Wednesday, 12 April 2017

Fritillaria meleagris, Gagea rusts and the Muscari count

Following my post about Gagea lutea, I had a comment from Paul Chapman, the voluntary warden at Martins' Meadow in Suffolk, about the number of flowering to non-flowering plants.   Martins' Meadow has fritillaries, but the number of flowering plants has significantly declined but it looks as though the reason is different to the Gagea lutea situation.  The Suffolk problem seems to be a low water table, but at Whitehill Wood I could find no correlation between rainfall (a surrogate for water table) and flowering plant numbers, which have remained low but stable.

To look at a colony of Snake's-head Fritillary nearer to Hook Norton we went to North Meadow in Cricklade, and then on to Upper Waterhay and Clattinger Farm.  We saw thousands upon thousands of flowering plants.   At North Meadow the number of flowering to non-flowering plants was approximately 1:3 but we probably underestimated the number of juveniles.  (A very different ratio to that for Gagea lutea at Whitehill Wood)   It would suggest that from seed to flower is around  3 to 4 years - more if there is one or more years of  unseen bulb development underground.
North Meadow

North Meadow
From the literature, Fritillaria meleagris is widespread in Western and Central Europe, but despite the very large numbers where it does occur it is rated as a red data species or rare in Europe; habitat loss is the main issue.   Its origin in the UK is probably anthropogenic.

An obvious feature of the Cricklade populations is the number of purple to white plants.  The proportion  was consistent at each location but the figures for the three locations were very different.   At North Meadow we came up with a figure of 4.8% as the proportion of  white plants (total of 396 plants) whereas at Upper Waterhay the white proportion was 64.4% (194 plants).   At Clattinger Farm we found only 6 white plants across the whole meadow.  A quick look at the literature gave figures of virtually no white plants in 2 Polish populations, but between 3.5 and 5.8% for a Scandinavian population.   By contrast a definitely anthropogenic population in Poland was predominantly white.
Whilst white flowers reflect more UV no  difference has been seen in their attractiveness to pollinators.   During our visit we saw bumblebees and solitary bees visiting; the latter spent more time in the flowers, emerging covered in pollen, and very active in moving from one flower to the next.
Purple form


White form

I put spores from the two rusts found on Gagea lutea under the microscope.   The spores of Vankye ornithogali measured 16 x 12 microns, compared to 29 x 22 microns for Uromyces gageae.

Vankye ornithogali 

Vankye ornithogali spores

Uromyces gageae spores
Uromyces gageae



It was the Muscari neglectum count at Chadlington last Monday.   Unfortunately it was briefer than usual because most of the village green where there were hundreds last year had been cut probably three weeks or so ago.   It all looked very neat, but really!   (It's the same in Hook Norton; because most people cannot recognise even a handful of plants they see a grassy space and want it to look short and neat).  Worse, grass clippings had been stuffed into a shrubby area on top of Muscari plants.   There was some encouragement though in that areas we had cleared in the autumn  (gardening!) showed a recovery in the number of flowering plants.
An area cleared of denser vegetation in Autumn

Chadlington village green



Thursday, 6 April 2017

Orchid Twitching on the Dorset Coast

Slowly, very slowly, I have been digitising slides taken pre 2004 when I turned over to digital photos.   In the process I came across photos of the early spider orchid on the Dorset coast, and concluded that the coast walk and the orchids there were well worth a return.   We went Orchid Twitching  there yesterday on a warm sunny day, as is always the case in Dorset.


Starting at Winspit near Worth Matravers we walked round to Seacombe.  My wife was adept at finding the early spiders (a count of over 30 to my 3), but she stopped pointing them out after a while fearing that I would photograph each and every one.   Needless to say we never made Dancer's Ledge.  

The plants were only just coming into flower; on one only two flowers were open , yet the pollinia had already been removed from the lowest of them.

A wonderful day - one of the best orchids!







