Orchis – albiflora

Albiflora orchids on Gotland

There have been a couple of botanical travel reports from Gotland with findings of white-flowered orchids, especially of Dactylorhiza incarnata. This year, I’ve finally visited this Baltic Sea island, in a quite warm and dry summer.

Such Dactylorhiza incarnata f. albiflora without any color hue have been quite rare – on my round trip by bike I’ve seen four plants. That translates into an estimated ratio of two or three per 1000 plants, which is quite the relation to be expected. Quite more often have been plants with a light yellow hue, although those could not always be addressed as the subspecies (or other taxonomic order) ochroleuca.

It was obvious that Dactylorhiza incarnata, possibly the orchid with the biggest population on Gotland, is occuring here in an marked color polymorphism – from white (very rare) to yellow (occasionally), light violet/pink (common) and the dark purple (common) flowers of the cruenta form which is sometimes viewed as a subspecies.

With Orchis mascula there have also been albiflora forms in the frequency to be expected from genetical mutations. In all those plants the pattern of purplish points in the flower lips has been preserved.

On a meadow near Oestergarn there was a beautiful white-flowered Gymnadenia conopsea among hundreds of plants..

Following a hint by Marco Klüber I also found an almost white-flowered Orchis spitzelii in a pine wood on the Northwestern coast. The color hue was still recognizable, the loss of pigments not as far reaching as here. But it’s still an indication that this orchid species also shows a genetical inclination to develop albiflora forms.

Albiflora couple in the valley of Kinzig

With Orchis mascula, the albiflora forms are not rare. But in many cases the pattern of violet points is preserved in the lips – even if the production of Anthocyanin is disturbed, the last reserves are obviously kept for this pattern. This year, a pair of Orchis mascula was flowering entirely white in the valley of Kinzig (in Hesse, Germany):

The leaves of these plants are unspotted, while the violet-flowered Orchis mascula often have intense spots.

Nearby, Orchis purpurea was beginning to flower. The third orchid species on this meadow in the “Schdänerer Weiberch”, as it is called in the Hesse idiom at the beginning of the path, is Himantoglossum hircinum. In May, the lizard orchid is just beginning to develop its inflorescence.

A bit further on the path, at the edge of a small forest, there was another albiflora form of Orchis mascula, also without any violet color in the flower, but with a marked green stigmatic lobe. The green hue is also preserved in the spur.

(with many thanks to Matthias Raschka for indicating me the location)

Albiflora abundance on Sardinia

There are two forms of albiflora mutations with orchids:

the spontaneous growth of a white-flowered form as the consequence of a genetical defect in the process of creating anthocyanine pigments, traditionally called a freak of nature, Occurence: 1-5 among 1000 plants
populations of white-flowered mutations as the result of an evolutionary adaptation to environmental conditions, e.g. the concurrence of other violet-flowered food-deceptive orchids, occurrence: 10 to 500 among 1000 plants

I’ve found both forms on the Sarcidano plateau, a central region of Sardinia.

On lengthy hikes between Láconi, Ortuabis und Santa Sophia I’ve seen only one single albiflora form of Orchis mascula subsp. ichnusae, with the crimson marking of the flower labellum still preserved:

Before, I had already seen a single Orchis anthropophora without its typical flower colouring, in the forest of Domusnovas, on southern Sardinia:

Much more frequently are the white-flowered forms of Anacamptis morio subsp. longicornu in Sarcidano. Respectively one third of the overall several thousand plants in this region has the dark violet colouring, a bright violet (or rose) colouring or are white-flowered.

You can’t find this accumulation of albiflora forms in other regions on Sardinia which I’ve visited, neither at Domusnovas/Iglesias nor in the North or at Monte Albo. There, Anacamptis morio subsp. longicornu are consistently flowered in the regular violet. The albiflora forms of Sarcidano possibly have an evolutionary advantage. In this region there are also many Orchis mascula subsp. ichnusae giving pollinators as bees the learning experience that there is no nectar in the spur at flowers with this colour and form. In the other regions Orchis mascula subsp. ichnusae was less common or not present.

new year greetings from Croatian island Korčula

Starting into 2015 I received a nice mail from Mirjana and Nebojša Jeričević living on the Dalmatian island of Korčula. They sent me photos of albiflora forms of five species, Orchis quadripunctata (above), Anacamptis pyramidalis, Himantoglossum robertianum, Dactylorhiza romana and Orchis italica. Especially interesting are those of Dactylorhiza romana. Those plants show some light yellowish hue but are not as yellow as the common yellow form of this bi-coloured species. They are are growing among violet forms and it might be assumed that they are plants whose flowers should have been violet but lost the anthocyanins pigments.

Orchis olbiensis – Andalusian chromatics

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.

