Friday, 18 March 2011

Winter-flowering dogwoods


Cornus mas at Westonbirt

Cornus officinalis at Westonbirt



I have always liked the small, rather untidily bushy tree that is Cornus mas. In late winter it bears its clusters of small yellow flowers in a light shimmer across the tree. It is a European species and I've seen it in light woodland on the limestone hills near Prague, flowering in late March: it's always pretty, but not dramatic. It's English name is Cornelian Cherry, on account of the glossy red fruits borne in early autumn. They are rather acidic, but can be used for making jam if you're inclined to waste sugar. There are numerous cultivars, mostly selected for either their flowering or fruiting characteristics (it is is a valued crop in Russia). 'Golden Glory' is a commonly grown clone that we also have at Colesbourne: it is free-flowering, with a more upright branching habit. My favourite is 'Variegata', with very cleanly white-edged leaves and often a heavy crop of fruits. It's only problem is that it's rather slow-growing.

Cornus mas 'Variegata'
Cornus mas has two close relatives in the genus, the very similar-looking C. officinalis from Japan and Korea, and the more distinct Sino-Himalayan C. chinensis. Last week, going round Westonbirt Arboretum with Hugh Angus (Head of Tree Collections) and Tony Aiello (Curator of the Morris Arboretum, Philadelphia), we saw the two species growing in close proximity (picture above) and I confessed I'd never looked into how they differed. Tony gave us a tutorial in the rather minor differences that separate them - a duller bark in C. mas, small distinctions in flower size and most telling, patches of hairs in the vein axils of the underside of the leaves in C. officinalis, visible even on last year's fallen leaves.


Cornus officinalis 'Kintoki' at The Patch
'Kintoki'
 As usually seen in cultivation, there is little to choose between the two species, but there is an exceptional clone of C. occidentalis in (limited) circulation, with really abundant, large clusters of flowers that really do make the others look rather pointless. This clone, 'Kintoki', was selected by Barry Yinger in a Japanese market and introduced by him to the United States (according to Cappiello & Shadow, Dogwoods, 2005). I've only ever seen one plant of it in the UK, growing in Margaret Owen's garden, The Patch, in Shropshire. It was noteworthy when a young plant several years ago, but now, as a young tree, it is spectacular, laden with flowers that even on a very dull day contributed a rich mass of colour to the garden. Cappiello & Shadow say its bark is 'as good or better than some Prunus species' so this may be another feature to look for as the tree ages, but it is not yet apparent on Margaret's specimen.

Cornus officinalis 'Kintoki' - the inflorescences have more flowers
than normal in the species.
Cornus chinensis is the third member of the trio. I have never seen it in flower, but it gains rave reviews from those more fortunate. Frank Kingdon Ward found it near Rima in southern Tibet in 1950, writing of the effect of the trees in full flower, a mass of yellow in the forest, and his puzzlement in working out what it was (Pilgrimage for Plants, 1960). It became his principal target for that collecting season, but his plans were rudely shattered by a massive earthquake, 8.6 on the Richter scale epicentred near Rima. After that the party had two priorities, survival amid the devastation and aftershocks, and to collect seed of Cornus chinensis. Both were successful, but this stock of C. chinensis proved to be tender in British gardens. More recently collected material from China is tougher and the species is now growing well in southern England at least. The foliage is outstandingly attractive,with a long drip-tip.

Cornus chinensis at Tregrehan







2 comments:

  1. This is a valuable tree and, as you say, esp. the variegated one.
    Must look for 'Kintoki' which sounds suspiciously like "Kentucky" in faux Japanese.

    The nursery staff were I work often graze on the fruits in fall along with those of Luma apiculata. The two together are quite tasty.

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  2. I am glad that Tony was over there demonstrating the well-versed horticultural knowledge found in the Philadelphia area. I have C. mas and C. officinalis in my garden, but now I feel I have nothing compared to the beautiful cultivar 'Kintoki'. I also am pretty taken by the foliage of C. chinensis.

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