Fruit micromorphology and morphometry of eight wild-growing roses in Serbia

This study investigates the micromorphology and morphometrics of aggregate fruit (ripe hypanthium and achene) of eight wild Rosa species collected throughout Serbia. Field research was conducted to find roses at different habitats, collecting 1,836 aggregate fruits with 25,999 achenes from 137 shrubs. Multicellular glandular trichomes are found on the hypanthium surface, while long and short stalk capitate glandular trichomes were observed on the fruits of R. gallica, R. pendulina, R. tomentosa and R. villosa. Numerous unicellular non-glandular trichomes were found inside the urceolate hypanthium and on the surface of most studied achenes, except for R. spinosissima species. Micromorphological analysis revealed three types of exocarp ornamentation: scalariform (R. dumetorum, R. tomentosa and R. micrantha), reticulate (R. gallica, R. arvensis, R. spinosissima and R. villosa) and reticulate-smooth (R. pendulina). Morphometric analysis indicated significant differences among the 14 morphological characters. Achene length was the most significant morphometric feature for identifying Rosa species (P˂0.05). The results contribute to our poor knowledge of rose fruit morphology and provide some well-defined microcharacters that could be used as additional features for species delimitation.