Albiflora forms of Orchis in Austria

Two white flowered forms of Orchis are presented by Norbert Griebl in the latest edition of “Berichte aus den Arbeitskreisen Heimische Orchideen” (29/2012, 2, p.94-110). The contribution gives an overview of the seven Orchis species in Austria and shows their distribution maps. About Orchis spitzeli he notes: “In some years white or whitish plants appear at the location in Salzburg.” The paper has a photo of a second white-flowered plant, an Orchis mascula subsp. speciosa fo. albiflora. In the same edition of the “Berichte”, Adolf Riechelmann decribes his field trip to Ibiza and mentions an apochrome specimen of Ophrys dyris, found at the southern tip of the Mediterranean island. But the main article of the edition is contributed by Werner Hahn: In the footsteps of Christian von Steven. Searching orchids and pollinators in the Crimean mountains 2011 and 2012 – an exciting study of the orchid flora of the peninsula and as well as of a special chapter of the history of botany.

on the trails of Ignaz Friedrich Tausch

On the occasion of a visit to Prague I looked up some specimens at the Charles University Herbarium (PRC). In order to help a friend, I searched for the holotype of a plant which was described by the Bohemian botanist Ignaz Friedrich Tausch as Ophrys purpurea (Flora; oder, (allgemeine) botanische Zeitung. Regensburg, Jena 1831) – now regarded as a synonym of Ophrys apifera or as Ophrys apifera var. tilaventina. The holotype was said to be in the herbarium in Prague, so I searched several packages of Ophrys specimen there, with the much appreciated help of PRC’s curator Jan Stepánek.

The holotype of Ophrys purpurea was not there, but I found an interesting specimen collected by the French botanist Jean Michel Gandoger (1850-1926):

The description carries the information that Gandoger collected this plant in 1879 near Algier as Ophrys apifera f. elata, formerly described by Tausch as Ophrys purpurea:

At the end of my visit I searched a further package of specimens with dried Orchis plants – hoping to find a albiflora specimen. Instead I detected a specimen collected by Tausch as Jan Stepánek confirmed by examining the hand-written label with the nomber “1470” attached to the stipe of the plant:

A further label written by an unknown person has the information: “Orchis mascula L. vom berge Rhadisken bei Leitmeritz” – this information matches the catalogue of “Fundorte der Flora Boehmens nach weiland Professor Ignaz Friedrich Tausch’s Herbarium Florae Bohemicae alphabetisch geordnet von Johann Ott”, published 1859 in Prague:

So who was this Ignaz Friedrich Tausch? The Bohemian botanist was born on January 29th, 1793, in Udrči near Karlovy Vary. After his thesis about “De inflorescentia” (1835) he was director of the botanical garden of duke Canal de Malabaillas in Prague. He studied a broad spectre of plants and published “Bemerkungen über einige Arten der Gattung Paeonia” (1828) as well as his Flora Bohemiae (1831). Tausch was all his life rather poor, Stepánek told me. So he sold dried plants ot different herbariums. Tausch died on 8th September 1848 in Prague.

Albiflora studies on the Crimean Peninsula

Exploring the Crimean Pensinsula for orchids, species like Comperia comperiana, Steveniella satyrioides or Orchis punctulata are especially noteworthy. Albiflora forms, though, are quite rare in this Ukrainian region. Vladimir Isikov of the Nikita Botanical Garden told me that he has seen only three species with white-flowered forms: Orchis simia, Neotinea tridentata and Anacamptis morio ssp. caucasica (which he referred to as Orchis picta). Obviously there are no orchid species on the Crimean Peninsula heading to a direction which favours white flowering.

But near тылобое (Tylovoye) we found an edge of a forest with a group of 26 Orchis simia under a pine and 5 albiflora plants among them. In this small population there was obviously some kind of reproduction of the white-flowered plants.

Neotinea tridentata has a marked variability, as it is also noted by H. Kretzschar, W. Eccarius and H. Dietrich in their book „Die Orchideengattungen Anacamptis, Orchis, Neotinea“ (Buergel 2007, p. 206/207). On the Crimean Peninsula the dominant colour of flowers is light purple. I’ve found 3 white flowered plants, which led me to a rough estimate of 2 albiflora plants per 1000 Neotinea tridentata.

Among the Anacamptis morio, Orchis mascula, Orchis purpurea or Anacamptis pyramidalis seen on our 10-day-trip there have been no white-flowered plants. But in a forest near гончарное (Goncharnoye) there was an albino form of Epipactis helleborine.

Beyond the orchid flora I noticed white flowers of Polygala major, the endemic Onosma taurica and Papaver spec. Interesting was also a Polygonatum odoratum with half white leaves.

