Tuesday, 29 April 2014

A quick trip to Upwood Meadows NNR

I'd arranged to pick Pete up from a meeting at Woodwalton Fen, and as we were so near to Upwood meadows we made a quick detour. I particularly wanted to photograph the heath dog-violets Viola canina subsp. canina, and we soon found plenty flowering in the north-west corner of Bentley Meadow. They are the last of the dog-violets to come into flower, and have a characteristic slate-blue colour, and a very blunt yellowish spur, as well as more oval lance-shaped leaves. They are classified as Near Threatened on the GB RedList, and are only found in heaths, acid grassland and fens.

And while I was there I couldn't resist a few photographs of the green-winged orchids Anacamptis morio which are flowering profusely. This is the harlequin of orchids, found flowering in meadows in late spring. Its Latin name, morio, means 'fool' and refers to the jester-like motley of its green and purple flowers. It gets its common name from the green or bronze coloured delicate green veining which lines the flower's hood. This gives it the appearance of having green wings. Unimproved grassland is the habitat most favoured by green-winged orchids and in Cambridgeshire it is restricted to a few ancient undisturbed hay meadows and pastures on the heavy boulder clay lands. 

The adder's-tongue Ophioglossum vulgatum was also proliferating, with several very large patches, holding hundreds, if not thousands, of fronds. And we found clustered stonewort Tolypella glomerata in the main pond. Not bad for a fifteen minute visit!

Sunday, 27 April 2014

Barholm and Greatford

Euphorbia helioscopia

Having suffered with a niggling back injury, I decided not to go too far yesterday, so drove out to Barholm, north-east of Stamford, and did a circular walk via Greatford. The first part of the walk was along a public footpath, first through an area of improved grassland and then a rape field. The latter had quite a few arable weeds coming into flower, including dove's-foot crane's-bill Geranium molle, field pansy Viola arvensis and sun spurge Euphorbia helioscopia.

The most interesting of the arable species was common fumitory Fumaria officinalis. I love the finely-dissected blue-grey smoky foliage that gives it its generic name, and the two-tone purplish flowers are exquisite.

Fumaria officinalis subsp. wirtgenii

Fumitories are tricky to identify and I always take a sample back to check. There are two distinct subspecies of Fumaria officinalis, and this one proved to be F.officinalis subsp. wirtgenii, which is the more frequent on light soils in eastern England, and worth looking out for in arable fields on the limestone or sandy soils. The racemes are normally 10-20 flowered, and the spathulate lower petal is truncate at the apex, rather than pointed. The fruits of this one were rather young, but they are about as long as wide (whereas subsp. officinalis has fruits which are wider than long) and often have a distinct apiculus. 

Truncate shape of lower petals of F. officinalis subsp. wirtgenii

Fruit shape, with apiculus

In Greatford there was a rather nice roadside ditch with a good range of aquatic species, while back in Barholm, stone walls proved to be quite rich, although also posed a dilemma. One wall, running between a farm and a garden had a number of species of Sedum as well as the house-leek Sempervivum arachnoideum. Had these established naturally (they were surrounded by moss and other native species such as Erophila verna) or had they been placed there deliberately?

Sempervivum arachnoideum

Sedum spathulifolium

Towards the end of the walk I came across a hedgerow weeping willow. Willows are notoriously difficult to identify, and early in the year the leaf characters are often unreliable. There are two taxa of weeping willow which you're likely to come across - Salix x sepulcralis and S. x pendulina. Fortunately this tree still had its female fruits, and the elongate, conical shape which are much longer than the subtending bracts make this one S. x pendulina.

Elongate fruits of S. x pendulina

Sunday, 20 April 2014

For the love of tiny things...

Many botanists are fascinated by showy flowers such as orchids - but what I really love are tiny flowers - and if they're blue that's even better. Now's the best time of year for these botanical miniatures, most of which are spring ephemerals growing in parched habitats. These annual species germinate in the autumn, flower in spring while there is still moisture in the soil, set seed and then shrivel to nothing under the heat of the summer sun.

This species is a particular favourite of mine. Early forget-me-not Myosotis ramosissima is a perfect miniature version of its more robust cousins, but its flowers rarely exceed 2mm across. We found sheets of it it in a disused sand pit in Lincolnshire, which is now a nature reserve.

We had been planning to visit Careby Wood, which is owned by the Forestry Authority, and shown on the most recent OS maps as Open Access land. But when you arrive at the supposed access point, there's no obvious track leading to the wood, and the only available path runs straight through the West Glen River, which was deep enough to require wellies to cross it.  We had to admit defeat, and despite further study of Google Earth I still have no idea how to get to it, as there are no public rights of way leading there. It seems very odd to have Open Access land which is inaccessible!!

Saturday, 12 April 2014

Neglected or overlooked?

