Jordano, P. 1990. Reproductive biology of three species of genus Lonicera (Caprifoliaceae) in the Sierra de Cazorla. Anales Jard. Bot. Madrid 48(1): 31-52. (in Spanish).
The first data on flower biology and breeding systems of three species of honeysuckle (Lonicera arborea Boiss., L. etrusca G. Santi and L. splendida Boiss.) are reported for populations in the Sierra de Cazorla y Segura (Jaén province, Spain). L. arborea is predominantly pollinated during the day by bumblebees (Bombus spp., Xylocopa spp. and Psithyrus vestalis, 70.1 % of visits) and honeybees (28.3 % of the visits recorded), while L. etrusca and L. splendida are pollinated during the evening and night by sphingid moths (76.7 and 60.4% of visits, respectively). Bees are nectar robbers in these two species with long tubular corollas. Percentage of flowers damaged by nectar thieves averaged, per plant, 34.2% [10.1-75.6] for L. etrusca and 18.2% [3.6-48.8%] for L. splendida. Flowers of L. arborea last 4 days, with the stigma being receptive during the first and second day; anthers dehisce on the second day of anthesis. Nectar production in this species peaks in the second and third days. Flowers of both L. etrusca and L. splendida open approximately 1 h before dusk; the stigma is receptive an the first and second nights and anther dehiscence occurs on the second day. Maximum nectar secretion for both species was recorded during the first night of anthesis. Nectar secretion by L. arborea amounts to 1.7 µl per flower/day with 40.2% disaccharide sugar concentration while the other two species secrete 2.8 and 4.6 µl with concentration of 23.5 and 19.6%, respectively. Seed set increased significantly after crossed (xenogamous) pallinations (57-95% of flowers) relative to geitonagamous crossings (18-29%) or controls. L. arborea was the only species setting fruits with pollinators excluded. Xenogamous pollinations resulted in greater weights of fruits and seeds for L. etrusca and L. splendida because of the increased number of seed set but not as a result of the treatment itself. Xenogamaus crossings resulted in significant increases in number of seeds per fruit for the three species. Results suggest a dichotomy of pollination systems within the genus among the sections Caprifolium (long-tubed corollas) and Lonicera (short-tubed carallas), strongly associated with other differences in growth patterns, geographic distribution and habitat occupancy.