Colour influences pollinator behaviour

The Flower of the European Orchid

Form and function of the flower organs are the main focus of the new fascinating book The Flower of the European Orchid by Jean Claessens and Jacques Kleynen. Illustrated by great macro as well as microscopic photos this important opus presents a comprehensive description of the structure of orchid flowers with the different European genera. In a foreword, Richard Bateman writes: „No other family of plants can match the orchids for their sheer charisma“. But the excitement goes along with a certain scientific pain – Bateman stresses that there still remain major scientific uncertainties which „further torment us“ – among them questions of evolutionary adaptation.

The orchids’ strategies of fertilization are manifold and the book explains how the specific construction of the column (gynostemium) supports allogamy by pollinators or autogamy (self-fertilization). Especially intriguing are the strategies of Dactylorhiza, Orchis and other genera without any nectar in the spur. Claessens and Kleynen explain that the pollinators of Orchis mascula are „recently emerged, naïve bees or exploratory insects that have not yet learned that the flowers offer no reward” (p. 220). The authors also cite the study of L. Dormont, R. Delle-Vedove, J.-M. Bessière, M. Hossaert-Mc Key und B. Schatz about the presence of white-flowered Orchis mascula which underlines „the importance of visual cues for attracting pollinators“ (p. 220).

In the Dactylorhiza chapter the authors write: „Colour can also influence pollinator behaviour“ (p. 240). With regard to the red and the yellow forms of Dactylorhiza sambucina they refer to experiments showing that experienced bumblebees „preferred by far the morph that most resembled the rewarding plant on which they have fed previously“. Vice versa it may be presumed that there may be a form of evolutionary adaptation directed to develop visual cues which are different from non rewarding plants being abundant in a certain region – as it could be the case in Western Ireland with the many white-flowered forms of Dactylorhiza fuchsii on meadows with earlier flowering Orchis mascula.

Albiflora plants influence naïve pollinators

White-flowered orchid varieties are not just a “freak of nature” – they have quite obviously some biological function. A group of scientists in Montpellier in Southern France has found that the existence of albiflora plants in a population of Orchis mascula is connected with a much higher fruit set of the purple-flowered plants than in populations where there are no white-flowered Orchis mascula:

“Surprisingly, our study showed that the presence of co-occurring white-flowered individuals led to significantly higher reproductive success of nearby purple-flowered individuals (mean fruit set 27%), while white-flowered plants themselves had the same low fruit set (6%)”, the authors of the study – L. Dormont, R. Delle-Vedove, J.-M. Bessière, M. Hossaert-Mc Key and B. Schatz – wrote in their article in New Phytologist (2010) 185: 300–310. The flowers studied – overall 11 709 at 805 plants – showed almost the same increased fruit set when the researchers planted some ping-pong balls which mimic the white Orchis mascula inflorescences: “The effect was virtually identical in magnitude (fruit set increased from 6 to 27%), whether the nearby white-coloured object was an O. mascula inflorescence or a ping-pong ball.” The nearer a purple-flowered plant to the white colour, the higher was the fruit set developed due to a successful pollination.

The authors explain their surprising results with pollinator behaviour after visiting Orchis mascula who belongs to the food-deceptive orchids: “It seems plausible to suppose that after unrewarding visits to purple flowers, naïve pollinators probably avoid homogeneous populations of purple flowers, and may then preferentially orient to a different colour or to a colour contrast such as a mix of white and purple flowers.” Pollinators of Orchis mascula are bumblebees (Bombus, Psithyrus), solitary bees (Eucera, Nomada, Andrena, Apis) and the beetle Cetonia aurata.

The albiflora varieties are quite rare in the populations studied in Southern France: The authors counted 0.9 to 1.4 percent in different populations. But this is much higher than the percentage which could be assumed in the case of spontaneous mutations affecting floral pigmentation genes with an average of just 0.1 percent. Regarding the higher percentage of albiflora varieties with Orchis mascula the authors state that “it is unlikely that such high frequencies could be the result of repeated spontaneous mutations alone” – and this should also apply to the case of other orchid species with a higher percentage of white-flowered plants like Anacamptis morio or Dactylorhiza fuchsii in Western Ireland.

The white-flowered Orchis mascula themselves have only a low fruit set, but they “help” the purple-flowered plants of their species to be pollinated. “In O. mascula, the presence of whiteflowered variants might be regarded as an adaptation that benefits the purple-flowered relatives of white-flowered morphs, rather than providing a direct benefit to whiteflowered individuals”, the authors wrote and assumed that there is some “mechanism of kin selection” responsible to grant a higher percentage of albiflora plants.

The scientists in Montpellier are pursuing their research with other species as well. Laurent Dormont wrote me that they have also studied white-flowered plants of Calanthe sylvatica on the Caribbean island of La Réunion (the results to be published in Plant Systematics and Evolution and also the floral volatiles of white-flowered orchis species.