LESSER BUTTERFLY-ORCHID

Platanthera bifolia

(Formerly: Habenaria bifolia)
Orchid Family [Orchidaceae]

month8may month8jun month8june month8jul month8july

status
statusZnative
 
flower
flower8white
 
inner
inner8green
 
morph
morph8zygo
 
petals
petalsZ5
 
type
typeZspiked
 
type
typeZspurred
long
stem
stem8round
 
stem
stem8fluted
 
smell
smell8scent smell8perfume
scent

1st June 2004, Ireland. Photo: © Phil And Ann Farrer
Between 15 to 55cm high with less than six small stem leaves and two shiny-green, pointed basal leaves, which are shorter but broader particularly on the hill-form of the plant.


1st June 2004, Ireland. Photo: © Phil And Ann Farrer
About 25 well-separated white flowers which are tinged yellow-green in places. The flowers have two triangular white wings and a short greenish parallel tongue/lip, which look vaguely like a Small-white Butterfly, hence the moniker.


7th June 2009, Lot Valley, France. Photo: © Hester Coley
The hood is triangular and loose comprising an upper sepal and tow short white petals either side. On this specimen the hollow spur sticking out the back of the flower seems unusually long.


7th June 2009, Lot Valley, France. Photo: © Hester Coley
The opening into the spur behind the hood is obstructed by the pollinia, which in Lesser Butterfly Orchid are almost parallel to each other but separated. The pollinia are the fawn-coloured objects in the centre and they present the yellow pollen to visiting insects. The two yellow blobs nearer the long central lip are the viscidium (not the organs bearing pollen). The only definitive way to tell the two Butterfly Orchids apart are from the separating distance of the pollinia in the centre: Wide apart but nearly parallel for Lesser Butterfly-orchid; or wider apart at the bottom and coming together at the top and nearly touching for Greater Butterfly-Orchid. No other characteristic is reliable.


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks Dales. Photo: © RWD
The basal leaves are just two opposing wide lanceolate leaves. The flowers are relatively large, but fairly few in number, pointing in various directions around the upper third of the stem.


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks Dales. Photo: © RWD
The spike of flowers which have white 'petals' tinged lime-green in places.


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks Dales. Photo: © RWD
Some flower buds at the top have yet to open. (The pink flower on the right is Bird's-eye Primrose)


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks Dales. Photo: © RWD
Attached onto the long parallel-sided


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks Dales. Photo: © RWD
The ovary double as the flower stem. Three white petals in a triangular arrangement. The lower lip is longer and narrower and off-white (tinged lime-green). Behind the flower a very long hollow tube projects backwards. It is white nearer the flower becoming greener nearer the tip.


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks Dales. Photo: © RWD
The spur at the back is a hollow tube sealed at the rear and which contains nectar which is presumably the substance which gives Butterfly Orchids their pleasant odour. Here you can see droplets of the fluid (visible in most others too, for the tube is translucent).


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks Dales. Photo: © RWD
Two extra 'petals' are shorter than all the others and cup around the head as if praying. There are thus 6 'petals' all told. It is night-scented but the odorous compounds differ from those of the Greater Butterfly-Orchid. The pollinating insects are thus mainly moths such as the Pine Moth, Small Elephant Hawk-Moth and Elephant Hawk-Moth.


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks Dales. Photo: © RWD
Two broad lanceolate leaves at the base of the plant.


Easily mistaken for : Greater Butterfly-Orchid (Platanthera chlorantha) but that has the two pollinia further apart and splayed out sideways to each other rather than the strictly parallel pollinia of Lesser Butterfly Orchid, this last property being the main differentiating feature between the two.

Hybridizes with : Greater Butterfly-Orchid (Platanthera chlorantha) to produce Platanthera × hybrida.

Un-like Greater Butterfly-Orchid it will also grow in very acidic soils. It is found in grasslands, woods (especially of Beech in Southern England), up to 1200 feet in height on damp hill pastures, moorland, wet heaths, or tussocky marshy ground and near stream flushes which produce less acidic parts of bogs. Much more infrequently found on damp pastures on hills or in chalk grassland and deciduous woods. The spur at the rear of the flower is a long 13-23mm, but usually shorter than that of the 19-35mm of Greater Butterfly-Orchid.

The flower spike has 5-25 flowers (against the 10-40 of those of Greater Butterfly-Orchid. It is usually white-flowered, but if it is growing in a bog then the flowers will be greener.

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 bifolia  ⇐ Global Aspect ⇒ Orchidaceae  

Distribution
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genus8Platanthera
Platanthera
(Butterfly-Orchids)

LESSER BUTTERFLY-ORCHID

Platanthera bifolia

(Formerly: Habenaria bifolia)
Orchid Family [Orchidaceae]