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

Rorippa proliféra HEUFF. (Plate II, 1-2) Length: 0. 3 to 0. 4 mm. Shape: juglike, beneath hilum somewhat inclined, provided with neck. Near hilum rounded, opposite to hilum: pointed. Sclerotic layer netlike covered with small dimples, but meshes (colliculate bays of network) here being the smallest: (10 to 15 urn). Exterior walls of epidermis cells wrinkled even when wet. Colour: brown. Radicle: appearing to be spirolobal. Rorippa pyrenaica (LAM. ) RCHB. (Plate II, 5) Length: 0. 6 to 0. 7 mm. Shape: oval. Near hilum, beak-shaped and thin, obtuse, opposite to hilum obtusely pointed. Pattern of sclerotic layer: roughly (more thickly than in other species) reticulated with dimples. Lower wall of cells of this layer dotted. Epidermis layer transparent. Colour: reddish brown. Radicle: frequently obliquely accumbent to cotyledons. Rorippa silvestris (L. ) BESS. (Plate II, 3-4) Length: 0. 6 to 0. 7 mm. Shape: oval. Near to' hilum blunt, opposite to hilum slightly cut off. Sclerotic layer: netlike with dimples and it is perceptible well owing to the transparent epidermis cells. Horizontal extension of meshes (bays) agreeing basically with that of R. amphibia. Colour: brown, but margin of seeds is bordered with a darker, reddish brown band. Radicle: accumbent. The morphological features of the six Rorippa species also appear on their hybrids, thus they are hereditary, namely: purely, combined or seldom mosaic-like. Of course, when trying to state the morphological features of Rorippa-seeds, also the immediate influence of some foreign pollenizing father-plant (metaxeny) should be taken into consideration. This phenomenon has been observed by FEDOSSEJEWA (1936) also among other Cruciferae (I.e. 79). But the plants examined by me differ from the other Rorippa specimens in the same way, not only as far as their seeds are concerned but also with a view to their habit. Moreover, the identical morphological features of these seeds appear on Rorippa specimens originating from different places and from different years. Especially convincing arguments are some morphological features of hybrid seeds if the parents do not occur at that place at all. Furthermore, the seed pictures of the stabilized hybrids already present sufficiently balanced combinations of species, just as their external appearance. I examined also a polymorph, unbalanced, so-called transitional Rorippa-hybrid with unaltered habit. Such a habit has been saved only by vegetative propagation (by shoots) But these plants had