Taxonomic Treatment of Chimeras in Orchids

Leaf variegation is a well-known illustration of chimerism in plants, resulting from heterogeneity of genetic material within the shoot apical meristems. The occurrence and manifestation of chimeras in the family Orchidaceae is poorly understood. There-fore, the aims of the present study were to analyze the chimeric phenotype of variegated leaves in wild European orchids and to discuss the taxonomic rank of chimeras. We document the presence of periclinal-mericlinal chimeras in Epipactis purpurata and Cephalanthera damasonium, and discuss the variegated phenotypes in the context of the shoot apical meristem activity. Descriptions of chimeric orchids refer mostly to cultivars and only rarely to wild plants, in which the taxonomic rank of chimeras is uncertain, and not discussed in the literature. Lack of precise rules in the International Code of Nomenclature for algae, fungi and plants results in randomness in chimera categorization and taxonomy. In this article, using orchids as our case study, we discuss the problem of chimeras' taxonomic status. Orchid cultivars and in particular their nomenclature are neither studied nor discussed here.