Friday, 4 September 2009

Early Marsh Orchid

Early Marsh Orchid (Dactylorhiza incarnata)

The Early Marsh Orchid is very widely spread across Britain though it does not occur in abundance and has been lost from many areas. There are five subspecies of Early Marsh Orchid which have different coloured flowers and occur in different habitats.

Dactylorhiza incarnata subspecies incarnata is found in alkaline fens and marshy meadows. Its flowers are a unique shade of flesh or salmon pink unlike that of any of the other orchids found in Britain. The only other flower in Britain I can think of which is almost this colour is Tall Ramping-Fumitory which has pinnate leaves and could not be mistaken for an orchid. So perhaps D.i. subspecies incarnata is one of the few flowers that could be identified here by its colour alone. The flower spikes are often satisfyingly chunky, though sometimes it grows in leaner spikes.

Last year I found D. i. subspecies incarnata in a dune slack at Formby Point, Lancashire. Dunes might not be the first place you think of as alkaline or marshy. Chalk is a very ancient deposit of shells. Calcareous shell debris can collect on dunes and in the hollow between dunes - i.e. the Dune slack – which can be damp enough to support plants that require a damp habitat if part of the hollow falls below the water table.

Common Fragrant Orchid

Common Fragrant Orchid (Gymnadenia conopsea)

Formerly the Common Fragrant Orchid, Marsh Fragrant Orchid and Heath Fragrant Orchid were classified together. They were then separated into three sub-species before their current recognition as three distinctly different species.

The species do align with the habitats indicated by their name grassland in the case of the Common Fragrant Orchid, and marsh and health land in the case of Marsh and Heath Fragrant Orchids. However these habitats can overlap so details of the features of plants must be used. While there are differences between minimum and maximum heights of plants this is not an ideal defining character to use because their height ranges overlap. The characteristic I have found most useful is the differences in form of the lower lip of the flower. Look at this feature on several different plants in a colony to make sure that you are not using the one odd one in a group. There is some additional complexity in identification because Fragrant Orchids readily hybridise with each other leading to intermediates which are hard to identify because of similarity and because the defined identification characteristics are still being developed for these species.

Common Fragrant Orchid is found mainly on dry unimproved grassland on calcareous soils. It requires some grazing of the grassland to limit the development of scrub, but intensive grazing does not support this species so maintenance of its habitat is a fine balance.

It flowers from mid May to late July and the flowers occur in shades of pink from a near purple pink through to pale pink and with white varieties present too.

I scrabbled around the top of the North Downs above Wye and found a couple of single tatty plants. Heading straight down the steep slope crossed by terracettes I found hundreds of Common Fragrant Orchids. It was a still sunny day and the fragrance rose up from the flowers so strongly there was not need to stoop to smell them.

Common Twayblade

Common Twayblade (Neottia ovata)

Perhaps the Common Twayblade has a Nordic origin, courtesy of Nordic invaders, to its name with its current name in Swedish being TvĂ„ Blad meaning the same as the English word Twayblade – two leaves. This plant has two leaves clasping the base of the flower stem, or sometimes just two leaves present where there is no flower stem. Occasionally you might find the odd plant with three to five leaves, much as you might find a four-leaved clover. The stem is hairless below the two main leaves and lightly downy above the leaves. If you catch this plant early in the morning or late in the afternoon these tiny hairs give it a golden halo. Technically there are a few very small leaves higher up the stem above the main pair.

The Common Twayblade flowers from late April until early August. It is called Common because it is so widespread throughout Britain. Its wide spread is due to its resilient and adaptable nature. It does not occupy one specific habitat type and can be found in most habitats from woodland, grassland to dune slacks. Two common features in its distribution is that grows predominantly on calcareous substrates and will only tolerate mildly acidic soil. It also grows in areas that are relatively undisturbed – ancient woodland, unimproved grassland, heathland etc. Despite its wide distribution this plant is currently absent from 30% of its historical range, which would seem to be linked to the general loss of habitat that has occurred.

The flowers are the kind which a lot of people pass by unless directed to look more closely. The flowers are small and greenish, on closer inspection they are clearly shaped like a small person. The plants can be found singly or in dense clumps. These clumps arise from vegetative reproduction where shoots from the rhizomes develop into new plants. It takes from 7 to 20 or more years for a plant to reach maturity from seed. This slow developing is accompanied by longevity, plant have been known to exceed 40years of age. The flowers are so small that they can only be pollinated by small insects. Attracted by nectar these insects set of a sensitive trigger mechanism in which rapid secretion of a sticky quick drying liquid which sticks the pollinia onto the insect. This mechanism is highly efficient and results in high rate of seed setting.

This year I found Common Twayblades growing in ancient woodland at the base of the North Downs above Wye in Kent. Last year I saw them growing around pitches on a campsite in woodland in the Lake District and 6 weeks later in dune slacks on the north coast of Scotland.