Asian Dogwood (Cornus koenigii)

Its been just over 10 years now since Peter Sell first brought attention to the fact that that Dogwood (Cornus sanguinea), as understood by British botanists, included two non-native taxa i.e. Southern Dogwood (Cornus australis or sanguinea subsp. australis depending on preference) and Asian Dogwood (Cornus koenigii). Both of which were subsequently picked up from Stace 3 onwards.

Southern Dogwood is very widely planted, indeed many if not most 'native' plantings will be this and on this basis I think dogwood should be avoided in native planting mixes. Clearly growers are making no effort to distinguish native from non-native. As well as planted occurrences, it is also rapidly and aggressively spreading by seed from plantings. For example, it is increasingly being found in semi-natural habitats in Eastern England and West Yorkshire. In my opinion, it is still under-recorded in lowland England, and until more recorders split them (which is quite easy, only requiring a check of the hairs on the underside of the leaf) we won't truly understand how far it has established. Once known it can usually be told at a glance, although the hairs should always be checked.

In comparison, Asian Dogwood is much less commonly seen and of more patchy occurrence. I usually only see it planted into the wild and it seems less inclined to self-sow. So it was interesting to find a bush locally that is clearly of bird sown origin (there are mass-plantings within a few 100m as the berry-eating bird flies).

Asian Dogwood also has a very distinct jizz and can usually be told at a glance. As with Southern Dogwood it can form a large robust bush, but is generally less densely branched and in foliage, and the leaves have hairs like Dogwood. The leaves are typically large (much larger than Dogwood except where this is shade grown, and usually but not reliably larger than Southern Dogwood), clearly longer than wide (some forms of Southern Dogwood can have quite a rounded leaf outline in comparison), and have a markedly acute apex. The petioles are also very long relative to the other two species.

Invasion of the False Natives

Lookalikes (species similar to and planted in mistake for native species) and false natives (infraspecific taxa of foreign origin) have slowly been growing in profile over recent years following Peter Sell bringing these to a wider audience, and then the inclusion of a number of such plants in Edition 3 of Clive Stace's New Flora of the British Isles. But there is still some way to go in understanding the true distribution of these taxa, and the long term implications of 30 years zealous tree and shrub planting as quick fix habitat mitigation and creation.

Southern Dogwood (Cornus australis or Cornus sanguinea subsp. australis) is one good case in point, with the following map showing a rash of dots across central England. This species is almost ubiquitous in recent plantings in VC31, and is increasingly being found bird sown. A similar picture is building in VC64. My personal view is that this isn't a trivial matter. Southern Dogwood seems to grow more vigorously and forms a much denser bush, so I can see it being a problem for habitat managers in the future. It is obvious why horticulturists have favoured it as it has larger flowers and leaves than the native plant, produces a neater denser bush and has brilliant autumn colour.



The characters used in keys to distinguish it from Dogwood (Cornus sanguinea) are subtle and based on the number of leaf veins and the morphology of leaf hairs, but this belies the genuine differences between the two species. The leaf hair differences, visible with a hand lens, are well illustrated on the Manual of the Alien Plants of Belgium website. Once known the two species can usually be told at a glance with very high accuracy, but it always advisable to check the hairs. More recorders need to be looking for and distinguishing the two species if we are to have a representative picture of their true range in time for the next Atlas.

The typical large and rounded foliage of Southern Dogwood

The hybrid hawthorn Crataegus x subsphaerica is the subject of a separate post which can be found here. But I just wanted to show the current map of is distribution in VC63 and 64 following targeted searches this autumn. Note the two new locations well to the north of the Leeds cluster. It will be interesting to see how many new dots are added in 2017, I suspect it is going to prove very widespread and abundant.

What is interesting about my find at Moor Monkton (VC64) is that the original planted trees appear to have produced new trees much closer to Hawthorn (Crataegus monogyna) than the original stock. This suggests backcrossing, and this will add to identification difficulties in the future. Similar backcrossed bushes were found bird sown at Knostrop where there is a hedgerow dominated by the hybrid and estimated to be 30 years old. Clearly the hybrid has been with us for a while and has had plenty of time for birds to spread it around, so hybrids could potentially turn up anywhere.