Floral syndrome and breeding system of the spring flowering plant Iris scariosa (Iridaceae)

Abstract

Iris scariosa is a perennial spring flowering Iridaceae species with important ornamental value. To explore the floral syndrome and breeding system and promote the utilization of this germplasm, flowering phenology, floral syndrome, breeding system and pollination traits of this species were studied in field and controlled experiments. The results were as follows: (1) I. scariosa began to flowering in early-May, peak flowering period was at mid-May, and final flowering period was at late-May, the duration of flowering was 16 d. (2) Its blue-purple flowers had scent and a small amount of nectar, and individual flower duration was 2.5-3.0 d. (3) Results of pollination experiments suggested that the breeding system of I. scariosa is obligate xenogamy, without apomixes and the ability of spontaneous self-pollination. (4) I. scariosa has a generalist pollination system, with Apis mellifera, A. cerana and Halictus sp. being pollinators. These insects initiated pollination while foraging for pollen, and their visitation frequencies were (0.57±0.05), (0.42±0.04) and (0.19±0.03) times·flower-1·h-1, respectively. Floral traits of this species, such as bright flower colors, large flower display, the peak of insect visitation overlapping with the period of highest pollen viability and the optimal stigma receptivity of pollen, yellow beard appendage on the outer tepals, etc., ensure the completion of the pollination process and enhance the successful outcrossing. This study provides an important theoretical information for the resource utilization and germplasm innovation of I. scariosa.

Keywords

• iris scariosa
• spring-flowering plant
• floral syndrome
• breeding system
• outcrossing