Orchids “adapt” to colour preferences of pollinators

This hypothesis has been formulated by Hannes Paulus in a contribution for the latest edition of the Journal Europäischer Orchideen (Hannes F. Paulus: Zur Bestäubungsbiologie der Gattung Ophrys in Nordspanien: Freilandstudien an Ophrys aveyronensis, O. subinsectifera, O. riojana, O. vasconica und O. forestieri. J. Eur. Orchideen. 49 (3-4): 427-471).

In this article the author studies both populations of Ophrys aveyronensis in Southern France and Northern Spain – the last one termed as Ophrys aveyronensis subsp. vitorica. According to Paulus it is just one species, because both are pollinated by the bee Andrena hattorfiana.

Paulus points to the fact that this bee is specialised on the widow-flower (Knautia). The pink inflorescence of this plant has the same colour as the perigone, i.e. the sepals and petals, of Ophrys aveyronensis. The expert of Ophrys is stating: It can be expected that this is not just a mere chance but an adaptation to the main nourishing plant of the pollinator. Knautia shows at the same time more deeply pink flowers as flowers tending to white.

This evidence is confirming the approach to also look for other plants when we search for reasons why albiflora forms of different orchid species are more often in certain places.

Orchis olbiensis – Andalusian chromatics

orchis_olbiensis

Orchis olbiensis has a colourful and a light variety, as it is stated by Kretzschmar/Eccarius/Dietrich in “Die Orchideengattungen Anacamptis, Orchis, Neotinea” (Buergel 2007, p. 322). The light variety has flower colours between rose and almost white – with a colourful lip pattern contrasting to the light background. The white-flowered plant comprises almost half of the populations in Spain, the authors observed – quite in difference to the almost purplish flowers of Orchis olbiensis in France.

Five years after visiting Orchis olbiensis for the first time in Southern France, I had now the chance to study Orchis olbiensis in Southern Spain, in the province of Malaga. Though in mid-April I’ve been quite late for this species, I found two albiflora forms of Orchis olbiensis in the limestone formation of the Torcal, near the small town of Antequera. The greater plant had nine almost white flowers with the fine purplish dots still conserved. In this habitat there were also growing Anacamptis papilionacea, Ophrys scolopax and Orchis mascula subsp. laxifloraeformis.

orchis_olbiensis_2

Ophrys speculum f. flavescens

In the latest issue of “Berichte aus den Arbeitskreisen Heimische Orchideen” (27/2, 2010), Klaus Boie presents a rare hypochrome form of Ophrys speculum in his article about orchid-findings in western Andalusia (p.117-122). He found this forma flavescens in the Spain region of Andalusia, in the midst of a large group of Ophrys speculum, as he writes.

The marking of the labellum is just white, the other parts of the flower are yellowish-green. As with other hypochrome forms of Ophrys, the photo shows a total lack of anthocyanins. But the flower has still chlorophyll embedded – in contrast to albiflora forms of other orchid genera with their their pure white flowers. Probably the Ophrys species need the flower’s contribution to photosynthesis, because the leaves of the rosette are withering at an early stage.