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 kerneri MENYHARTH 1877. This Rorippa species has been found by MENYHARTH near Kalocsa "in pratis siccis abunde saisis". He recognized it as an independent species (1. c. 39-40). BORBAS (1879a), however, expressed his doubt regarding this specimen. He could not tell whether it was a constant alkaline or marshy species of the Hungarian Lowland (1 c. 4 3a). Later BORBAS collected the same species near Budapest, on the meadow Rákosmező, on swampy ground, in the society of R. silvestris , R. austriaca and R. am phibia , and even together with anomális (fastinatio and chloranthia) (I.e. 64). BORSOS (1951), SOÓ-JÁVORKA (1951) and SOO (1954, 1966, 1968) described this species always as a Rorippa silvestris ssp. kerneri (MENYH. et BORB. 1878) SOO, although MARKGRAF (1960) did not accept the experimental proofs of BORSOS (1951). JONSELL (1964) wrote the following about this plant: "It seems, however, very doubtful whether this species should be. maintained or to be included in R. silvestris BORSOS 1951" (I.e. 205). But in 1968, he was already inclined to consider it probable that it is an ecotype of R silvestris on alkaline ground (I.e. 96) The type-specimen of MENYHARTH (holotype) No. 197, 995, and several isotypes, as well as many specimens collected near Budapest by BORBAS are found in the Herbarium of the Botanical Department. On the seeds of MENYHARTH's type-specimen (Plate IV, 3) it is very well perceptible, that our plant is a new, rather balanced combination of Rorippa austriaca x silvestris x palustris . It may be considered as an independent, hybridogenous species. On the half of the seeds of the R. kerneri specimens, collected by BORBAS near Budapest, the features of the R. amphibia seeds come forward, probably as a result of the interbreeding of the two species occurring together at the same place. In the case of the other seeds the features of R. silvestris and R. palustris prevail, so the seeds are of smaller size. Also the plant itself is taller and stronger than the specimens collected by MENYHARTH (Plate IV, 2). Furthermore, MENYHARTH's dried plant which he named "silvestris formae" agrees entirely with Rorippa hortobágyensis SOÓ (R. kerneri x silvestris) (Plate IV, 4), not only in view of their habit but also in view of their seeds. Both are near to R. silvestris . Studying the Rorippa collection of the Museum, TOMSOVIC determined this species as a hybrid of R. silvestris . The examination of the seeds of PRODAN's type-specimen (1914) (No. 79, 287), i. e, Rorippa küllödensis PROD. (Plate IV, 5) shows that the plant is a hybrid of R. kerneri x amphibia . PRODAN's hybrid, with its mighty structure, thick and hollow stem, the shape of the leaves and with its seeds differs basically from the specimens of R. kerneri .
