GREATER BUTTERFLY-ORCHID

Platanthera chlorantha

(Formerly: Habenaria chlorantha) and Habenaria virescens)
Orchid Family [Orchidaceae]

month8may month8jun month8june month8jul month8july

status
statusZnative
 
flower
flower8bicolour
 
flower
flower8white
 
inner
inner8green
 
morph
morph8zygo
 
morph
morph8peloric
 
petals
petalsZ4
 
type
typeZspiked
 
type
typeZspurred
v.long
stem
stem8round
 
smell
smell8sweet
sweet

June 2011, Aston Clinton, Aylesbury, Bucks Photo: © Phil And Ann Farrer
20 to 60cm tall. Two large elliptical basal leaves, shiny on the upper surface and up to five smaller pointed stem leaves. White flowers in a cylindrical spike on the upper third of the single stem. Other orchids nearby.


Sprotborough, Yorkshire. Photo: © John Phandaal Law
Flowering spike is open and not dense.


10th May 2009, Lot Valley, France. Photo: © Hester Coley
Between 10 to 40 white flowers in a spike


July 2007, Isle of Skye, Scotland Photo: © Phil And Ann Farrer
Flowers born on short, slightly bulging and drooping ovaries. All sepals are white; two lateral ones which are wavy-edged, and a smaller upper central one.


17th May 2009, Lot Valley, France. Photo: © Hester Coley
Ovaries are s-shaped, fluted, twisted and green, with the flower at the end.


June 2011, Aston Clinton, Aylesbury, Bucks Photo: © Phil And Ann Farrer
The tongue is long, narrow, tapers to a rounded end and is white near the sepals merging into green at the tip.


Sprotborough, Yorkshire. Photo: © John Phandaal Law
The tongue is semi-translucent in the middle where white and green meet.


5th June 2012, near Gourdon, Lot region of France Photo: © Kelly Finney
The well-curved spur behind each flower is an enormously long 18-27mm, possibly the longest spur of any spurred flower in relation to the size of the flower itself. Short leafy, triangular-shaped green bracts (centre) are in the axils where drooping ovary meet main stem.


Sprotborough, Yorkshire. Photo: © John Phandaal Law
The long spur tapers from white to green at the blunt pointed end and curves slightly upwards.


Sprotborough, Yorkshire. Photo: © John Phandaal Law
Lateral sepals are wavy-edged and spread outwards, then downwards at the blunt tip. Two narrower upper petals, together with the single upper sepal form a cowl or hood at the top. The 8-12mm long narrow lip is translucent especially where it fades from white to pale green at the tip, which is un-divided.


5th June 2012, near Gourdon, Lot region of France Photo: © Kelly Finney
The two pollinia are set wide apart at the opening of the spur, which is hollow throughout its length. The pollen is yellow and on diverging stamens.


Sprotborough, Yorkshire. Photo: © John Phandaal Law
View of pollinia within. Yellow pollen each side at the bottom of the hood.


June 2011, Aston Clinton, Aylesbury, Bucks Photo: © Phil And Ann Farrer
Two elliptical basal leaves.


Easily mistaken for : Lesser Butterfly-Orchid (Platanthera bifolia) but that has the two pollinia closer together and parallel to each other rather than splayed out sideways.

Confusion: Aberrant flowers of Greater Butterfly-Orchid are fairly frequent, some lacking both spur and tongue, others without lateral sepals but with a sepal-like tongue. Yet others have a spur but no tongue. Sometimes all three sepals resemble tongues.

Hybridizes with : Lesser Butterfly-Orchid (Platanthera bifolia) to produce Platanthera × hybrida.

Peloric Greater Butterfly-Orchids have been mis-identified as hybrids with Small-White Orchid (Pseudorchis albida). Peloric aberrations are where the normal zygomorphic symmetry is broken by the addition of other elements so as to resemble actinomorphic (radial) symmetry. However, all Orchids nominally possess zygomorphic symmetry (bi-lateral symmetry).

No relation to : Butterfly-Bush, Alternate-Leaved Butterfly-Bush, and Weyer's Butterfly-Bush and [a plant with similar name].

Habitat: in Woods on heavier soils beneath chalk hillsides, but in the north also grassland, usually on well-drained alkaline soils and downlands, old pastures and upland hay meadows. Sometimes in calcareous sand dunes. Only occasionally found on slightly acid moorlands.

