engleski

Morphological variability of leavs of Reynoutria japonica Houtt. and Reynoutria x bohemica Chrtek et Chrtkova from the City of Zagreb, Croatia

Reynoutria species (=knotweeds) are classified amongst worst invasive plants in Europe. Three taxa of Reynoutria occur in Croatia: R. japonica Houtt., R. sachalinenis (F. S. Petrop.) Nakai in T. Mori and R. × bohemica Chrtek et Chrtková, the latter being a hybrid between the two former ones. Because of its great resemblance to the parental species, botanists have been mistakenly referring to hybrid specimens as parental taxa for decades. It is believed that, in comparison with the parents, the hybrid is more difficult to control, while in the same time, the hybrid is the most widespread knotweed in Croatia. Here, we have measured the leaf traits (largest width, length from the apex to the largest width, total length, leaf area, length of the heart-shaped part) from main and secondary axis of R. japonica and R. × bohemica, using leaves from 10 localities per taxon, and analysed them using descriptive statistics and ANOVA. All measured traits showed higher values in hybrid populations (e.g. mean largest width: 13.42 vs. 10.23 cm ; mean total length: 15.8 vs. 11.34 cm ; mean leaf area: 171.74 cm2 vs. 87.54 cm2, all measures from main axis leaves). Because of their greater morphological variability, leaves from secondary axis are less reliable in the determination of taxa. The shape of the leaf base, in most cases more or less heart-shaped in hybrid populations, is a good indicator of the hybridogenous origin.

comparison, identification, knotweeds, morphology

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