Tuesday, 4 April 2017

2017 Survey of Yellow Star-of-Bethlehem (Gagea lutea) in Whitehill Wood


Yellow Star-of-Bethlehem  is a super plant.   This year's count by the Wychwood Flora Group found 12 flowering plants with a total of 22 flowers, a little below average.   The number of flowering plants is quite variable year by year and I ran the count dataset which goes back to 1998  against climate statistics for Brize Norton which is the closest weather station that I could find.  I could see no meaningful correlations.

What was apparent is that there were very large numbers of non-flowering plants.  I selected at random a 5.5m long stretch of the path, counting plants on both sides to a distance of 0.4m on the river side, and 1m on the wooded bank side.   In total there was 1 flowering plant (with 3 flowers) against 63 non flowering plants at various stages of development.  Someone in the party thought that from seed to flowers takes 6 years, but the number of non-flowering plants is a ratio 10 times that which would be expected.  Why do so few plants flower?
Yellow Star-of-Bethlehem

Leaf tip - Yellow Star-of Bethlehem

Leaf tip - Bluebell for comparison

Non-flowering plants of Yellow Star-of-Bethlehem

Another of the party suggested we look out for two rust fungi that afflicts Yellow Star-of-Bethlehem.   I found both; a round one which I think is Uromyces gageae, and an oblong one, Vankya ornithogali.   Only the more mature plants were affected.
Rust fungus - Uromyces gageae
This year the toothwort was fully in flower and easily spotted.  Always a treat.

                  
Toothwort
                 

Toothwort

Wednesday, 1 March 2017

St David's Day Plant Hunt (NYDPH Revisted)

I am not Welsh - one-eighth by marriage only, so that does not count.   Nevertheless I celebrated St David's Day  by looking for plants in flower.   I followed for comparison the route I took on the plant hunt on New Year's Day: through the village, past the garden allotments, over 2 fields of pasture, an arable field, back down a lane and through another part of the village.  It is never very productive at the best of times but gives a representation of the flora of the village and the immediate countryside.  The views are pleasant.


Pasture

Arable


January and February have been cold and for example at the end of February I tried the moth trap on three evenings but caught nothing.  Today, with the temperature at around 10℃, was a little more Spring-like.  I found a very modest 17 plants in flower, the village being the most productive with weeds, naturalised plants and garden escapes.   The pasture had nothing unsurprisingly despite the presence of a marsh fed by a spring emerging from limestone further up.


Hazel

Hazel

Lesser Celandine


 Here is a comparison of the plants in flower on the 2 days.

01/03/2017 02/01/2017
Pineapple-weed Matricaria discoidea NYD
Ivy  Hedera helix NYD
Wood Avens Geum urbanum NYD
Shepherd's- Purse Capsella bursa-pastoris SDD  NYD 
Groundsel Senecio vulgaris SDD  NYD
Read Dead-nettle Lamium purpureum SDD  NYD
Dandelion Taraxcum agg. SDD  NYD
Hazel Corylus avellana SDD 
Common Chickweed Stellaria media SDD 
Annual Meadow Grass Poa annua SDD 
Hairy Bittercress Cardamine hirsuta SDD 
Daisy Bellis perennis SDD 
Snowdrop Galanthus nivalis SDD 
Common Field-speedwell Veronica persica SDD 
Ivy-leaved Speedwell Veronica hederifolia SDD 
Petty Spurge Euphorbia peplus SDD 
Lesser Celandine Ranunculus ficaria SDD 
Primrose Primula vulgaris SDD 
White Dead Nettle Lamium album SDD 
Greater Periwinkle Vinca major SDD 
Total 17 7

I saw my first bee of the year, a queen White-tailed Bumblebee.

I dallied a little looking at the hazel flowers - the female and male flowers are on the same bush but are separate.   Pollination is effected by the wind, so I looked to see if there was any difference in the distribution of female flowers - top to bottom - one might expect more at lower levels but  I could not see any. difference.
Hazel flower (female)
The next milestone is May 1 (May Day) so another chance to see progress of plants flowering.   Beyond that and I will probably have given up because grasses will be in flower and I find them far too challenging.




