Zs. P. Komáromy szerk.: Studia Botanica Hungarica 12. 1977 (Budapest, 1977)

Radics, Ferenc: The identification of Rorippa species and hybrids (Cruciferae) based on external morphological features of their seeds

SUMMARY AND CONCLUSIONS My examinations involved only the basic Rorippa species and some most contestable Rorippa hybrids first of all with a view to the external morphological features of their seeds. The statements and results regarding the seeds and the nature of plants were controlled by the study of the plants habit. Neither the varieties nor the forms were taken into account, although with a view of some supplementary data it may be supposed that, in some way, the hybridization took part in their formation too. Among the Six basic species of the Rorippa genus the seeds of the autogamous Rorippa palustris are almost identical whilst those of the other species probably owing to their allogamous reproduction and frequently secondary occurrence, somewhat differ from each other. On the other hand, on basis of the seeds, also the fact can be stated that within this genus, in addition to the so-called hybridogenous, stabilized species, there are further unbalanced hybrids. These are not yet stabilized, thus propagate constantly their race in a vegetative way only. If they occur alone, they may separate and create the so-called "swarm of hybrids" in the generative way, just as the primary hybrids or by introgressive re-crossing. The Rorippa hybrids I examined first of all on basis of their seed pictures, proved to be double or triple hybrids. The single specimen of Nasturtium subarmoracioides (N. barbaraeoides x armoracioides) CSATO et SIMK. was examined as control. According to other authors (BORBAS, JAVORKA, TOMSOVIC, FRÖHLICH etc). I think that the following hybrids are double, stabilized hybrids, thus, independent hybridogenous species: Rorippa repens BORB. (R. amphibia x silvestris), Rorippa hungarica BORB. (R. amphibia x austriaca), Rorippa terrestris TAUSCH (R. silvestris x austriaca) and Rorippa erythrocaulis BORB. (R. amphibia x palustris). The following ones are equally hybridogenous, stabilized species, but with a view to their composition, or more correctly, to their origin, they are not double hybrids but in opposition to earlier statements, triple hybrids: Rorippa barbaraeoides TAUSCH (R. amphibia x silvestris x austriaca), Rorippa armoracioides TAUSCH (R. silvestris x austriaca x palustris), and Rorippa k'erneri (R. austriaca x silvestris x palustris). Thus this latter plant is not a subspecies of Rorippa silvestris (L. ) BESS, but it is an independent hybridogenous species. This is proved also by the fact that it can be crossed with R. amphibia (Rorippa küllődensis PROD, or with R. silvestris) (R. hortobágyensis SOO). The forms of Rorippa kerneri MENYH. collected by BORBAS seem to be a primary crossing namely with Rorippa amphibia. It can be concluded that any analysis of the population, any horticultural or crossing experiment, any cytological examination of Rorippa specimens has to be preceded, in addition to the diagnosis of their habit, also by an analysis of the external morphological features of their seeds. JONSELL