Limodorum abortivum: Albiflora form (left; Photo: N.Griebl) and common form (right)

Limodorum abortivum is one of the rarest albiflora forms of orchids. Sometimes, literature is mentioning the existence of white flowering plants, e.g. Horst Kretzschmar states in his new “Die Orchideen Deutschlands und angrenzender Laender” (Wiebelsheim 2008), p.163: “In Southern Europe, there is a broad variation of flower colours, from white to purple to red, these colours have not been observed in Germany up to now, though.”  Norbert Griebl in Austria has sent me a photo of an albiflora form he found in northern Greece. He observed that the plant has a green stem and green sheathing leaves, “which prooves that Limodorum is not totally living saprophytic” (=myco-heterotrophic).

Compared with the violet stem colour of the regular form the green colour of the stem is indead striking. The existent chlorophyll is obviously covered by dominant anthocyanins. When these purple pigments are absent – as it is the case with the albiflora form – the green chlorophyll colour becomes clearly visible. A study published in 2006 (M. Girlanda, M. A. Selosse, D. Cafasso, F. Brilli, S. Delfine, R. Fabbian, S. Ghignone, P. Pinelli, R. Segreto, F. Loreto, S. Cozzolino and S. Perotto: Inefficient photosynthesis in the Mediterranean orchid Limodorum abortivum is mirrored by specific association to ectomycorrhizal Russulaceae. In: Molecular Ecology 15, 2006, S. 491-504) recognizes the existence of chlorophyll but stated that Limodorum abortivum’s photosynthesis “was found to be insufficient to compensate for respiration in adult plants”. It would be interesting to know how the albiflora orchid is behaving in this regard and if it is also dependent on nutrition by fungi.

Today, 200 years ago, Charles Darwin was born – his vivid interest in varieties of animals and plants has led him to the insights of evolution: Species are not created once and forever but are rather the result of a process, which is partly still continuing. Especially the relatively young family of orchids is still in the midst of its development, and nature is trying to go new ways. One of them are colour variations like white orchids.

In his book about “The various contrivances by which orchids are fertilised by insects” (1862, 2. Auflage 1877), Darwin studied the structure of orchid flowers in relation to their pollinators. About Platanthera chlorantha (which he called Habenaria chlorantha) he wrote, that they are pollinated by moths – due to their long spur filled with nectar and an intense scent at night: “The remarkable length of the nectary, containing much nectar, the white colour of the conspicuous flower, and the strong sweet odour emitted at night, all show that this plant depends for it fertilisation on the larger nocturnal Lepidoptera.”(p.85). In a famous forecast Darwin estimated that there must be a pollinator in Madagascar matching the orchid Angraecum sesquipedale which has a spur with a length of 25 cm: “In Madagascar there must be moths with probosces capable of extension to a length of between ten and eleven inches!” (p. 198). In 1903, 41 years later, the appropriate butterfly was found, Xanthopan morgani.

The magazine of the Arbeitskreise Heimische Orchideen (AHO) has an article of Norbert Griebl in its latest edition giving an overview about the Dactylorhiza species in Austria. His contribution presents two photos of white varieties – a Dactylorhiza traunsteineri, the photo taken at lake Kochel in Bavaria,and a bright flowering Dactylorhiza incarnata, which is defined als Dactylorhiza incarnata f. ochrantha- with a yellowish accent in the lower part of the inflorescence but not as yellow as Dactylorhiza incarnata ssp. ochroleuca – Griebl views this taxon not as a subspecies but as a species of its own, since he argues that there are almost none hybrids between incarnata and ochroleuca.

In an article about maintenance of biotops in Rhineland-Palatinate Juergen Passin mentions a habitat near Vallendar on the Rhine “Orchis militaris, also var. albiflora”.