Gymnadenia spp… Fragrant Orchids
This study relates to a small but remarkable occurrence of the beautiful Fragrant Orchid on the shore of Lough Gara, Co. Sligo. There are many specimens there, large multi-flowered plants in various shades of white, pink and purple, consistent in form but variable in height. They are beautiful and sweetly aromatic and confined to a small paddock of 0.25Ha. Why study their classification? This group is largely of identical phenotype with a few variations on the widely accepted classification. The Taxon is now considered to contain 3 species, G. densiflora, G. conopsea and G. borealis. Most of the specimens recorded seem to conform to the species G. densiflora containing many tall spikes up to 70 cm. and over 100 flowers and with labellum and sepal characteristic of the species.Taxa Records, Images and Observations…
(Trio) No. 2, July 27th 2018
TAXA: The word comes from Taxonomy, the science of natural classification. A Taxon is a group of plants (for example) that may belong to a particular genus, that may be subspecies, that may be genetically the same but have acquired distinct identities as species or varieties or some other rank. The subspecies rank is particularly difficult; using the term ‘taxa’ (in the plural form) we can conveniently list species that are related in some ways but avoid some of the debates as to how!
The Site:
The site we are studying is on the north shore of Lough Gara in Co. Sligo. It consists of a series of small rectangular fields bordering the lake. Behind these are larger fields which are actively farmed. Of these small fields one has few orchids, another has a good population of common Dactylorhiza orchids and many interesting specimens that would appear to be Dactylorhiza/Gymnadenia hybrid. The third field — the one we are studying — is furthest west and has a large population of Gymnadenia, Dactylorhiza and hybrids. The evident first observation on this population is that it is large. We have never seen such a large population of Fragrant orchids and it is an impressive site. The second striking feature of this population is the large size (up to 70cm) of some of the orchids. There is a striking variety between tall plants and small plants — probably, we suspect, due to growing conditions and plant maturity. The height alone and the habitat would strongly point to these specimens being Gymnadenia densiflora. Other morphological characteristics of the flower in all Gymnadenia specimens observed would be fairly consistent and compliant with sp. densiflora classification.The Group (taxon)
Fragrant orchids used to be regarded as one species, then as subspecies (e.g. G. conopsea densiflora) and now as three separate species. It is a varied and confusing taxon with several very variable diagnostic guidelines given, including a difference in smell between the three species. One species, Gymnadenia conopsea (the Chalk Fragrant Orchid) is less common in Ireland but we have experience of it from chalk uplands in England. KEY: The characteristics and habits of this group that we have developed, or appreciated, in identifying them are listed below. (The letters refer to particular sources.): Flowering: June June/July July August a) borealis (Aug) conopsea densiflora b) conopsea densiflora Habitat: Dry/Chalk Heath Base Marsh/Fens a) conopsea borealis densiflora c) conopsea borealis densiflora d) conopsea densiflora Height: < 30cm 30 - 50cm 50 - 90cm a) borealis conopsea densiflora b) conopsea densiflora d) borealis conopsea densiflora Smell Sweet Sweet/Rancid Clove/Carnation. d) bor/con/dens a) conopsea borealis/densiflora c) conopsea borealis b) conopsea densiflora Labellum: width > length width = length length > width c) densiflora conopsea borealis b) conop & densi a) Sepals: hanging down up short shaped parallel long c) conopsea borealis densiflora d) conopsea/borealis densiflora b) conopsea densiflora a) conopsea borealis densiflora Spur: <12mm 12 - 14mm 15 - 20 d) borealis conopsea densiflora b) densiflora conopsea (+ curved)
borealis
conopsea
densiflora
Interpretation:
The simplified Table outlined above is very much based on our own observations and reading the literature and rooting out some more specialised opinions available online. The table format is our own devising made in an attempt to come to grips with a confusing array of opinions and observations. Last year we were very much of the opinion that two species were present along with many hybrids. This year we have not been able to clearly identify any species other than G. densiflora albeit present in a variety of morphs and sizes. The little icons reproduced above (after Cronodon) are one of the most useful guides we have come across. The fragrance issue we have found hard to interpret; either we have weak noses or all the non-hybrid flowers are identical. However, in among all the authors there is one solid book which simply describes all species as… ‘sweetly scented’. (Stace, New Flora of the British Isles, 3rd Edition). Other characteristics, such as habitat, size, flowering time are much more meaningful with the vast majority of specimens in this cluster coming into full bloom in the 2nd half of July. This, and the size, number of florets per spike, and the sturdiness of the often keeled lower leaves points to densiflora as the species representing the taxon at this site.Hybrids:
As mentioned at the start of this page, we are studying 3 adjacent lakeshore fields. These are really more like strips of land separating managed farmland from the shoreline. They are of similar size but gradually changing habitat. The furthest west has the greater area of usable habitat and is less ‘improved’. i.e. the effects of fertilisation (a possible cause of loss of orchids) of the upper fields seems to be less significant here than in the first two fields. The grass is weaker here and the orchids are stronger! Fragrant Orchids are absent or very reduced in the first two fields whereas they are numerous and spectacular in the last field. This looks like a programme of attrition whereby an established population is being marginalised by developing more intensive agriculture.
