Normally when you go out with a load of botanists it’s a fairly sedate event; you don’t tend to need to walk very far from the car before you find something to stop and look at. And then the next thing is close to that, and so it continues. Over the course of a day you may walk a few miles but it’s normally at a very gentle, stop-start kind of pace.
So, when I was invited to have a look at some of the rarer plants at Wakehurst Place by Tom Ottley, the county bryophyte recorder, I got a bit of a surprise, and certainly more of a work-out than is usually the case. We went on 13 November, which was fairly dry, and only had a bit of rain near the end of the day. However, since it had been quite wet, it was very slippery, which added to the challenge.
Tom started intensively surveying Wakehurst last year, continuing the work that Howard Matcham started some years ago, and has been re-finding plants from older records as well as locating things for the first time. So, the day’s outing was less for us to search for stuff than for Tom to show us some rare and unusual plants. That meant that he knew exactly where to look, and we just had to keep up.
It all started rather gently. In one of the most-visited parts of the site there are hornworts. Indeed, two of the four British species of this little-known group must be passed by hundreds of people without their being noticed.
At first sight rather like liverworts, they have tall sporophytes which continue to grow throughout the plant’s life, and oily-looking, often dark green leaves.
Close by the sandy beds and banks on which the hornworts live was also one of the larger Jungermannia species. Still rather small, with leaves barely 1mm wide and very aromatic, Jungermannia hyalina also has distinctive perianths.
However, the major part of the visit was devoted to the sandrock specialists at the lower part of the site. Heading briskly down the track, Tom suddenly turned off and appeared to be going straight in to the bushes. It transpired that there was a small sandstone outcrop hidden from view, which hosted several of the key species. First, and most obviously, was the beautiful Bazzania trilobata – you can just see the three lobes on the ends of the leaves in the bottom left. Like many of the plants we saw, it is a hyper-oceanic species, typically found in the wet western fringes of Britain, so it is particularly unusual to find it in the south east.
This is also true of Scapania gracilis which also coated the rocks. Not quite as large as the Bazzania, it can grow to a few centimetres long and about 4mm wide, so is relatively large for a liverwort.
The same rocks were also home to Scapania nemorea, so we could easily compare the two species. This had very distinctive brown gemmae, and you can even see the toothed leaves on the plant in the middle.
Much further down, and in part of Wakehurst that is normally closed (and inaccessible) to visitors, is the main stretch of the rock outcrops housing the rare plants. Very shady and damp, it is one of the few places outside of Wales and Scotland where it is possible to find the tiny Blepharostoma trichophyllum, with each finger of the leaves being a single row of cells.
The rocks at the far end also provide shelter for the liverwort Harpanthus scutatus with its slightly bilobed leaves, which point forwards, and which has unlobed underleaves. It is another rarity in the south-east, as its distribution map makes clear (and it’s not that different from the distribution maps of many of these plants, though perhaps a little more extreme).
It didn’t take long for us to start getting quite muddy, as we started sliding down the hillside, and having to crawl underneath various fallen trees to access some of the more botanically-interesting parts of the rocks.
After all this focus on liverworts, finally Tom showed us a moss: Trichostomum tenuirostre, which again has a similar distribution as the other plants, and grows on damp acid rock. Other rocks had much larger cushions of it, and required lying on the mud to look at them. The pictures certainly make it look brighter than it was; the light levels were in fact pretty low.
In the same vicinity we also found the liverwort Jungermannia pumila with perianths, which Tom has also previously shown me in Forest Row, where it grows in a special spot near the river Kid.
There was also some Tunbridge filmy-fern about (Hymenophyllum tunbrigense), but that only distracted us for a few minutes before focusing on another tiny liverwort, common in the western uplands: Lophozia ventricosa, with its bilobed leaves and pale green gemmae.
Somewhat weary we plodded back up the hill towards the more well-known sandrock outcrops at Wakehurst. They aren’t as rich in plants as those at the far end of the estate, but did provide us with a chance to see the final tiny liverwort of the day: Cephalozia catenulata, with its yellow stems. And it’s not even in the field guide…
The next challenge will be to see if I can actually recognise any of these when I’m in the wet west….