Specific features of ontogeny in some tuberous-rooted orchids (Orchidaceae) in the Extreme North.

摘要

It is very difficult to distinguish ontogenetical stages in orchids, especially those with tuberous-rooted life forms. This is connected primarily with the widespread necrosis of the old parts of plants and, therefore, with the lack of morphologicalstructures required for the assessment of plant age. All biological information about definite ontogenetical stages may be taken from measurements of the last-order shoot. In the Far North of Russia, it is difficult to distinguish different ontogenetical stages of tuberous-rooted orchids because of metamere reduction, unthickened adventitious roots and small total size of the plant. The basic criteria for distinguishing the age of the species studied in 1992-94, viz. Dactylorhiza maculata, Coeloglossumviride, Gymnadenia conopsea and Platanthera bifolia, were the numbers of leaf ribs, unthickened adventitious roots and tuberous-root lobes. The post-seed initial stages of development recorded in the populations studied were: protocorm - "seedling" - juvenile plant. According to habitat, two kinds of "seedling" were found, underground and above-ground. Apart from these stages, the age spectrum was represented by immature, vegetative and reproductive individuals.