Sunday, 22 January 2017

Otter Signs

South of the village the streams flow east to the Cherwell and eventually the Thames and the North Sea.  They arise as springs west of the village from the surrounding limestone.   The village itself  stands on the upper lias, the Banbury ironstones.   A bright, frosty morning we went for a walk along the side of one stream and back along another.  There are several badger setts along the route, but several have been damaged by renewal of a power line a few months ago, where trees and understorey were cleared.  The setts are still there, but are now  fully exposed to the world.  

Badger territory


On every streamside I look for otter spraint; there have been otter sightings to the east in Grimsbury near Banbury and to the west 5 miles away on the Glyme just south of Chipping Norton, I found several sprainting sites last year.  Nothing though near the village, until today.

I rather suspected there might not be enough food near hook Norton for otters because the streams are quite modest, but there are several privately-owned fishing ponds around some of the rather more expensive properties.  Otters have spread rapidly in Oxfordshire since they were first seen in the county around 20 years ago.   In fact we were among the first to find spraints at that time - on the River Evenlode near to Daylesford - meeting suspicion and incredulity about the find.  Now otters seem to be near the village; I found one spraint on a rock mid stream not far from a fish pond.  There were also some partial prints in the stream bank, together with badger prints.  Almost certainly this was a casual visit (males will range as much as 20 km in a night, females a little less), probably helped by there being more water in the streams following heavy rain last week.

Otter spraint

I brought the spraint back to look at the food remains and my study now reeks of the it, that unmistakable sweet fishy smell.   So if anyone has never smelt the stuff....!  Had it been mink I would probably have had to move out, as they stink; they look similar to otter spraints but they are just bad.






Wednesday, 18 January 2017

Still Fixated by Knopper Galls

Yes, I haven't moved on (partly because there is not much else of note under the unrelenting grey skies, but then the galls continue to surprise).  In the last few days many more insects have emerged from the knopper galls that I collected from under a common oak (Quercus robur) in the third week of December, and subsequently kept in a closed container at a steady 20℃.  From the 14 galls of different shapes and sizes so far  there have been   6 of the alien host gall wasp Andricus quercuscalicis.    These are from the agamic, that is, non-sexual generation, and are therefore all female.

But far more numerous,- more than 60 - other insects have emerged.   All look very similar and I am reasonably certain that they are almost all parasitoid wasps with perhaps one or two of iniquiline wasps among them.  Parasitoids attack the host wasps that create the gall in the first place, whereas iniquiline wasps simply take up home in the gall - uninvited lodgers that can alter the shape of the developing gall.

It does make for a puzzle.   A paper from 1991 by Hails and Crawley (J. Animal Ecology 60 (2) 545 - 61) found little parasitism in the non-sexual generation i.e the galls on common oaks, unlike in France where there was much more activity by parasitoid wasps.  A more recent paper  however by  K Schonrogge et al ( Insect Conservation and Diversity, 5 (4). 298-311) lists 14 parasitoid wasps and 5 iniquiline wasps associated with knopper galls, all as far as I am aware UK natives.   Knoppers are a recent introduction so maybe over time native parasitoid wasps are adapting to the alien.

I counted 55 of the emerging wasps and grouped them on size and appearance.   My summary for which there are photos below was:

Type A 3.5 mm long    29  (metallic sheen)
Type B 2 mm long       22  (very similar to type A, but smaller)
Type C 2 mm long         2  (metallic green with bright yellow legs)
Type D  3.5 mm long     1  (all black)
Type E  2 mm long         1  (almost all black)

Attractive little beasts and as my wife tidily summed it up "lost to the world, no-one sees them".

Here is the gallery with some attempt at identification, or more precisely speculation.

Type A (maybe Mesapolobus amaenus or M. tibialis)

 










Type B (very similar to Type A, but smaller maybe a different sex (?), Mesapolobus amaenus or M. tibialis perhaps)

 









Type C (maybe Mesapolobus sericeus)












Type D ( maybe Eurytoma brunniventris)

 









Type E (perhaps the only iniquiline,  maybe Synergus sp.)