TREE OF THE MONTH - MAY 2017 DOVE TREE

Image CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=261697

The Dove tree (Davidia involucrata) is a spectacular tree that you don't see very often, but is not so rare that you won't find one growing in larger collections or in the gardens of the aristocracy-come-National-Trust somewhere within reach. I think I saw my first at Heligan in Cornwall but am now lucky to have two closer to home at Deans Court and Canford School, Wimborne. But I have only once encountered one in a smaller private garden, in Lyndhurst, in the course of my work, but what a surprise and a treat it was. When in flower, they attract the attention of even those that are  least interested in trees or horticulture. If you come across one in a public place flowering in May, the chances are that there will be several others looking at it at the same time, and if you eavesdrop on their conversations, you will probably hear them expressing wonderment at its beauty, and puzzlement at what on earth it could be - at least that's been my experience.

Image By Larske (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html)

The feature attracting all the attention is, of course, the multitude of huge flowers. Or to be precise, they are the modified leaves, or bracts, attached to the flowers - just like the red bracts of the Poinsettias you often see sold at Christmas. On the Dove tree these leaves have evolved into a white or cream colour to help attract pollinating insects to the relatively inconspicuous  globular head of small yellow flowers. There are two bracts to each flower, one being somewhat larger and up to 8 inches long, the other about half as long. The name 'Dove tree' is clearly derived from the resemblance to doves perched in the tree. Other names commonly used are 'Handkerchief tree' and 'Ghost tree' for obvious reasons.

To protect the bracts, Dove trees should not be placed in an exposed location. They are also susceptible to drought and can be damaged by a late spring frost. They perform best on a good loamy soil and can reach 15-20m. To get maximum impact from the flowers it really needs to be grown as an isolated specimen in plenty of space so that it can spread to its full potential and you can walk around it, admiring it from all sides. There is a little wait between planting and flowering - often five to ten years. The fruit that develop are round and hard - about the size of a walnut.

 Davidia is native to Szechwan and Hupeh in western China and its introduction has a story attached to it that is a little reminiscent of Captain Scott's doomed expedition to be the first to the south pole, only to find that the Norwegian Amunsdson had already been and planted his flag.  The tree was first brought to Europe's attention by a French Jesuit priest, Abbé Jean Pierre Armand David, after whom it is named. David arrived in China as a missionary in 1862 shortly after access was improved following the wars with Britain. A keen amateur botanist, he sent dried specimens and seeds to Paris's Natural History Museum and by the time he returned to France he had recorded 250 new plant species as well as the Giant Panda (he arranged for the capture of one adult bear and its transportation to Paris where, sadly, it soon died).  But the Dove tree seeds sent by David were preserved in formaldehyde rather than germinated.

Père David

As the diversity of China's flora became apparent, it attracted the attention of the Nursery trade and there was considerable interest in obtaining and cultivating the new plants for a lucrative market. The Dove tree itself became almost legendary. Veitch & Sons Nurseries, based in Chelsea and Exeter, were one of the largest in Europe, and in 1899 they dispatched an untraveled 23 year old Ernest 'Chinese' Wilson to China to find the Dove tree. His employer's instruction was to 'stick to the one thing you are after and don't spend time and money wandering about'. Wilson sailed to America and on to Hong Kong where an outbreak of bubonic plague prevented any Chinese from leaving and he had to continue to Hanoi without an interpreter. After another 1000 mile journey into China, he met Scottish plantsman Augustine Henry who gave him directions to the location of a Dove tree. This amounted to a crude map on a scrap of paper depicting an area the size of Britain. On this map he indicated the location of a single tree.

Wilson's houseboat. Image By ralph repo [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

Wilson assembled a team including an opium addicted guide, an interpreter and porters. He hired a houseboat and set off in April 1900 to find the X on Henry's map. Incredibly, he was to find it, having travelled 13,000 miles, dodged plague and malaria, passed through hostile country at the time of the Boxer Revolt, and survived being  boat-wrecked in rapids when  he nearly drowned. But all that was left of the tree when he got there was its stump; the timber now formed part of newly built house nearby.  If he knew any swear words, Wilson must surely have used them, but he only records that 'I did not sleep during the night of April 25th 1900'.

But fortune was to smile upon Wilson. He retreated to Ichang where, on 19th May while clambering through some woods, he chanced upon a Dove tree in full flower.

Wilson must have been jubilant, but again his notes are measured, describing the tree as 'at once the most interesting and beautiful of the north temperate flora...their bracts...when stirred by the slightest breeze resemble huge butterflies'. He collected the seeds and returned to England in 1902 where his delighted employers awarded him a gold watch.

But their celebrations were premature, for it turned out that, merde, another French missionary, Guillaume Farges, had in fact returned to France five years earlier, in 1897, with some seeds, one of which had germinated in 1899 at the Vilmorin nursery. The plant flourished and flowered for the first time in 1906. Veitch Nursery was denied the 'introduced by' kudos, and Wilson had found his Amundson's flag. Or had he....

Ernest 'Chinese' Wilson

Veitch Nurseries were to become more despondent as none of Wilson's seeds were germinating  and they were discarded. But this was because they needed up to 18 months of stratification to stimulate growth and seedlings were later found germinating on a compost heap. According to Wilson, 'several hundreds' were raised compared to about 13000 produced at the Vilmorin nursery in France who had received a further consignment of seeds. What's more, a subtle difference between the Veitch and Vilmorin trees was to become apparent. The upper surface of the leaves from Wilson's trees were furnished with silky hairs and the underside felted with a thick grey down (strangely, this hairiness takes about seven years to manifest). The leaves of the Vilmorin trees, on the other hand, remained glabrous, apart from some hairiness of the veins, into maturity. Wilson's form of trees would become known as 'the type' - Davidia involuctrata, and Vilmorin nursery would have only the consolation of introducing a variety of the type - Davidia involucrata var. Vilmoriniana. . Although there is very little difference between them we now know that they differ in chromosome number and there are no hybrid intermediates between the two.

Davidia involucrata var Vilmoriniana at Deans Court, Wimborne. Note the glabrous leaves

The Vilmoriniana variety is commoner in cultivation, presumably because of the greater numbers produced at the time. It is also said to be easier to establish, more vigorous and less vulnerable to late spring frosts.

If you have a suitable location with enough space, and can track a tree down - it really is a tree that should be more commonly planted. The Royal Horticultural Society website lists 51 suppliers and you can search for the closest by entering your postcode at this link:  Click here

Sources:
Bean W J Trees and Shrubs Hardy in the British Isles
Kingsbury N and Jones A; The Splendour of the Tree
Musgrave, T. Gardner, C. & Musgrave, W.  The Plant Hunters, 1998
Johnson H. 1973; Trees