Orchid Seeds and Seed Pods - A Diagnostic?

I have collected seed pod data for 33 orchids, measuring length and width, partly derived from photographs when they are in fruit and adding a scale to the photograph. There is variability; for some species, but not all, the pod size decreases up the inflorescence.  Nevertheless the ratio between length and width is more consistent for each species, and the number may be characteristic of that species.   I was able to use the ratio to discriminate between for instance common spotted orchid and chalk fragrant orchid.  The results overall show that the ratio can help discriminate between species, not necessarily conclusively but as an example Chalk fragrant orchid (Gymnadenia conopsea) and Pyramidal orchid (Anacamptis pyramidalis) which have similar leaf shapes have quite different values. I need to insert  note of caution though in that the sample size is small and often drawn from a single location.

I also collected small amounts of seed for 29 species, and measured length and width either under x40 or x100 magnification.   Generally I counted at least 10 seeds to give a reliable estimate, but in some cases only one or two.  The length; width ratio was not a good discriminator because long seeds were generally thinner and short seeds fatter, as if the volume was roughly the same (I need to look at this further).   The average seed length does though offer potential to discriminate, and again interestingly G, conopsea is a long way from A. pyramidalis.  

Also the genera are broadly grouped by seed length but this is accentuated when the seed length is plotted against the pod length : width ratio.   Clear clusters for different genera can be seen.

This chart seems to provide a way of discriminating between genera - dactylorhiza from gymnadenia say, and then the seed length and pod length : ratio might hint at species identification, but it is early days.  Too late this year to do any more work so a project for next year confined probably to those genera with several species such as the marsh and fragrant orchids and the helleborines, so that is the summer dealt with.    I also need to look at the literature - there is probably a whole lexicon on this and I need to compare and contrast, so that is winter dealt with also.

Orchids under the microscope

There was a time, when we lived on Skye, that I would be out and about in any weather.  Living down south I have got soft.  Because it was windy and wet at the weekend I spent time indoors dealing with the mass of photographs and information I gathered on orchids over the summer months.   I am interested in whether they can be reliably identified when not in flower, and I have concentrated on the edges and tips of leaves typically under x100 magnification, leaf venation, whether there are stomata before moving on to seeds (x100 magnification and seed pods.  The leaf characteristics I have compared to the descriptions in Poland and Clement (The Vegetative Guide to the British Flora), getting to grips with crenate and papillose margins.

I have summarised these in a PowerPoint files and there are some interesting differences.  For example P&C use habitat to differentiate between the three Fragrant orchids.   It works a lot of the time but not always; yet I think there are some subtle differences in the leaf characteristics - occasional stomata or not, edge characteristics and probably seed size (or more particulary the ratio of length to width).  This is an example of the presentation for one of the fragrants - chalk fragrant (Gymnadenia conopsea)

I collected data for around 30 species out of the total of 53 (?) in the UK and have so far summarised around a half.   Obviously I avoided the Schedule 8 plants and others that are rather rare and you would not stumble across them unless you were purposefully looking for them in a known location. One weakness though is that I have the very smallest of sample sizes for each but I am hoping next year to rig up something that can take at up to x60 magnification in the field.

Quite what I do with the work when completed, I am not yet sure!

Weeds

I have been looking for archaeophytes, the subject of the upcoming BSBI photographic competition.  Archaeophytes are non-native species, introduced in ancient times, considered to be around 1500.    For obvious reasons many are arable weeds.    The other plant classifications are natives, neophytes - plants introduced after 1500, and increasingly of garden origin - and casuals where a non-native plant, maybe a garden throw-out, hangs around for a year or two then disappears.

Back in the early spring the developer of the estate where I live, in order to eliminate any possibility of flooding from fields to the north, dug a 1.5 metre ditch which was then connected into the estate surface water drainage.  The bare earth has now been colonised by weeds, mostly, if not all archaeophytes, all of which must have been present for several years as seed, because the adjacent fields are laid to pasture.   I counted at least 33 species in the 80 metre length of the ditch, nothing rare as far as I am aware, but it will be interesting to see what happens over time.  The soil is heavy clay.

Ditch

Field Pansy

Spear-leaved Orache

Sun Spurge

Common Poppy

Bristly Oxtongue

On Sunday I ran the moth trap catching over 50 moths of 21 species.   My year to date total is now 146 species.  There were lots of November moths (maybe Pale November moths or Autumnal moths) but treated as an aggregate, because they are difficult to separate.   Moth identification relies in the main or looking for a match in one of the photographic or illustrated guides; for the amateur, unlike plants, there are no keys to work through.  Regularly therefore I have looked at pictures of a very handsome moth, Merveille du Jour (wonder of the day), wishing at some point I might see one.  On Sunday I had five; apparently they feed on ivy which is now in flower.  Sure enough it is one of the most striking moths.  November moths by contrast are just drab.

Merveille du Jour

November Moth