Herts Flora Group field meetings

Ian Denholm

Our programme of field meetings for 2017 has now ended. My musings on 2017 meetings and botanical highlights are posted below. Field meetings in 2018 will be focused on areas in need of recording for BSBI’s Atlas project and/or checking on the current status of scarce species in the county. A full programme will be posted here early in the New Year.

Tring Park, 10th June 2017

Attendees met in the car park for Tring Natural History Museum, then headed south to enter Tring Park. A circular walk encompassed chalk turf, semi-natural and planted woodland, including a visit to Oddy Hill SSSI. Parts of the latter were somewhat overgrown but turf on the lower half of the slope had large numbers of Common Spotted-orchid (Dactylorhiza fuchsii), Common Twayblade (Neottia ovata) and Pyramidal Orchid (Anacamptis pyramidalis) together with other calcicoles. The real botanical prize was perhaps c. 10 plants of Yellow Bird’s-nest (Hypopitys monotropa), just emerging above ground and growing surprisingly in open turf rather than in the surrounding beech wood. This species has two quite distinct subspecies separated by floral characters that are not visible at this time of year. However, plants at this site have previously been assigned to ssp. hypophegea. Other than at Oddy Hill, woodland surrounding Tring Park contains a lot of planted and exotic trees and a sparse ground flora. Once back in the open we were treated to breathtakingly large colonies of D. fuchsii containing a range of colour of variants all in perfect flower. We got back to the car park just in time to placate museum staff who were waiting to close and lock up the carpark (it closes when the museum closes!).

HFG recorders at Tring Park, June 2017 (I. Denholm)

Yellow Bird’s-nest Hypopitys monotropa at Oddy Hill, June 2017 (I. Denholm)

Wheathampstead, 9th July 2017

The plan for this meeting was to progress from Nomansland Common to the eastern sections of Heartwood and end up in Sandridge village. However, the botanising proved so absorbing that we managed less than half of this itinerary! As one of the best remaining bits of heathland in Herts, Nomansland retains number of locally scarce plants, perhaps typified best by Lesser Gorse (Ulex minor), which is still frequent north of the road that crosses the site and appears to be spreading to new bits of the heath. It was a good chance to bone up on grasses favouring acid habitats, two of best indicators being Brown Bent (Agrostis vinealis) and Fine-leaved Sheep’s fescue (Festuca filiformis), which sounds as though it should be difficult but is really quite distinctive once you get your eye in. Alas, we were unable to locate Wavy Hair-grass (Deschampsia flexuosa) although I’m certain it must be lurking somewhere. Aliens are now a fairly constant feature of field meetings and two that generated interest were Virginia-creeper (Parthenocissus quinqufolia) spreading along a laneside (probably originally a garden throw-out) and the very attractive Cut-leaved Bramble (Rubus laciniatus) abundantly established on a patch of heavily-grazed heath, backing up Trevor’s statement in the Herts Flora about its preference for acid soils.

The part of Heartwood closest to Nomansland is dominated by a new arboretum, the brainchild of Brian Legg who chairs the Heartwood monitoring group. Brian’s ambition is to plant specimens of all the UK’s native trees (perhaps excluding some of the apomictic whitebeams) and he is rightly ensuring that the material included in the arboretum is of UK provenance. From a botanical point of view, the areas around the arboretum, like most open areas of Heartwood, have been seeded with mixes of different species so it is difficult to discern what is ‘natural’ from what is introduced. However, this area retained some species that are carry-overs from its former use for arable farming. Among these were Rye Brome (Bromus secalinus) and Great Brome (Anisantha diandra).

Fine-leaved Sheep’s-fescue, Festuca filiformis, at Nomansland, July 2017 (I. Denholm)

Cut-leaved Bramble, Rubus laciniatus, at Nomansland, July 2017 (I. Denholm)

Albury Nowers, 5th August 2017

The visit jointly with BNA to Albury Nowers produced the list of species expected for the site at that time of year. Given how extensively it has been recorded, it was unlikely that there would be notable botanical discoveries but I for one was very impressed with the sheer quantity of plants such as Common Valerian (Valeriana officinalis), Small Scabious (Scabiosa columbaria), Clustered Bellflower (Campanula glomerata) and Ploughman’s Spikenard (Inula conyzae). It is always a treat to be in the company of experts in other groups and I got to grips with at least three new fungi including the very fetching Polyporus leptocephalus. The only taxonomic uncertainty remaining after the meeting related to a whitebeam at the laneside between the railway station and the reserve. This keyed out to Swedish Whitebeam (Sorbus intermedia) despite the leaves being more deeply and sharply lobed than is usual.

