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


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.