Ancient Woodland Indicator: Toothwort

Britain’s 2.4% of remaining ancient woodland is precious and under threat. It is rarely understood by developers that the whole ecosystem dates back centuries and is irreplaceable. Woodland plants can’t simply up sticks and move when their conditions become unfavourable or their tree cover disappears overnight. They can’t easily be transplanted into new secondary woodland. Ancient woodland conditions and species’ interdependencies cannot be recreated. The secrets of a plant species survival are often hidden underground. Science still doesn’t have all the answers or ability to replicate the conditions of the wild.

One of my year’s notable discoveries was Toothwort, Lathraea squamaria, in the Orobanchaceae family. It is an Ancient Woodland Indicator in the South West of England, and in other parts of the country too. I didn’t find it hidden in the depths of woodland. It was hiding under a Corylus avellana, Hazel tree in damp grassland, near a stone wall outside the wood. It suggests that ancient woodland extended to that area in the past. Toothwort can’t move back into the wood of its own accord. Its special growth characteristics mean that it couldn’t easily be transplanted back under woodland cover either. If its tree gets cut down, its chances of ongoing survival are remote.

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South West Habitat Changes

It is not unknown for woodland species to survive outside forests in the South West of England. Bluebells, Hyacinthoides non-scripta and Primroses, Primula vulgaris are regularly found in hedgerows here. However, I’ve noted that they are not found in the same abundance of my youth. Outside the woodland, they are more exposed to the unfavourable conditions of today’s intensive farming. If present, they tend to be on higher ground than in the past.

Tree Parasite

What’s so special about Toothwort, Lathraea squamaria? It is a heterotroph, unable to produce its own food. It is white, cream or whitish-pink, without the presence of food-producing chlorophyll. It lives as a parasite on tree roots. It has a preference for Hazel, Corylus avellana, but can also be found on Alder, Alnus glutinosa and Beech, Fagus sylvatica.

Dutch Elm Disease

Some older sources also mention Elm species as a host. Unfortunately, there aren’t as many Ulmus, Elm trees around today due to Dutch Elm Disease. I find it impossible to think of an Elm tree without simultaneously conjuring up the death knell of those terrible yellow crosses on their trunks.

Declining Species and Hosts

Although our native Toothwort is often described as Common Toothwort, according to Streeter it is rather a local species and in decline. Earlier observations perhaps explain why. Streeter also mentions Ash, Fraxinus excelsior, as a host tree in the Collins Wild Flower Guide (2009). Ash Dieback is threatening 95% of our Ash trees.

Botanical Recording of Toothwort

Toothwort, Lathraea squamaria, appears above ground in April and May. You can see the fresh green growth and catkins of the Hazel, Corylus avellana, its host (right). In any botanical recording, you will always need to identify the host tree. (I found the GPS OS Grid Reference app useful for recording, although I won’t share the Toothwort’s exact location here).

I’ve only mentioned one ancient woodland indicator in this blog. I hope that it nonetheless illustrates the high dependency of our native biodiversity on our trees and woodlands.

Web Links:

Francis Rose (1999): Indicators of Ancient Woodland: The use of vascular plants in evaluating ancient woods for nature conservation. British Wildlife, April 1999, pp.241-247. Online pdf last accessed 12 November 2019

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Karen does not seek or receive any commercial interest or advantage from this blog. She is not promoting any business venture. She simply loves to share fascinating facts about plants. These pages illustrate her love of plants, botany, biodiversity, gardens and creative expression. There is always so much to learn about plant diversity. This blog is designed as a showcase for photography, commentary on plants and wildlife, gardens and other places visited, horticulture and related topics. Viewpoints are her own, not those of her employer.

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