Pollen of the Argentinean species of Tropaeolum (Tropaeolaceae)

Abstract

We analyzed pollen morphology of Tropaeolum argentinum, T. atrocapillare, T. capillare, T. incisum, T. meyeri, T. patagonicum, T. pentaphyllum, T. polyphyllum, T. porifolium, T. trialata, T. tuberosum subsp. silvestre, T. warmingianum subesp. warmingianum and T. willinkii to provide supplementary data for the delimitation of these species. Observations, counting and measuring of pollen grains were carried out under optical and scanning electron microscopes. This study points out that Tropaeolum is a stenopalynous genus. Grains are isopolar or isopolar bilateral, radiosymmetric or bisymmetric, small to medium-sized, triangular to subcircular, anguloaperturate, dicolporate, tricolporate or tetracolporate. The exine is tectate, perforate with reticulum supratectate, heterobrochate, angustimurate. Differences among the taxa are discussed, and a palynological key for the Argentinean species of Tropaeolum is presented.