LEFT:
A typical ‘Dactylorhiza type’ orchid found growing in among the Fragrant
Orchids. A sturdy plant with spotted leaves and strong tightly clustered
flowers with large sides to the lip and smaller pointed centre lobe. The
strong streaked patterns are characteristic of a Dactylorhiza.
RIGHT
Many white flowered orchids are also present in the Study Field. One of these is a pure
white Gymnadenia (shown below). It was the only white Fragrant orchid found in this
area and it only flowered in 2017. (But see images from The Burren at the end of this
report.) The other white flowers are common and recognisable on close observation by
the typical dactylorhiza streaks and pattern on the upper labellum. They share
characteristics of both Dactylorhiza and Gymnadenia. They are, we believe, hybrids.
These two species are well known hybrids and numerous variants in terms
of background colour and striping can be found in this small area. However,
they all have some form of striping to indicate their Gymnadenia X
Dactylorhiza parentage.
NOTE: The stunning white orchid shown below, however, has no signs of
‘dactylorhiza’ influence and we believe this to be a true albino version of G.
densiflora. This was truly spectacular plant, tall and perfect and beautiful. It
survived all last Summer but has not re-emerged in 2018!
Colours and Variation:
Within this population (of G. densiflora) there is both a consistency and a variability of colour. In nearly all visits to this site we have encountered changeable weather. Rain and cloud optically produce rich colours; sunshine tends to create an unreal glare. We have taken photographs in all these conditions and have managed these photographs to truly reproduce the colour of the plants on the ‘average monitor’. In particular it is the Purple/Magenta balance that is prone to rapid variation. Purple is a very familiar colour; Magenta is a more technical colour akin to dark pink? Many of the taller specimens of G. densiflora will have magenta tips to the flowers (almost red) and progressively become more purple towards the bottom — fading almost to pale mauve as the flower matures. The population being studied here had this year (2018) very little natural range of colours and any variability seems to be a factor of their health and viability. Small plants had very yellow stems and large vigourous plants had lush green foliage at least up the the base of the flower. Colour is like smell, a very personal interpretation which may be a result of only minute changes in the pigments of maturing flowers or the lighting at the time of photography under rapidly changing weather conditions. Photographs taken inadvertently under bright sunshine with a ‘cloud setting’ have been re-adjusted afterwards based on memory and knowledge of the plants. Below are reproduced two of our best images (2017) of nearby almost identical plants — apart from the colour. Both these plants are ideal G. densiflora with over 100 florets, considerable height and and identical configuration of the flowers. One just happens to be totally white!Typical Gymnadenia densiflora characteristics:
•
Tall plants (50 cm+). Strong keeled basal leaves (not shown in these pictures).
•
Multi-flowered spike 40 - 100 or more. The white flower (BELOW) has many more buds yet to open.
•
Spur very long and very curved seen well in white specimen which is not yet so tightly packed.
•
Florets duplicate icons from research paper reproduced above. i.e. flowers are broader than they are high.
•
Sepals are simple, horizontal and parallel sided. White plant slightly drooping as spike may be fresher?
•
Lower lip has shoulders on side lobes.
