Sunday, 13 August 2017

It's Hawthorn Time

I've blogged previously on the abundance of Eastern Hawthorn (Crataegus x subsphaerica), but there are still very few dots in the BSBI database other than mine and those for Cambridgeshire, Cardiganshire and the London area.

Now (and until well into October) is a great time to go out and look. Look and ye shall find, probably very quickly. The sepals are rising! See my other posts (link to Crataegus in side bar) for typical forms. But if it has erect sepals it is probably (given its abundance) Eastern Hawthorn, or potentially its much rarer parent Saw-toothed Hawthorn (Crataegus rhipidophylla). There are other hybrids, but if in doubt over parentage there is usually a bush nearby showing a clear influence from Hawthorn (Crataegus monogyna).

Once your eye is in on leaf shapes and fruit characteristics, it is quite easy to spot suspect bushes. Particularly if showing hybrid vigour or if they have the large distinctively-shaped fruit.

Its more tricky with the form with reflexed sepals (nothovar. subsphaerica), particularly when closer to Hawthorn. But again large fruit, and the longer than wide sepals, will give the game away in many cases. I found a nice bush today, photo below

Both forms are widespread around Leeds as plantings, but are also widely naturalised and show the characteristics of a hybrid swarm, with all possible variants from one extreme to the other due to back-crossing. However, most are somewhere in the middle.

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