HFG/BNA recorders at Albury Nowers, August 2017 (I. Denholm)

Ploughman’s Spikenard, Inula conyzae, at Albury Nowers, August 2017 (I. Denholm)

Royston, 10th September 2017

We were joined for this meeting by Alan Leslie, who is joint BSBI vice-county recorder for Cambridgeshire. Although the whole of Royston is administratively in Herts, and has been included in Herts floras written by Trevor James and John Dony, the boundary between Watsonian vice-counties 29 (Cambs) and 20 (Herts), runs through the town centre. It is possible to stand in the middle of Melbourn Street (quite busy so not advised) with one foot in each vice-county! While we expected the Royston visit to focus on alien plants, Alan pointed out two post-flowering colonies of Fine-leaved Sandwort (Minuartia hybrida) on side-street walls. This is a really rare native plant of disturbed and/or bare ground and walls and is probably to be found elsewhere in the town (including the vc 20 section). It is always worth looking at the pavement under hanging baskets for self-sown plants. One of the commonest generally, and frequent throughout Royston is the garden lobelia (Lobelia erinus). Also a couple of plants of the confusing horticultural genus Calibrachoa, seemingly not previously recorded as self-sown in the UK. Another group of aliens are those self-sown from gardens; we got Clematis montana and an evergreen spindle bush (Euonymous fortunei), new to VC29 and (I think) to the admin county of Herts. Galinsogas were frequent with G. parviflora unusually outnumbering G. quadriradiata. My experience elsewhere is Herts is that the latter is now by far the most frequent of the two,

Unfortunately a brief subsequent excursion to magical Church Hill on Therfield Heath failed to rediscover Autumn Lady’s-tresses, but compensation was provided by an abundance of Devil’s-bit Scabious (Succisa pratensis), plenty of Candytuft (Iberis amara) still in flower, and Autumn Gentian (Gentianella amarella) to name but a few.

‘Million Bells’ (Calibrachoa sp.) self-sown in Royston, Sept 2017 (I. Denholm)

Wild Candytuft, Iberis amara, on Church Hill, Royston, September 2017 (I. Denholm)

Hemel Hempstead, 8th October, 2017

Sometimes the most unassuming spots can be extremely rewarding botanically. This walk around the Frogmore End and Apsley areas of Hemel Hempstead produced a huge list of species associated with a range of disturbed habitats. Having parked adjacent to MacDonalds we crossed the road and encountered a patch of nettles by the River Bulbourne intermediate between Common Nettle (Urtica dioica ssp. dioica) and the Fen or Stingless Nettle (U. dioica ssp. galeopsifolia). These subspecies are clearly fully inter-fertile and highly introgressed, especially in damp habitats. One of the most exciting discoveries was the locally rare Rustyback Fern (Ceterach officinarum) in large numbers at two sites on walls adjacent to locks on the Grand Union Canal. Elsewhere on the canal sides we found self-sown plants of Western Red-cedar (Thuja plicata), Austrian Pine (Pinus nigra) and Italian Alder (Alnus cordata).

Apsley railway station is well worth a visit, even if you don’t want to catch a train. Beds alongside the approach roads had Narrow-leaved Ragwort (Senecio inaequidens), Perennial Rocket (Diplotaxis tenuifolia), Hoary Mustard (Hirschfeldia incana) and a host of others. Banks behind the railway platforms had huge quantities of Heath False-brome (Brachypodium pinnatum), which Trevor suspects to be spreading in Herts. It is easily overlooked given the hyper-abundance of B. sylvaticum; the initial jizz characters are upright rather than drooping panicle, shorter spikelets and much shorter awns. Residential roads nearby had pavement weeds that are spreading rapidly in the county including the increasingly misnamed Water Bent (Polypogon viridis), Shining Cranesbill (Geranium lucidum), and Mexican Fleabane (Erigeron karvinskianus).

Rustyback Fern, Ceterach officinarum by the GU Canal, Apsley, October 2017 (I. Denholm)

Water Bent, Polypogon viridis, in Hemel Hempstead, October 2017 (I. Denholm)