Identifying Dactylorhizas of Malham Tarn, Yorkshire

Across Malham Tarn towards the raised bog.

On 24th June 2025, I joined forces with 'The Upper Wharfedale Field Society' on a botany field excursion to Malham Tarn board walk trail and Sinks around the Tarn. Unfortunately the weather wasn't so good, it was dark and overcast with rain was forecast throughout the day. Nevertheless, with great fortune, as we put on our waterproofs, the heavy rain eased and we were able to venture to the boardwalk to enjoy the beauty of the place. I wasn't leading the group, but as we entered, by the gateway, I introduced the group to the first interesting find of the day! Not an orchid, but the Nettle-Leaved Bellflower (Campanula trachelium). It is relatively similar to the Giant Bellflower (Campanula latifolia) however, it is easily distinguishable due to its overtly nettle-like leaves and particular hairy stems. I guess thats a great reason to be part of a group - each of us have a different knowledge of plants and collectively can quickly achieve a wide picture of the plants associated to each habitat that we encounter. Even though I specialise in orchids I have come to know a wide range of plants by always being keen to learn anything new and having an open-minded. By the way I highly recommend the Upper Wharfedale Field Society.

The stunning Malham marshes

The boardwalk trail at Malham threw many great botanical surprises and orchid ones too! The trail takes you through several different types of habitat: alkaline flushed marshland, deciduous woodland and an acid raised bog. It is an upland marvel of a place. I love it. In fact I love it so much I headed back to explore it two more times over the course of two weeks. Quite frankly if I hadn't other duties this week, I would be heading up there again – maybe next week?

Through the woodland on the boardwalk

So, back to orchids. Interestingly The National Trust, who own the Malham Tarn Estate, keep open a little information area in the old Orchid House, of the Estate. Yes, the estate itself used to have an Orchid House! At the back of Malham Tarn House, inset part into the hillside and wall is the Orchid house. A room - noted by a new glass design to its door and windows – that of a Lady's-Slipper Orchid – nice!

The window of the Orchid House

Malham Tarn once had its own, rare Lady's–Slipper, which grew very close by in the old rockery at the side of the house. It, like all the other Lady's-Slippers, that were known, around the turn of the last century, was eventually stolen. Today, between the rockery and the main track, for some unknown reason, probably in homage, in a steel cage, grow more Lady's-Slippers – they seem to grow rather well there too!

The cage of Lady's-Slipper Orchids

[If you want to know more on this caged orchid I detail it in my book – The Dales Slipper]

In the Malham Tarn orchid room, mounted on the walls are information boards. Many depict wildlife that can be found in the Malham Tarn area. On one board is a photograph of a Dactylorhiza labelled as a Common Spotted Orchid (Dactylorhiza fuchsii).

The Dactylorhiza shown is most likely the hybrid between Northern Marsh and Common Spotted orchid called Dactylorhiza x venusta. It is almost comparable to the one I photographed, shown further below.

The fact the National Trust got it wrong is nevertheless quite interesting, because, I found the myriad of orchids and their hybrids I came across a sod to identify in the field, being rainy most of the time didn't help either. Thank goodness for photographs, without them I couldn't have managed to get any where near rightful determination! Now here's my disclaimer! If you believe I have wrongly named any of the orchids shown here, please let me know. I might sulk a little knowing I got it wrong, but hey I will get over it, and certainly learn from it.

There is one important rule of identifying plants that any orchidologists should learn - that is the process of deduction! Once you have determined the main parent/species within a site you can slowly determine whether the plant you are looking at is a sub species, variety or an interspecific or intergeneric hybrid. The process is often more trickier than it sounds, especially when you come across a hybrid swarm. Southern Marsh orchids (Dactylorhiza praetermissa), for example are notoriously mind numbing, they seem to mix with just about every other Dactylorhiza they come across. Local knowledge as well as getting to know distribution maps, such as that https://plantatlas2020.org/ can often help in that deduction process.