Three groups of species in Petunia sensu Jussieu (Solanaceae) inferred from the intact seed morphology

The intact seed surface morphology in 45 taxa of Petunia sensu Jussieu nati ve to South America (Petunia sensu Wijsmann plus Calibrachoa) was compared under scanning electron microscopy. The existence of three groups of specie s. differentiated in terms of seed morphology. was revealed as follows: (1) all species of Petunia sensu Wijsman, having coarse wavy middle lamellae a nd anticlinal walls: (2) Calibrachoa parviflora and C. pygmaea, having fine wavy middle lamellae embedded in straight anticlinal walls; and (3) the ot her species of Calibrachoa, having straight middle lamellae and anticlinal walls. Close relationships between seed morphology and the other characteri stics observable in the groups of species are discussed.