Smells strongly sweet and slightly of vanilla, particularly at night. The white flowers are highly reflective, very conspicuous in moonlight. It is pollinated by moths, in particular the Silver-Y Moth and the Small Elephant Hawk-moth, setting seed in 70% to 90% of the capsules. The spur at the rear of the flower is very long.

ODOROUS COMPONENTS OF THE NECTAR

The flowers smell more strongly (of vanilla) than do those of Greater Butterfly-Orchid and they also smell differently because they contain a different set of aromatic compounds:

Lesser Butterfly-Orchid contains the following compounds as odour components of the nectar:
β-Ocimene 9.0%
1,2-HexaneDiol-Benzoate 15%
Santolina Triene 19.5%
Nerol 5.7%
α-Carene 0%
Benzyl Acetate 0.5%
Lilac Adehyde 0%
Lilac Alcohol 0.2%

Whereas
Greater Butterfly-Orchid contains the following compounds as odour components of the nectar:
β-Ocimene >0%
1,2-HexaneDiol-Benzoate 0%
Santolina Triene 01%
Nerol 0.5%
α-Carene 15.6%%
Benzyl Acetate 0.01%
Lilac Aldehyde 15.6%
Lilac Alcohol 2.6%


β-Ocimene comes naturally in two slightly differing isomers, the cis- form and the trans- form. They are usually made together but not necessarily in a 1:1 ratio. [α-Ocimene occurs in neither Lesser nor Greater Butterfly Orchids]. The various Ocimenes are all oils with a delightful scent and used in perfumes but they are unstable in air as is the similar Myrcene (which does not occur in these orchids). Ocimene is derived from the Ancient Greek name for Basil which is κιμον. Ocimenes have anti-fungal properties and are thought to act in plant defence, they are harmful if swallowed, irritating to skin and eyes and toxic to aquatic organisms.



Nerol is another monoterpenoid found in the essential oils of many plants such as Hop and the non-native Lemongrass and is also used in perfumery. It is isomeric with Geraniol. Nerol readily loses water to become the cyclic monoterpene Limonene, which has two stereoisomers; the racemic mixture of which is called DiPentene.

Santolina Triene is also found within a Mugwort [specifically the non-native Santolina Yarrow (Artemisia santolina] and also plants from the Sanotlina genus which are small evergreen shrubs found mainly in the western Mediterranean region.



Both Lilac Alcohol and Lilac Aldehyde are found in Lilac flowers, hence their names. They are used in the perfume industry. The Lesser Butterfly-Orchid contains no Lilac Aldehyde and very little Lilac Alcohol, whereas Greater Butterfly-Orchid contains much more. They both contain a Furan moiety (the five membered ring with oxygen) which makes them toxic. (Your Author thinks it amazing how many chemicals used in perfumes are toxic but the folk putting them on their skin seem unaware of this fact).

Because there are 3 chiral centres on the Lilac Aldehyde molecule, there are 23 = 8 differing stereoisomers of Lilac Aldehyde with odour thresholds varying from 0.2ng to 22ng, each smelling slightly differently such as 'sweet and flowery', 'fresh and flowery', 'flowery' and 'pleasant, flowery and fresh'.

There are also 3 chiral centres on the Lilac Alcohol molecule and thus the same number (8) of differing stereoisomers, but this time the odour threshold varies from 2ng to 100ng and the smell from 'green, grassy and fresh', 'sweet', 'flowery', 'odourless', 'flowery, sweet with body', 'herbaceous and slightly flowery' to 'sweet and flowery'.

In both cases your Author knows not which stereoisomers are present in either of the two Butterfly-Orchids.


Benzyl Acetate is a pleasantly sweet-smelling ester which is also found in the flowers of Jasmine (a genus of vines and shrubs in the Jasninium genus of the Olive family (Oreaceae) which are native to tropical and warm regions of Eurasia). It is used in perfumes and cosmetics and also as apple and pear flovourings in foodstuffs. Various Orchid bee species find the odour attractive and gather it in order to synthesize other pheromones for itself.



  Platanthera chlorantha  ⇐ Global Aspect ⇒ Orchidaceae  

Distribution
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 BSBI maps
genus8Platanthera
Platanthera
(Butterfly-Orchids)

GREATER BUTTERFLY-ORCHID

Platanthera chlorantha

(Formerly: Habenaria chlorantha) and Habenaria virescens)
Orchid Family [Orchidaceae]

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