Deciduous Conifers

Every year, by the time autumn comes to a close, thousands of people have walked  around the Pinetum enjoying the fantastic changes in leaf colour on trees like the liquidambars, katsura, maples, birch and sorbus, all beautifully set against  the evergreen conifers. However, most people are unaware that some of the best autumn colour at Bedgebury is actually provided by deciduous conifers.  I was amazed when informed by one  of the foresters that all of the trees by Marshal's Lake are dying! In fact, they  are deciduous conifers and every autumn they lose their ‘leaves’. It is true that the majority of conifers are evergreen and out of the 8 families, 69 genera, 630 species and 180 varieties and subspecies, there are only 5 genera containing 14 species that are deciduous. All are from the northern hemisphere and all genera can be found at Bedgebury.

 

Autumn 09 055

Larix - the larches

The larches are probably the best known of the deciduous conifers. They are found growing in the cooler climate of the temperate northern hemisphere and are one of the dominant species in the huge expanse of boreal forest in Canada and Russia. Most of the larches come from very cold areas and cannot grow in our warmer climate but the species that do are commercially important trees. In autumn, they turn a lovely buttery yellow, but can lose their needles very quickly if the wind gets up.

In the UK the larch is commonly planted across the South of England. The species used are Japanese larch and hybrid larch as these have a higher timber  yield than European larch. In 2009, Phytophthora ramorum (Sudden Oak Death) was unexpectedly found infecting and killing large numbers of Japanese larch trees (Larix kaempferi) in south-west England. This was the first time it had  ever been found anywhere in the world and caused lethal infection (in the form  of stem cankers) on a commercially important conifer species.

Pseudolarix amabilis - golden larch

The name for this beautiful tree translates into pseudo meaning false, larix meaning larch and amabilis meaning loveable which I think is very apt! Although this tree is commonly known as the golden larch, it is more closely related to abies and cedars. It is both rare in cultivation and  in its native habitat of eastern China.  The bright green needles turn a beautiful golden yellow in autumn, hence the common name. Look out for the distinctive cones that resemble globe artichokes.

At Bedgebury, we have two 60 year old trees that are growing slowly and are unlikely to reach more than 15m. However I was lucky enough to see towering mature specimens in the wild at Tianmu Shan in Eastern China in 2010.

Taxodium - swamp cypress

The swamp cypresses are only found  in South East USA, Mexico and just into Guatemala. They are remarkable for their ability to grow in very wet areas. They also produce strange ‘knees’ called pneumatophores but the function of these isn’t really known yet. Some think it is to help get oxygen to the trees roots but it is more likely that it helps in stabilising the trees in swampy wet ground, such as mangrove swamps.

The Mexican swamp cypress is the national tree of Mexico and can become a very large tree; there is a famous tree in a church yard in Oaxaca in Mexico that has a circumference of 36m! The young trees we planted in 2005 have some way to go before they get anywhere near this size!

There is an amazing group of swamp cypress on the east side of Marshal's Lake. These were all planted in 1925 and now provide a blaze of vibrant reds and browns in autumn. In 2006, I was lucky enough to take part in a seed collecting expedition to eastern USA, funded by  the Friends. We were able to see these stunning trees in the wild and make valuable seed collections. The seeds  from this trip were propagated in our nursery and are now growing happily  in the Pinetum.

Gylptostrobus pensilis - Chinese water fir

This is the rarest of the deciduous conifers, both in the wild and in cultivation. It is commonly found in  South East  China but whether this is a natural population or a planted one is currently disputed. The only truly wild populations are in Vietnam and Laos and these  are under threat from changes to their habitat. In Vietnam, the few remaining trees are in the middle of a coffee plantation and, in Laos, most of the trees are in an area due to be flooded when  a dam is built.

Glyptostrobus pensilis3

The International Union for the Conservation of Nature lists Glyptostrobus as Critically Endangered and states  that “Given current trends, this species could well become Critically Endangered (possibly “Extinct in the Wild”) in the  near future”. Glytostrobus is related to Taxodium and is usually found in wet ground, alongside streams and rivers  but can grow in up to 60cm of water. In warmer climes, it attains a similar stature to the Taxodiums but in the UK it grows slowly making a small pyramidical tree and turns a lovely orangy bronze colour  in the autumn.

Metasequoia glyptostroboides - dawn redwood

Fossil records show that dawn redwoods once blanketed the northern hemisphere but were thought to be extinct until a chance discovery in a remote rural village in  south central China in 1941. They were introduced to the West in 1947 and arrived at Bedgebury in 1950.

The dawn redwoods superficially resemble the swamp cypress but are easily identifiable by their fluted trunk, shaggy light brown bark, elongated cylindrical cones and pyramid-crown shape. In autumn, the beautiful grass green leaves turn a fantastic pinkish bronze.

Since its discovery, the dawn redwood has been planted extensively all over the world as an ornamental tree, with the most impressive planting in Pizhou City where there is a 60km long avenue with one million trees in it! However, it is listed by the IUCN as critically endangered as there so few trees left in its native habitat.

Former curator of Bedgebury, Chris Reynolds, went to the site of the original discovery in 2008 and reported that the area was now a town and all that remained of the forest were the big trees. Who knows what will become of this majestic tree in the wild?