Orchid (Orchis)

By | October 26, 2017

Orchid (Orchis)

Tubers 2, spherical or ovoid. Stem usually with a rosette of leaves at the base, less often all covered with leaves. The tallest leaf usually tufts the base of the inflorescence. Multiflorous inflorescence, usually quite dense. Flowers of various sizes, turned by 180 °, lip directed downwards, with a pronounced spur at the base. The remaining petals are usually tucked into the helmet or both outer sides tilted back. Pituitary glands of different sizes, membranous, thin. Stamen straight, with a narrow coupler. Rostellum z 2, fused pouches, enveloping 2 bonnets. Green pollen. Oval birthmark.

Pillar of the orchid genus (Orchis) seen from the side (a) and the front (b) and pollinia (c).

The genus includes approx 30-40 species, which grow almost all over Europe, in the Mediterranean and adjacent areas of the Middle East. Closely related species from North America and the Far East are usually separated into separate genera. It was served from Poland 9 species. One of them, three-tooth orchid (Orchis tridenlata Scop.) it is probably an extinct species, the second - a stinking orchid (O. coriophora Linn.) - threatened with extinction.

Most species of the genus orchid grow in fresh or dry meadows, sunny slopes and in thickets, usually in soils rich in calcium carbonate.

This genus includes species, which have adapted to different pollination methods.

One of them is found at Orchis papiliortacea Linn., species growing in southern Europe. Its flowers are relatively large, pink or red tinged, with a darker nerve mesh. Big, the flat lip is positioned almost perpendicular to the inflorescence axis. It is an attractive meeting place for insects. Observed, that some of them try to mate on it. It is therefore the first step towards pollination through pseudocopulation. This type of pollination is effective, when insects of both sexes can meet on the flower frequently enough, and, when their position during copulation will enable simultaneous pollination of the flower, by the way. The next stage in the evolution towards pollination in this way is O.galilea Schlecht. from the Middle East. It is only pollinated by male Lossioglossum marginatum, although the females in the environment, in which this orchid grows, are just as common. Its flowers smell intensely of musk. Males attracted by this smell, which probably stimulates them, they make quick movements near the spots in the central part of the lip. At this time, it is also dusty.

Out of 30-10 species of the genus orchid, only two – foul orchid (O. coriophora Linn.) and closely related to him, O. sanctum Linn. – offer insects a reward for pollination in the form of nectar. In both of them, the nectar is stored in the spur. Both are also pollinated by the same insect species.

Most species of orchids' use” for pollination, insects usually attracted by other honey plants, "Imitating" the latter in various ways. E.g, middle eastern O. israelitica Baum and Dafni is similar in color to Belleralia flexuosa (Liliaceae). Both species bloom at the same time, both also grow in similar habitats and are pollinated by the same species of insects (Eucera clypetala, Acinia sp.). Interestingly, when in the position of O. israelitica nee rośnie flexible Urgenia, the number of fruits produced by this orchid is dropping sharply. So we have a perfect example of mimicry here, that is, the imitation of one plant by another, not closely related to her. We observe a similar phenomenon in our pale orchid (Orchis pallens Linn.), which uses spring peas as the "reference" species (Lathyrus vernus) and is pollinated by the same insects, mainly bumblebees.

Yet another way of attracting and using insects has developed in female orchids (O. morio Linn.) and male (O. mascula Linn.). Both bloom in spring, so in the period, when most of our myo-additive plants are just entering the flowering phase. The red color of both orchids makes, that they are visible in the meadow from a considerable distance. They both smell intensely thanks to the emission of the so-called. terpene derivatives. They are pollinated by young ones, inexperienced bumblebee queens and male Eucera lon-gicornis, patrolling the area for food. Insects after a few, in a dozen or so days they learn to recognize false “food sources” and avoid orchids. However, these few visits are enough to pollinate a few flowers and ensure the continuity of the species. The poor specialization of both of these orchids causes, that they easily form hybrids with other species.

As can be seen from this cursory review, species of the genus orchid have in the course of evolution adapted to different pollination methods.

Let's think about it, how pollinia is removed from the rod when an insect visits. Well, both caps of species of this genus are covered with a bag. The insect sliding into the spur, he tilts his head backwards, covering the birthmark with it. Therefore, a barrier is created that minimizes the possibility of self-pollination. When it moves out of the spur, the insect catches its hairs on sticky hooks and takes them with it. The pollen handles dry very quickly and bend forward. At the same time, the bent bag covering the birthmark dries up and "makes" its surface available for other pollinia. When visiting an insect, properly positioned pollinia will easily stick to a sticky birthmark.

The key to determining the species of the genus orchid (Orchis) in Poland.

Leave a Reply

Your email address will not be published. Required fields are marked *