Notes on Epipactis aff. guegelii

A deviating morph closely related to Epipactis helleborine (L.) Crantz (Orchidaceae) occurs in places in South Finland. Personally, I have noted it since the 1980´s in Lohja and Siuntio (SW Finland). In 2009, a mass occurrence was encountered in Lohja, Jantoniemi: roughly 160 flowering stems, most separate individuals, grew along a little-used road in dryish, pine-dominated woods on fertile rockground.
    As compared with typical E. helleborine, (i) this plant is somewhat smaller and more slender, and with fewer leaves, (ii) the stem, including the inflorescence rachis, is somewhat sinuous, (iii) the leaves are indistinctly distichous, (iv) the leaves are narrower, (v) the leaves are paler in colour, (vi) the inflorescence is less dense, and with fewer flowers, and (vii) the pedicels are slightly longer. In addition, the flowering period may be later on the average, and minor differences may exist in the hairiness of the plant, in the venation of the leaves, in the serrature of leaf margins, and in the flower size.
    The present plant might represent E. helleborine var. minor R.Engel that is currently known from Central Europe. In its vegetative parts, this Finnish morph also has some resemblance to E. muelleri Godfery and E. voethii Robatsch, both likewise taxa of Central Europe. However, the structure of the flowers seems to be roughly the same as that of typical E. helleborine, i.e. that of a cross-pollinator instead of a self-pollinator as in those two. Also two cross-pollinating taxa that have recently been described from Central Europe at least partly share characters with the present morph: E. helleborine ssp. moratoria Riech. & Zirnsack and especially E. guegelii Robatsch.
    I have noticed a faint scent of vanilla in the flowers of both typical Finnish E. helleborine and the present plant.
    Mutant plants of E. helleborine that are totally or partly devoid of chlorophyll occur in some number in a place in SE Finland. These deviating but viable plants are more slender and have fewer flowers and narrower leaves than green plants of the same populations (Salmia, A. 1989: General morphology and anatomy of chlorophyll-free and green forms of Epipactis helleborine (Orchidaceae). – Ann. Bot. Fennici 26: 95-105.). These morphological features of the mutant plants may be due to their diminished vigour or they may represent the present morph.

A photograph of Epipactis aff. guegelii (Photo: Veikko Vuorinen).