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

some specimens also which have come up from seeds; these specimens differed from the mother-plant even in their appearance. The seeds of these latter plants did not show the whole spectrum of the mother-plant. Thus, it may be concluded that even the exterior morphological characters of seeds of such plants are inherent, i. e. hereditary. The phenomena mentioned previously show at the same time the fact that in the case of Rorippa species, which are able to interbreed easily, it is necessary to examine not only the habit of the hybrid plant, or the seeds of several plants of the same type, but also the way of propagation and population of the respective plants. Identification of Rorippa hybrids, on the basis of the external morphological characters of their seeds Rorippa barbaraeoides (TAUSCH 1840 sub. Nasturtio) CELAK 1874. Syn. : Rorippa x astylis (RCHB. 1832 sub Nasturtio) RCHB. 1938/SOÔ 1968. As already mentioned, BORBAS (1878) has determined this hybrid formerly as R. amphibia x silvest

ris and later (BORBAS 1879a) as R. austriaca x silvestris. Even TOMSOVIC when he revised our collection of Rorippas stated that it is a hybrid of R. amphibia x silvestris

. ( TOMSOVIC 1969). According to SOO's synopsis the said Rorippa specimen is a mixture (hybrid) of Rorippa islandica x silvestris

, a stabilized hybrid (SOO 1968). When comparing the seeds of the morphologically identical dried plants in the Herbarium of the Botanical Department, collected at various places at various dates, it can be stated, that these hybrids show without exception rather balanced combinations of the features of seeds of Rorippa amphibia

, Rorippa austriaca and Rorippa silvestris

. Thus, the said Rorippa specimen evolved by a triple hybridization, and since it has hecome independent and constant, it may be considered as a hybridogenous species. The seeds of Rorippa barbaraeoides have some morphological features of R. amphibia, R. austriaca and R. silvestris respectively: namely: greater shize, caracteristics of hylum of R. amphibia

; as well as the shape and the granulate surface of hylum region, the side walls of the sclerotic layer cells of the R. austriaca seeds which walls are especially well visible under greater magnification, sticking out like thorn and forming an acute angle meeting each other; the shape and hylum region and their darker marginal stripe of R. silvestris seeds. On the seed picture of this species not one of characteristic features of R. islandica (resp. palustris) is found. For illustration purposes, I wish to give three seed pictures of Rorippa barbaraeoides TAUSCH (Plate II, 6-7) in two enlargements. And for comparative purposes in order to easily discern the features enumerated above I enclose the seed pictures of three other stabilized hybridogenous spe-