A woodland wander in early December took me past the Comar Wood holly tree, which seemed to make a good topic for a Yuletide blog post – so here it is.
As far as I am aware, there is only one holly tree in our wood. It’s on a steep hillside amongst birch trees in one of the larger areas of remnant ancient woodland. On my recent walk I noticed that the holly tree had berries on it, which surprised me. Holly trees are generally either male or female and are therefore unable to self-fertilise (the technical term is ‘dioecious’). In order for a female tree to produce berries her flowers must be fertilised by pollen from the flowers of a male tree. The pollen is carried by insects, often bees. As I have not come across any other holly trees in the wood or surrounding areas I had assumed that our lone holly would not be able to reproduce – but I was wrong.
I do remember a while ago noticing a little holly seedling growing not far from the mature holly tree, so had been aware that holly was attempting to regenerate in the wood. However, this is the first time I have noticed berries on the tree. The berries mean that either this tree is able to self-fertilise, or that there is a local male holly that I have not found. I don’t know how far away a male tree could be for insects to carry the pollen to our tree. A bee book I was reading over the summer1 suggested that bumblebee foraging distances can be several kilometres, so perhaps the male tree could be some way away.
As for the self-fertilisation hypothesis – I am not sure whether wild hollies are ever able to self-fertilise. The Handbook of Scotland’s Trees2 says of holly that it is usually dioecious (does this imply it sometimes isn’t?). An internet search indicated that there are a couple of cultivated varieties that are self-fertilising, but didn’t come up with any results about whether wild trees could be. How our tree reproduced is a question I have still to find the answer to.
Holly is a great tree to have in the woodland so I am very pleased it has been able to make seed. Being evergreen with dense foliage, it provides nest sites and winter cover for birds and its berries give them winter food. Holly is shade-tolerant so can form a useful understorey component. In folklore holly is said to have protective powers, which is probably another good reason to have it growing in the wood!
Holly is a natural, though minor, component of oak-birch woodlands on acidic soils, like Comar Wood. I assume it would probably once have been more common here than it is now. As I was walking back down the hill from the holly tree I noticed the little holly seedling had been browsed off and had just two leaves left. I wonder whether grazing pressure in the woodland has, over time, reduced holly’s success in regenerating and caused its numbers to decline. Holly is palatable to browsing animals including deer. Its prickly lower leaves are a defence mechanism (they are less prickly higher up the tree where out of reach), but this does not always deter hungry animals. While the mature tree did not have any apparent browsing damage, the seedling must have presented itself as a tasty snack for a local deer. Our holly may need some help if it is to regenerate successfully. Some protection against browsing for any young hollies might help them get away.
At the moment the wood has no shortage of dense cover for birds because the spruce provides this. However, as we gradually remove the spruce it would be good to have other types of tree that can create this cover. Holly is one such tree, so I hope that it is able to regenerate within the woodland. As well as providing food and habitat for insects, birds and small mammals, its red berries and green leaves provide a splash of colour and some festive cheer in the winter woodland. Merry Christmas!