Other species in Ireland:
This species (also known as the Dense-flowered Fragrant Orchid) is the main species found in Ireland and is particularly associated with wet acidic heaths or lake margins. Does not stand flooding and this may be a factor in its strange distribution in 3 very similar fields?English sample:
Gymnadenia conopsea is rare in Ireland and its distribution little known. It is a lime loving plant so places like The Burren or chalk hills in southern England would be more suitable locations for it. The specimen on RIGHT comes from the Chilterns and was photographed in early June. The photograph is small as we were photographing an exotic English specialty (not found in Ireland) at the time! Image comments: It is difficult to precisely determine species assignation here but the location is a clue. This plant was growing very near the top of a chalk hill in association with Pyramidal Orchids and Burnt-tip Orchids. It was a very dry exposed habitat and large numbers of specimens were flowering happily in the area. Also the flowering time and the colour is somewhat different from G. densiflora. Unfortunately none of the flowers in the image are yet fully open or facing the camera but it seems that this species is well recorded in the locality!
The Chilterns
A Burren site:
On the the 22nd July 2017 we visited this site in The Burren. It is a large
synclinal area of scrub and bare rock formed like a large shallow
amphitheater. A happy hunting ground for a variety of small but
interesting orchids. It was quite late in the season but here are some of the
more interesting species. All are Fragrant Orchids apart from the Bottom
Right image which is of an O’Kellys Spotted Orchid in full flower. This is put
in for comparison with the white Fragrant Orchid also found here.
Are these Gymnadenia conopsea as the limestone backdrop might imply?
Yes, we think so! The plants are very stunted scarcely more than 15cm
high. The site is very dry and alkaline and not suitable habitat for an acid
loving species. But G. conopsea is also known as the Chalk Fragrant Orchid!
It has very conspicuously lobed labellum with the side lobes very full and
delicately frilled. One character specifically refered to is the looseness of
the flowers which allow an observer to see right through the flowering
head. (See RIGHT) This is also a feature of the white specimen plant
ascribed to the species G. densiflora above but many other qualities
confirm our original identification. There is so much variation in this taxon,
whether we accept them either as a species or a subspecies?
However, the growth and colour of the plants shown here is very different
from the vast majority of specimens found at the Lough Gara site. (Maybe
it would be opportune to assess the pH at that location?) Growing location,
presence of water, aspect, have (we find) a considerable impact on how
various orchids grow and flourish. Within the Lough Gara site local
variability clearly exists reflecting whether an individual plant is well
watered or suffering from drought. At time of writing (July 2018) Ireland is
enjoying a very long spell without rain, drought like conditions but
somewhat alleviated by occasional mist and drizzle in the North West. This
seems sufficient to keep these late flowering orchids going but there are
several drought afflicted specimens in the same site. Severe damage was
done to early flowering orchids such as the Bee Orchid (Ophrys apifera) and
early Spiranthes romanzoffiana (Irish Lady’s Tresses) though these have
now recovered.
Interestingly we read that most Gymnadenia in Britain are diploid whereas
polyploidy is widespread among European populations. This too can cause
widespread alteration of colour and appearance (cytotype) and a
uniformity of appearance and ecology may well confirm a diploid (normal)
population such as the L. Gara Fragrant orchids?
We strongly recommend the following:
Günther's Homepage: Guide to European Orchids. (Great photographs of all Gymnadenia.)
Gymnadenia in Britain and Ireland: All aspects, habitat, morphology, genetics, mycorrhiza etc…
Mycorrhizal associates: Study of Fungi associated with G. conopsea group
Images and close up details of G.conopsea from The
Burren.
RIGHT
O’Kellys Spotted orchid, a variety of the
Common Spotted orchid. Growing
alongside Fragrant Orchids and shown
here to facilitate differentiation…
Sketch MAP:
We often show distribution on a much more detailed map, where there are no conservation issues. For this location we just want to show numbers and specific pattern of occurrence; there is something that particularly suits this species in one field? Numbers are down this year (85). Why? Winter flooding, recent hot drought conditions, etc?
This is the first of the 3 fields with a mixed collection of
Common Orchids and hybrids. The Fragrant Orchids are
in the furthest field in front of the dark green Reeds.
The water level in Winter floods is more or less
coincident with the rows of Hawthorn and Wild Rose
bushes. No orchids were found below the Winter ‘tide-
mark’ which is lowest in the 3rd field. i.e. more space for
Fragrant Orchids to prosper?
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Colour variation beside tractor trail into upper field.
The Study Site taken from eastern margin.
For more information on the
Chalk Fragrant Orchid you
can see the Site and some
more images on ‘The wild side
of Peterborough’ [MORE}
The site in question is in
Bedfordshire.