A “Clandestine” plant ?

Take a look at this picture…you see a clump of  conifers (precisely Chamaecyparis pisifera, Japanese cypress) with nothing special ? Correct.

Now look down at the ground, under the trees. Hmm, a purple cluster of flowers, and a pungent smell. What on earth is that?

It’s called Lathraea clandestina. Despite its striking colour, it is usually well hidden under trees, hence the attribute “clandestine“. It’s native from Belgium, France, Northern Spain & Italy but has been introduced in the UK as a garden plant.
What’s so special about this plant? It’s one of the true parasites : Lathraea has to suck nutrients from its hosts (usually willow or alder, but not always!) because it lacks chlorophyll and can’t photosynthesize. Its underground stem bears yellow scale-like leaves resembling little teeth, hence the common name Toothwort.
Don’t you find it really pretty? 😉

I’ve spotted this one in le Jardin Massart (my ex-university garden), a very nice park unknown to many (maybe because it’s closed on week-ends 😦 ) but home to several rare plant and animal species. It encompasses a natural wetland, an arboretum, an orchard, and several themed gardens (honey plants, plant systematics, medicinal plants..). Ready for a little visit?

I was surprised to see Fritillaria meleagris (Snake’s Head Fritillary) delicate flowers (it’s considered extinct in Belgium, so these are most likely introduced) and Chrysosplenium oppositifolium (Opposite-leaved Golden Saxifrage) with its peculiar yellow-green flower heads.

Another sweet encounter : Leucojum aestivum (Summer Snowflake), taller than the  Spring Snowflake (Leucojum vernum). Not an usual sighting in Brussels : Corydalis solida (a kind of Fumewort), with its characteristic tube-shaped flowers.

In the marshy zone, it’s the perfect time to see Caltha palustris (Kingcup)  flowers (notice how close it looks to the Lesser Celandine, also flowering at the moment…it belongs to the same family, Ranunculaceae). I was also surprised to discover wild Hippuris vulgaris (Common Mare’s Tail). I have a few planted in my garden pond, but this native plant is considered critically endangered in Wallonia.

Damp soils are also favoured by the Cuckoo Flower (Cardamine pratensis), which is edible, and the Great Horsetail (Equisetum telmateia), a primitive plant reproducing by spores instead of seeds. What you see here is a strobilus, a bizarre non-photosynthetic cone-like structure bearing the spores.

With some many flowers blooming, insects have a lot of pollination work to do! Check out this bee fly (Bombyliidae), a hairy fly resembling…a bee. Bombyliidae bear a long proboscis, which helps them to feed on the nectar of tubular flowers.
I also met metallic blue beetles which were mating everywhere (Chrysomelidae, leaf beetles). Quite a showy colour, probably a case of aposematism (insects “warn” their predators that they are toxic by displaying bright colours).


  1. Nice post. I’m hoping to write about plant parasites soon too! I’ve never seen a Corydalis solida before – the flower is lovely!

      1. No problem! I’ve just come back from a day in Bruges – what a lovely place (very cold yesterday though!). I may be asking for your advice on a couple of plants if I can’t ID them in the next few days 🙂

  2. I’m really glad that I read this post because we saw a Lathraea clandestina at RHS Wisley yesterday and without your post I would have struggled with an ID! It’s interesting to see the similarities of plants that are in flower now in England and Belgium 🙂

    1. I’m so happy my post spared you some ID work, helping people is a big part of my goal 😉
      Lathraea clandestina is apparently spreading well in the UK, but still, it’s not easy to spot. Congrats!

      1. Lucy spotted it first and from remembering your photos I knew immediately what it was. We saw it growing in 2 places at the RHS garden, which I was quite surprised at. But I guess they’ll know how to keep it from taking too much from the plants it parasitises on. As a side, the English common name for this is Purple Toothwort – is that similar to the common name where you are?

      2. Actually we have no common name for Lathraea (as for many plants). French are really uninspired when it comes to naming plants or animals! I’m trying to learn the English names, but there are so many of them, and they can be tricky (for example, lesser and greater Celandine which are not related at all !)

        From what I have read, Lathraea is not like Mistletoe. Although it’s a true parasite, it does not seem to take too much energy from its hosts.

      3. This is my first year of really trying to ID things, so I know what you mean about there being so many English names. Especially when there are different common names in different regions of the UK. What’s spurring you on to learn the English names?
        If I understand correctly, Mistletoe is semi-parasitic due to its ability to photosynthesise?

      4. I’m moving to the UK quite soon, and I don’t want to be too lost (especially if I find a job or volunteer position related to nature). 😉
        Wow, you’re doing a good job in ID-ing if you only started this year!

        Mistletoe is indeed a hemi-parasite, so it only takes water and minerals from its hosts and gets its sugars by photosynthesizing. Holoparasites like toothwort have to take everything, water, nutrients, sugars….If you’re interested in that topic, check the wesbite of Dan Nickrent, he’s a very passionate researcher! (http://www.parasiticplants.siu.edu/)

      5. Ah ok. I did wonder why you had joined WAB. Are there more opportunuties over here for you? To be fair you and my other WAB friends have been great at helping me when I’ve gotten stuck with an ID or needed an ID confirming. I’d not have come along anywhere near as far without WAB.
        Thanks for the link. Now that I had a hemi and a holoparasite I’ll get ready to write a post about parasitism. Although, it would have been quite nice to add Yellow Rattle (Rhinanthus minor) – I think it’s a few months off flowering, so will probably leave it out!
        Looking forward to your next post…!

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