Hooky Natural History: Orchid Hunt and the Irresistible Pasque Flower

There is so much to see and so little time.

Orchids when they first appear can be tricky to differentiate one species from another. Looking at Facebook postings most are just guesswork. A similar problem occurs when the plants have flowered but there are differences in the size and shape of seeds and the seedpods. Over the last few days I went to several locations with reliable orchid populations to see how useful the keys in Poland and Clement's vegetative key to British plants were, recognising that leaf width and length, a useful feature when plants are fully developed, was irrelevant. I am growing very familiar with keys JG to JL - whether stomata occured on upper as well as lower leaf surfaces, whether crenulate (toothy) or entire leaf edges, hooded leaf tip, and so on. I am also keen to see if there are other helpful characteristics that are not in the keys but which might be useful. With some species the keys worked, but others were more troublesome, where the keys did not reliably fit, and there may be other characteristics that could aid identification. I will have to return to confirm my tentative conclusions in 4 or 5 weeks time.

At Lea Valley, a calcareous fen valley near the centre of the city, and a famous botanical locality, I found leaves of Common spotted orchid (Dactylorhiza fuchsii) - leaves spotted, no stomata above, and a distinctive purple, crenulate (= minute round toothed) edge.

Lea Valley

Common Spotted Orchid Leaves

Common Spotted Orchid Leaf - Upper Surface and Edge

On Friday I went to Ardley Quarry, a BBOWT reserve around 15 miles from Hook Norton, finding Common spotted orchids again, but also what I think, and rather hope, were Southern marsh orchids (Dactylorhiza praetermissa) and a few Common twayblade (Neottia ovata) I will have to check these next month when they flower - a test for the accuracy of GPS. Southern and northern marsh orchids look quite different and as the common names suggest one is found in southern Britain, the other in the north. These are the BSBI distribution maps for the two species (all records). The overlap is very limited which begs the question as to why there is a clear geographical preference, one to the other. It is not explained by geology, could it be the amount of daylight?

Southern Marsh All Records Northern Marsh All Records

Recent observations suggest that Southern marsh orchid is pushing northwards with a few records from Cumbria since 2000. As an aside there are a scattering of records for D. praetermissa from the Skye and Raasay pre 1960; surely these are incorrect and might have been mistaken for hybrids of D. purpurella x D. maculata.

Ardley Quarry had other interest; 4 violet species which could be compared directly - Common and Early Dog-violet, Hairy Violet and a small patch of Sweet Violet, and some Stinking Hellebore (Helleborus foetidus).

Yesterday it was the BBOWT reserve at Westwell Gorse for Early purple orchids (Orchis mascula) and Common twayblade. Though both Early purple and Common spotted have variable, purple spotted leaves, the former are shinier and there is a clear leaf rosette, but not the purple crenulate leaf edge.

Leaves - Early Purple Orchid

Early Purple Orchid Leaf - Lower Surface and Edge

Westwell Gorse

Early Purple Orchid Leaf - Upper Surface and Tip

Some of the Early purple orchids were in bud, yet in some more southern locations there are reports of them already in flower. I had expected them to be in the shade and was slightly surprised therefore that at Westwell they are out in the open.

Westwell Gorse is not too far from Barnsley Warren, Gloucestershire Wildlife Trust's Pasque flower reserve, and the temptation to see the pant proved too much. Though I found less than 20 plants, in the shorter, rabbit grazed sward, avoiding the coarsest grassed areas, it was well worth the diversion. In my view the showier the better and very few can beat Pasque flowers; not for me the connoisseur 'delights' of grasses and sedges, bring on the showy flowers.

On a Celandine at Westwell Gorse, I found a fly which until I looked carefully. I would never imagined was a hoverfly. Glossy black, and in close-up looking like a boxer's sparring partner, helmeted and ready to go, I have it down as Cheilosia vernalis, though there are several closely related species and I might be wrong. Whilst it looks threatening and intimidating, bear in mind that it is only 5mm long.