Dinosaurs from China

For a long time, these fossil conifers were considered to be extinct.

Dawn redwood was first described in 1941 by the fossil records of its leaves and cones. In the same year, the Chinese scientist T.Kan  discovered a stand of unfamiliar trees with reddish bark, growing in one of the provinces of China. The botanist could not identify the genus and species, since the trees were leafless, it being winter. Local people called these trees ‘shuisa‘, or water firs. Although they were fascinatingly exotic and beautiful to the botanist, his attempts to identify the trees were fruitless. Three years later, another botanist T.Van brought back specimens of leaves, bark and cones of the tree, and initially it was ascribed to the genus Glyptostrobus. Because of its likeness to the latter genus, the Chinese or dawn redwood was later named Metasequoia glyptostroboides. The tree has many qualities, which make it similar both to deciduous and evergreen conifers.

The dawn redwoods, growing and bearing cones in China, created great excitement in the botanical world, since they were thought to have disappeared along with the dinosours. In ancient times, these conifers were common throughout moist forests and swamps of Asia, North America and Greenland.

By 1947, seeds and plants collected in China, have been distributed to botanical gardens all over the world. They germinated well, the seedlings matured fast and started flowering in the fifth year. Taken cuttings rooted easily, as well. The first 5 years old seedling produced viable seeds in Nikitsky Botanical Garden (Crimea) in 1956, and two years later the dawn redwood seedlings produced seeds in Great Britain. By 1976 these trees attained height of 20 metres, with the buttressed trunks 2 metres across.

An interesting detail is that seedlings first produce female flowers, while the pollen-bearing cones appear only a couple years later. Currently dawn redwoods are widely planted in France, Great Britain, Poland, Norway, Finland and even Alaska.

The native habitat of the dawn redwood – a small area no larger that 8 sq.km – is in the mountains of China. The largest grove of around 1000 trees grows on the plain of Hubei, which locals have aptly named ‚the plain of water fir‘. Most trees are over 600 years old, standing 30-35 metres tall, and their trunks exceed 2 metres in diametre. They prefer sheltered, damp and shadowy conditions, and mostly grow on river banks, and on the edges of gorges and mixed forests.

The needles of dawn redwood are long and relatively wide, arranged in opposite pairs on the twigs. They are light green in summer, turning copper brown in autumn. Needles are shed before the onset of winter, sometimes still attached to small twigs. Cones are small, 1-1.5 cm in diametre. In favourable conditions the dawn redwood grows fast, and can attain the height of 10 metres in 10 to 15 years.

Several cultivars of garden value:

`National` and `Sheridan Spire` – cultivars with narrow columnar habit.
`Gold Rush` and `Ogon` – needles are yellow, even golden on young plants. A stand of them, which I encountered in France, was truly spectacular.
`Emerald Feathers` –  needles are bright green and flatter than the species.
`White Spot` – needles are streaked in white.

Dawn redwood has proved to be an easy tree to grow in the gardens of climate zones 4 to 8. These plants have already endured a couple of winters in my garden with no setbacks. Recently they have become available in garden centres.

Young dawn redwoods are susceptible to winter damage. Before the winter sets in, mulch young trees thickly and wrap up in horticultural fleece. Mature dawn redwoods withstand severe winter cold, sometimes even down to -32oC. In a prolonged cold spell some twigs freeze and fall off, thus rendering tree less ornamental in subsequent year. If this occurs a few years in a row, the tree might die back. Late spring frosts can scorch young needles.

In North Europe, dawn redwoods are best planted in a sunny and sheltered location. They will tolerate some shade, but not the neighborhood of other trees. They are amenable to most fertile soils, whether sandy or clay, alkaline or acid (pH 4.5), as long as they are well-drained. Rainy, yet warm summers suit dawn redwoods just perfectly. Dawn redwoods are susceptible to heat and drought, therefore require ample watering in dry periods. When watered abundantly, they will grow fast. Fertilise plants in summer with conifer fertiliser, starting a year or two after planting. It is very important to soak the ground well in early winter, especially following a dry autumn.

Seeds of dawn redwood are mostly sterile. Besides, the majority of freshly collected seeds are dormant, and their germination rate is low. They remain viable for 15 years, if kept in an airtight container at 0+5C temperature. The seeds are sown outside in late autumn, 3 to 5cm deep. They should be mulched  with a 1-1.5cm layer of peat, and even thicker in a snowless winter. The next spring seedlings are transplanted into pots or trays, and should be well protected during the next winter. If sown in spring, seeds need to be stratified first in the temperature of 3-5oC. Then they need to be sown into trays and kept warm (18-20oC).

Planted near a water feature or in the Japanese garden, dawn redwood makes a truly magnificent accent plant.

© Giedra Bartas, 2011

One Comment:

  1. A very resourceful description of my favourite tree. Thanks.

Leave a Reply

Your email address will not be published. Required fields are marked *