Now's a good time of year to record two of the rarer or more easily overlooked chickweeds. Almost everyone will know Common Chickweed Stellaria media, probably because they have it growing in their garden. Greater Chickweed Stellaria neglecta is somewhat like common chickweed on steroids, and if you find a particularly large chickweed growing in a shady damp place, it's definitely worth a closer look. The key distinguishing characters are that the sepals of S. neglecta are usually larger than 5-6mm, the stamens are normally more than 8 in number and seeds are normally greater than 1.3mm in length. However, you do have to be careful, as S,media can grow large, particularly in fertile sites and may have from 3 to 8 stamens. I spent quite a lot of time looking at large Stellaria specimens last year and there were a few that were just on the boundary between the two species, where I eventually concluded that they were just S. media. If in doubt, take a reference specimen and press it. There's only been one post-2000 record of this species in VC53 (Bourne Woods, R. Jefferson) but I suspect it still probably lurks in some of the other ancient woods, hedgerows and shadier fens, so keep an eye out for it.

Stellaria neglecta 

Lesser Chickweed Stellaria pallida is almost certainly under-recorded. It is small, has a straggly, untidy appearance and is a pale yellowish-green. It's most likely to be found in inhospitable places, such as pavement edges, gravel roads and even mown grassland, where it flowers early in the year and then disappears. The sepals are generally smaller than those of S.media (less than 3mm), there are 1-3 stamens and petals are normally absent. The fruiting pedicels aren't reflexed at all, while those of S. media are curved downwards or flexuose. This species has been recorded from six sites since 2000, but five of those records have been made by me, probably because I see it regularly at a site that I monitor, and therefore notice it elsewhere.

Stellaria pallida showing characteristic growth form

Seed-head of Stellaria pallida

My last species is much more of a long-shot as it has declined significantly nationally and is now listed as Vulnerable in the UK RedList. Mousetail Myosurus minimus is a tiny annual member of the Ranunculuaceae that is characteristic of damp arable ground and cattle-poached areas (such as gateways and drinking troughs) in grazed pasture. However, it can turn up in other bare areas, and for a while there was a substantial colony alongside one of the Peterborough parkways, in an area that was regularly sprayed with herbicide. It hasn't been recorded in VC53 since 1920, but could still be about, as it's appearances are unpredictable and sporadic. The most likely places to find it would probably be cattle-grazed pasture round the Wash or along rivers and washlands, but it could turn up almost anywhere!

Myosurus minimus

Close-up of flowers

Sunday, 6 April 2014

Underwater reproduction

I thought some of you might be interested to see the miniscule (2-3mm) underwater flower of horned pondweed Zannichellia palustris, found yesterday while doing some botanical recording on the way back from Spalding. The 'flower' actually consists of four peltate stigmas, which are colourless and formed from a single layer of cells. In time these will produce the more obvious fruits that give this pondweed its name.

We also found a very extensive area of clustered stonewort Tolypella glomerata in a shallow ditch running south from the River Welland. This had many reproductive structures, which are the orange ovals in the tangled fertile whorls. This is a nationally scarce species of water with a high pH, ranging from semi-permanent puddles, through to ditches, pools and pits. Where sites dry up in the summer, but are flooded in winter, the plants germinate in autumn and overwinter, producing ripe oospores as early as May or June. 

Friday, 4 April 2014

Twitching Yellow Star-of-Bethlehem

Last Sunday I fulfilled one of those lifetime ambitions that only a geeky botanist would have - to see Yellow Star-of-Bethlehem (Gagea lutea) flowering. 

In the morning Pete and I had coffee with his Mum in Spalding, and then headed west to Morkery Wood, which I knew had two populations of this uncommon ancient woodland plant. After the first picnic of the year, and a short stop to photograph moschatel Adoxa moschatellina and wood sorrel Oxalis acetosella, we walked through the wood to find the southern population. After a short search I found two good patches, but alas no flowers. This is not at all unusual as this species is a shy-flowerer, and often persists in the vegetative state for many years. It can be tricky to find, especially when growing among bluebells, but each plant only has a singe linear leaf, which has either three or five noticeable ridges on the reverse.

Adoxa moschatellina

Oxalis acetosella

Although I was a little disappointed it was a beautiful day to be out, and there were plenty of other wildflowers to admire, including a solitary summer snowflake Leucojum aestivum (probably planted but first recorded in 2004), toothwort Lathraea clandestina, a good patch of small teasel Dipsacus pilosus and the hybrid between primrose and cowslip Primula x polyantha. We took a circuitous route and ended up walking near the northern boundary of the wood, where I knew the other population was located. 

Leucojum aestivum

Dipsacus pilosus seed-head

Primula x polyantha

I'd nearly given up hope when we found two extremely large patches of Gagea, both flowering profusely. Pete counted at least 118 flowering spikes, and most were in perfect condition. Bliss!

Gagea lutea