was complete.
The first dawn redwood to be planted in the UK came from seeds sent from China to Cambridge University Botanic Garden in the 1940s, and since then they have spread across the country, preferring the more humid western regions.
It is monoecious, producing flowers of both sexes in the early spring, and is pollinated by the wind. Small spherical-ovoid cones mature about 8-9 months after pollination.
Appearance and Identification
This vigorously growing conifer has a perfectly vertical main trunk with fibrous, orange-brown bark, from which branches grow in a regular pattern. This creates a pleasing conical shape to the tree. It tends to grow to heights of around 25-35m tall although in its native China it has been known to reach heights of about 50m. Its foliage is feathery in appearance and unusually for a conifer this species is deciduous – its leaves turn tawny brown before it drops them in the autumn.
The narrow, conical crown of the dawn redwood becomes broader as the tree matures, reaching widths of around 10m.
Young twigs are reddish brown and slant upwards, flattening out to almost horizontal with age. The bright green needle-like leaves are held in two opposing ranks (unlike Swamp Cypress with alternate ranks) which give them their feathery appearance, and they turn to bronze/orange brown in autumn.
Comparison between swamp cypress and dawn redwood
The trunk of mature trees becomes knotted to form wide buttresses at the bottom, and the bark gradually forms vertical fissures causing it to flake off in long strips.
Dawn Redwood Bark
Propagation and Control
The dawn redwood propogates easily from cuttings and grows well in moist, well-drained soils and can also tolerate standing water, but it likes full sun and does not grow well in the shade.
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.