Helleborines (Epipactis) in Fruit

Over the last few days I made a couple of trips to the Chilterns and one to a wood near Solihull to look for helleborines in fruit.  I found four species, dune, broad-leaved, green-flowered and violet.

I measured the fruit set success by counting the number of seed pods compared to the number of bracts in the inflorescence.  

	Fruit set	Fruit set
		Sample size
Dune	89%	9
Broad-leaved	89%	3
Violet	37%	1
Green-flowered	72%	2

Both dune and especially green-flowered, are self-fertilising.   Green flowered did not open out at flowering time, but nevertheless set fruit.  High rates of fruit set are therefore to be expected.  With green-flowered some of the flowers simply blackened and withered.

The fruit set % for violet helleborine is again to be expected; it is pollinated by bees and wasps, but it grows in deep shade, where wasps are not commonplace.  Higher fruit set rates are commonplace in mainland Europe though.   By contrast broad-leaved helleborine seems to attract every wasp from a distance around and that leads to a high fruit set.

Tree Wasp Pollinating Broad-leaved Helleborine in early August

These though were not random samples - I was attracted to the biggest and boldest in the case of broad-leaved helleborines, and later I did find a few plants where spikes had no seed pods.

Dune Helleborine

Green-flowered Helleborine

Broad-leaved Helleborine

Violet Helleborine

I then took averages of the seed pod width and length for each species and the angle that the seed pods are held from the vertical (facing up then less than 90°, facing down greater than 90°.   I finally brought a few seeds of each home and got an average for length and width.

	Seed pod		Angle	Ratio	Seed		Pod L;W ratio
	L mm	W mm	to Stem °	L:W	L mm	W mm	over Seed L
Dune	10.3	6.8	94	1.41	1.11	0.24	1.26
Broad-leaved	12.4	7.6	126	1.63	1.08	0.26	1.51
Violet	11.3	6.8	118	1.67	1.29	0.20	1.28
Green-flowered	10.2	6.7	157	1.54	1.06	0.19	1.46

The angle held to the stem is interesting, and is helpful in discriminating, as too is that final calculation - the pod length:width ratio divided by seed length.   This together with the angle to the stem, and leaf colour and dimensions should enable a helleborine to be identified to species level.  Of course though my sample size was far from statistically sound.

For the broad-leaved helleborines I also  worked out pod dimensions by the position on the inflorescence.

	Average	Average	Average	L:W
	Angle	Length mm	Width mm
Bottom Quartile	137	14.1	8.1	1.73
Lower Middle Quartile	123	13.0	7.7	1.69
Upper Middle Quartile	134	12.2	7.7	1.58
Top Quartile	113	10.6	6.9	1.55

The seed pods became smaller and less narrow moving up the stem, and were kept nearer to 90°.   I did not have enough measurements from the other three species but violet did not seem to behave in the same way.

I then ran out of things to measure! 

Orchids in Fruit at Yeosden Bank

Yesterday we joined the ANHSO field trip to Yeosden Bank in Buckinghamshire near Chinnor, one of the newer BBOWT reserves.    It was led by BBOWT's warden.  It is an area of chalk grassland with a small area of woodland - ash and beech.   In the grassland were lots of  Chiltern gentians (Gentianella germanica)  and Small scabious (Scabiosa columbaria).   At the woodland edge there were dense patches of Devil's-bit scabious (Succisa pratensis).   To some the latter is quite a novelty, but from my time on Skye I remember it as one of the commonest plants, found in almost every tetrad on the island. Whereas to me, Chiltern gentian is worth getting excited about!

Chiltern Gentian

Small Scabious

Devil's-bit Scabious

Yeosden Bank has several orchids and I thought I would try to identify spikes based on appearance, leaves if extant, seed pod dimensions and the angle of attachment of seed pods to the stem.   I think I found examples of three orchids, Common spotted, (Dactylorhiza fuchsii), Pyramidal  (Anacamptis pyramidalis) and Chalk fragrant (Gymnadenia conopsea):

Probably common spotted:

Seed pod length 9.5 mm width 4.2 mm
Angle of attachment 29 degrees

Probably common spotted:

Seed pod length 7.7 mm width 2.7 mm
Angle of attachment 37 degrees

Probably chalk fragrant:

Seed pod length 7.4 mm width 2.6 mm
Angle of attachment 11 degrees

It is getting a bit late in the year for butterflies, but were numerous butterflies still to be seen though many were worn.  Amongst the fairly battered Common Blues, I am pretty sure this is a fairly battered Adonis Blue. 

A mammal stole the show however  - a hare running up the bank.   As ever only a fleeting glance - and much too fast for a  photo opportunity.  They are such a treat to see.

Autumn Lady's-tresses close to home

North Oxfordshire, sitting on ironstone and clay, is not rich in orchids.  The nearest reliable sites from Hook Norton are more than 15 miles away.

Well that has all changed - ok, just a bit.  Last year the joint vice county recorders for Northamptonshire, found a single plant (?) of Autumn Lady's-tresses in Banbury (it's in the administrative county of Oxfordshire but the botanical vice-county of Northamptonshire, so they weren't trespassing).   A  mere 11 miles from Hooky, I went to the site yesterday to see for myself.  Its on an industrial estate to the east of the town centre which was part of the expansion of Banbury alongside the M40. 

There were 6 flowering spikes in all, though one was damaged, on a landscaped road verge, which fortunately had not been mowed for two or three weeks.   Only in the one place though possibly because other verges are kept mown rather more regularly.   My priority now is to try to convince the owners and maintenance contractors to restrict mowing until after tha plants have fruited.