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.