WILD TERRESTRIAL ORCHIDS
It is always exciting to hunt for and find rare wild species, but it is particularly thrilling, at least for me, to come across wild terrestrial orchids, above all because oftheir rarity, beauty and variety of form but, as one gets to know more about them, also because of their complexity, their ongoing evolution and the extraordinary goals they have already achieved.
But first things first. Orchidaceae is the second largest plant family after Asteraceae and because of their adaptability orchids are to be found in practically every environment on Earth, except for deserts and glacial ice-fields. The wild orchids found in Italy are called geophytes, because they have an underground root system that anchors the plant and, more importantly, contains the substances that nourish the gemmae contained in it. They are herbaceous perennial plants, the stem or caulis dries out and dies down at the end of every vegetative cycle and, unless they are picked or damaged, before they completely dry up the organic substances sink down into a new tuber, which will replace an old and exhausted one.
In this way the gemma contained in the new tuber is strengthened and produces a new plant.
Of course, we must not uproot wild orchids in order to examine or handle the roots and young plants must be respected in their entirety. Specialist texts describe in detail the root system of each species. European orchids, all of which are terrestrial, can live several years and flower briefly once a year in spring or early summer. (In Italy only one species, Spiranthes spiralis, flowers in autumn).
Orchids have a single, straight unbranched stem, which is green, sometimes shaded with red-purple and can be between a few centimetres and one metre tall. The inflorescence may have few or many flowers and may be densely or sparsely covered. Near every flower there is a small modified leaf, called a bract, which is important because its shape or colour help to identify the species.
Orchid leaves differ from species to species, but are generally green, sometimes with dark markings. They may be grouped together in a basal rosette or be distributed along the stem.
The leaves of Listera ovata are distinctive – there are two large opposite ovate leaves with conspicuous veins, positioned about one third the way up the stem. One notices them before the inflorescence, not least because the flowers are yellowy-green and sparse.
Orchid flowers consist ofsix parts called tepals; three outside ones ofthe same colour and shape and three inner ones, two ofwhich are identical, whilst the third is completely different, being either broader or longer than the others, often with a bizarre shape or a different colour, or conspicuous spots or stripes and is usually trilobate. This strange tepal is called the lip. There is a curious phenomenon, called resupination, characterising the lip of almost all our native orchids: when the flowers are still small buds the lip faces upwards but as they develop and before opening they rotate through 180°, so that by the time the flowers open completely the lip is facing downwards. This allows pollinating insects to notice it and land on it more easily. In a number of species more or less sophisticated “traps” attract and exploit insects for pollination in order to produce seeds. At the same time the flowers produce nectar, which insects love. It is usually found in a hollow extension of the calyx or corolla called a spur. In order to reach it insects have to reach the heart of the flower, thereby brushing past parts rich in pollen. When the spur is particularly long, for example in Anacamptis pyramidalis, only butterflies with a proboscis can suck up the nectar, which means that only certain types of insect are selected. Listera ovata, already mentioned because of its pair of large leaves and the inconspicuous inflorescence, attracts various species of insect by producing plentiful and exquisite nectar, although it is not contained in an inconvenient spur but flows invitingly along a furrow on the lip.
Furthermore this orchid, which can live more than twenty years, produces a viscous liquid that sticks onto the insects’ heads the pollen-mass which might otherwise fall off. The flowers of the genus Ophrysdo not produce nectar, instead insects are attracted by the shape of the lip, which closely resembles a female insect.
Confused by this and by pheromone-like substances emitted by the flowers male insects, mainly hymenoptera, try to couple with the flowers and in the process pollen sticks to their heads or abdomens. As they fly around they are seduced by other fake females and they pollinate more and more flowers during their pseudo-copulations. After all this excitement and all these vain attempts at coupling it is easy to imagine them huddling on any old leaf at the end of the day, maybe with a slight headache!
In any event, where pollinating insects have almost disappeared because of environmental changes our native orchids have evolved towards self-pollination.
Some species avoid cross-pollination by completing the whole process inside the flower almost without opening up at all, for example Limodorum abortivum.
Recently I watched an Ophrys apifera over several days and one morning I found that it had shed its pollen and transferred it to the stigma. It is the only species to behave in this way.
If there are no adverse climatic factors, human intervention or other problems, the fertilised ovaries of the flowers produce large numbers of tiny seeds that are dispersed in the wind. It would be nice to be able to sow terrestrial orchid seeds, but for a new plant to form and develop from a seed is a pretty rare event. In order to germinate a seed requires symbiosis with a special fungus that supplies the seed with substances that it lacks, in a perfectly balanced relationship between the two.
This relationship is called mycorrhiza and is explained in precise detail in botanical textbooks. The same goes for the phenomenon of hybridisation – whether or not produced by chance – and other unusual characteristics of Italian orchids.
I photographed an example of non-pigmentation in a small clump of Ophrys sphegodes. In the midst of some normal specimens there were plants with sand-coloured flowers. Unfortunately, when I went back two days later to take a closer look I was shocked to find that some disrespectful person had removed almost all of them, both coloured and colourless specimens, and had even dug up plants, leaving holes in the ground. I will of course return in the next flowering season to see what is left.
Let’s hope for the best.