A parasitic plants update, the first of two (maybe three!) parts. This Part 1 isn’t about mistletoe (see Part 2 for that). Because now is the season for spotting other plant parasites – the ones that parasitise host roots not, as mistletoe does, host branches. It is also, of course, the season for spotting mistletoe seeds germinating – and that’s what Part 2 will be about.
For now though it is root parasites – starting with the toothworts, of which we have one native, Lathraea squamaria, a chlorophyll-free parasite of tree, usually hazel, roots. It appears above ground merely to flower, and is doing that right now, in March-April. It is fairly common across much of Britain but is often difficult to find, especially once the woodland herb layer (Ramsons, Bluebells, Yellow Archangel etc) has grown up and hides the flower stems. Sometimes you can find them by listening for bumble bee activity below the ramsons leaves, as the flowers are very attractive to bees when open.
This season we’ve hunted it down in a few Gloucestershire sites, quite a challenge at times (there is none, by the way, in our Devon and Cornwall haunts, as it is very rare in the extreme SW) . This specimen (above left), for example, pictured at the NT estate at Newark Park a few weeks ago, was almost invisible, completely covered in leaf litter, cleared for the photo. You can see from the young ramsons leaves nearby that, by now, it will probably be hidden by as they will now be higher than the toothwort.
Another example, this one home-grown, shows how easily they get hidden. This is in our Gloucestershire garden, a first shoot from seeds sown about four years ago, so very satisfying.
The first picture (left) shows it just emerging, on 12th March, with young Yellow Archangel shoots nearby (the garden variety Lamiastrum galeobdolon subsp. argentatum). The second picture (right) shows it yesterday, 25th April, now mature but dwarfed by the archangel growths.
There is a non-native toothwort too, the Purple toothwort Lathraea clandestina, which is long-lived and often naturalised near to (more specifically downstream of, as it likes damp areas) gardens where it has been grown.
We’ve been spotting this here and there for some years, in both the Gloucestershire area (e.g. there’s a good population downstream of NT’s Hidcote Manor Gardens – see picture left, taken a few years ago) and in Devon and Cornwall, where there are many sites along the river Tamar. We explored some new Tamar sites this season, not finding the massive growths sometimes seen, but finding some small growths in woods on the Cornwall bank upstream of Gunnislake. The picture (right) shows some of those, not as spectacular as those below Hidcote and almost hidden by the Wood Anemones.
The toothworts are holo-parasites – no photosynthesis of their own and relying on the host for all nutrition. The broomrapes, Orobanche species, are similar and will be flowering soon – maybe there’s a Part 3 to follow. But for now most of the other plant parasites visible are, like mistletoe, only hemiparasitic, with their own green leaves. Reliant on the host for some nutrition but capable of their own photosynthesis.
Of these the most obvious, from recent Devon explorations, is Lousewort, Pedicularis sylvatica, pictured here on Dartmoor last week. And looking a lot healthier than the similar picture I posted of the same species in a previous parasitic plant account back in 2020 (see https://diary.mistletoe.org.uk/a-back-garden-parasitic-plant-safari/).
In that account I also covered the young plants of Yellow Rattle, Rhinanthus minor, a hemi-parasite of grass roots. That is popular now in gardened wildflower meadows, helping keep grasses under control. You can now buy plant plugs of it, ready-growing, to plant into your lawn. The plugs, obviously, come complete with host grasses, otherwise the Yellow Rattle plantlets wouldn’t survive. The picture here shows a set of Yellow Rattle plugs recently delivered by NatureScape https://www.naturescape.co.uk/ and destined to soon transform a small lawn in Devon.
I also covered dodders in that previous account – more on those another time, maybe in Part 3. We do already have emergence of young dodder growth that has overwintered within a gorse stem (they don’t actually need to grow from seed each year) in Devon.
Mistletoe germination pictures coming soon….