Monday, 26 June 2017

Post-flowering fate of Man Orchids at Ufton Fields.

Ufton Fields, a Warwickshire Wildlife Trust reserve, has a small population of Man Orchids (Orchis anthropophora).  In late May we counted 5 flowering spikes among the 25 cages marking plants that are, or have at one time been seen, there. In addition 2 more plants were in bud.  There were no plants outside the cages.  Excluding one of the 5, which was spindly and frail the average height of a flower spike was 26cm with 27 flowers on average.
Man Orchid in Fruit


Ufton Meadows - Man Orchid Cages

A frail plant that simply withered


I went back this morning to see the fate of these plants.  Without the cages they would have been impossible to find in the developed sward.   Lady's bedstraw and St John's-wort were everywhere.

The two plants that were in bud did not develop and had died off, as had the frail plant.   This left 4 spikes which had developed fruits with a total of 34 seed pods. Including the frail plant there were originally 123 flowers, so the fruiting success was 28%.  The fruiting success of individual plants varied from 0 (the frail plant) to 42%.

Last week we carried out a similar exercise at Bernwood Meadows, but not very successfully.   In early May we counted the flowers on 174 flowering spikes of Green-winged Orchids (Anacamptis morio) which averaged 6.8 flowers per spike in a survey area we created.   We went back to count fruits, at lunchtime on one of the hottest days of the year last week.   This is not an excuse for the fact that we could only find 31 of the original 174 flowering plants.  Those had an averages of 3 seed pods and 7.9 flowers.  The apparent fruiting success was therefore 38%.   But what of the plants that we could not find, which appear to be those with fewer flowers?  The total number of flowers we counted was 1193 and the total seed pods we found was 93; on this measure the fruiting success was only 8%.   The survey at Ufton Fields shows that unless individual plants can be identified in flower then again in fruit, assessment of the fruiting success is extremely difficult.
Bernwood Meadows
Fruiting Green-winged Orchid


Monday, 5 June 2017

Fruiting of Early Purple Orchids at Westwell Gorse

The Early purple orchids (Orchis mascula) are now in fruit at Westwell Gorse. 


In flower 4 May
In fruit 2 June

In flower 4 May
In fruit 2 June (top chewed)
In early May we measured the height and counted the number of flowers on 83 plants in a survey area we designated.  We went back on Friday to count the number of seed pods in order to estimate the fruiting success.  We found 63 plants; once the sward is higher it is  challenging to find just the fruiting plants.   For each we counted both the number of seed pods and the number of dead flowers that had not fruited.   From this we estimated the fruiting success at 36%, but it needs correcting.   In May the average number of flowers per plant was 9.8, whereas last Friday we got a lower figure of  8.6.   Either we missed some of the larger plants with more flowers, or more likely some of the buds that we originally counted as flowers did not develop, but just fell away.  If we apply an adjustment of 8.6/9.8 for the number of flowers then the fruiting success falls to 31%, which by coincidence is the same figure as in 2016.

The figure compares with references given for some German studies by Claessens and Kleynen in The Flower of the European Orchid ranging from 7 to 67% with an average of 34%.  Results from Sweden quoted in the same text were lower.   A Norfolk study (Hardy Orchid Society: April 2013) got a much higher result, 84%.  That looks atypical.

The range across individual plants was from zero to uncommonly 100%, with no real pattern.   The chart below plots Fruiting success (Y-axis) against Number of flowers per individual plant (X-axis)


It was noticeable that flowers at the top of the spike - those flowering later - were less likely to be pollinated, though we made no attempt to quantify the effect.

Pyramidal orchids were just coming in to flower, whilst there were 10 plants of Purple Milk Vetch, which is on the Red Data List.
Pyramidal Orchid

Purple Milk Vetch





Saturday, 6 May 2017

Early Purple Orchids at Westwell Gorse, and May Moths

On Thursday, w

e went to Westwell Gorse where there is a small patch of Early Purple Orchids (Orchis mascula).  I am keen to see what the fruit set efficiency of these orchids is.   We carried out an exercise last year and got a figure of 32% of flowers setting fruit, but the result was unreliable because of weaknesses in our survey technique - too large an area, too late in looking for fruits.


This year we restricted the survey area to roughly 4m x 6m, where we counted 83 plants, measuring height and the number of flowers.  Individual plants were not marked but the plan is to go back in 6 weeks or so, and count the number of pods on as many of this cohort as we can find.

                                                    

Naturally, larger plants have more flowers.   The average height of the flowering spike was 16.5cm, significantly less statistically  than the average last year of 20.3cm, probably because of the very dry period from late-March through April.   The number of flowers per spike averaged 9.8, higher than last year but significantly so.  Hopefully in addition to fruiting efficiency overall we might get some data on whether plants with more flowers have a higher percentage fruit set.

Incidentally we did not see any pollination activity, probably because it was dull, cool, and breezy.

My wife made an interesting observation.   Earlier in the week we were examining a nice population of greater butterfly orchids in the Chilterns.   There were very roughly 3 non flowering to each flowering plant (or to be exact, in bud).  With the early purples, there were few non-flowering plants, probably no more than 1:1, though small plants are difficult to spot in the sward.

Moth trapping at home has been a bit hit and miss.  Since the start of the year only a modest 16 species; on Thursday the catch was  moths, 3 species - a breezy, cool night.   But there was this rather grand Nut-tree Tussock.

                                             

Monday, 1 May 2017

May Day Plant Hunt

The same route, as on St David's Day and of course New Year's Day.   (In truth I jumped the gun by going a day early).

Trees in flower and grasses emerging boosted the count to 68 species.  Again nothing remarkable though oddly I could not find any bluebells, merely a small clump of the Spanish flower, Hyacinthoides hispanica.  Midland Hawthorn (Cratageus laevigata) which flowers earlier than its sibling, the usual Hawthorn (Cratageus monogyra) was far more widespread than I had expected.  I have assumed that the Cornsalad which lined one of the village roads was the common one (Valerianella locusta) rather than one of the other 4 species, and will check when the fruits emerge - unless the village warden tidies them away before then.

Midland Hawthorn Flowers

Midland Hawthorn Leaves

Ransoms

Goldilocks Buttercup
Medium-flowered Wintergreen

4 of the species were in flower in both the previous counts, and 14 of the 17 species in flower on March 1 appeared on the May Day list.  In total there have been 76 flowering plants on my route this year, not including the obvious overspill garden plants.   As ever the village was more productive than the agricultural land.

Oaks were beginning to flower but there were galls already on the flower buds.


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