Note on the intraspecific variation of style shape, a trait of potential taxonomic value, in pea (Pisum sativum)

The traditional systematics of the leguminous tribe Fabeae, including numerous important temperate crops and their wild relatives, was based on morphological features among which style shape was considered as one of the most important. Using scanning electron microscopy, we describe a phenotypic variation of the style shape in a garden pea (Pisum sativum) strongly reminiscent of the one of its allied genus, Vavilovia. The two morphs differ in the mode of the junction between the style and the ovary. Typically, the style margins continue on the carpel valves as ribs in pea, whereas in a newly discovered form and Vavilovia the ovary is free from the style margins. These differences probably have little or no impact on breeding value and adaptive potential and hence were hardly selectable in the course of crop diversification and natural evolution. The existence of intraspecific variation resembling interspecific differences contributes to the idea that minor morphological nuances are of relatively low value in the systematics of related genera and species.