Pollen limitation in three sympatric species of Vaccinium (Ericaceae) in the Upper Ardennes, Belgium

• Published in: Plant systematics and evolution Vol. 207; no. 3/4; pp. 159 - 172
• Main Author: Jacquemart, A.-L.
• Format: Journal Article
• Language: English
• Published: Springer-Verlag 01-01-1997
• Subjects: Flowers; Fruit set; Fruits; Plants; Pollen; Pollination; Seed production; Seed set; Seeds; Sympatric species
• ISSN: 0378-2697; 1615-6110
• DOI: 10.1007/BF00984387

The reproductive success of three co-flowering species of Vaccinium (V. myrtillus, V. vitis-idaea and V. uliginosum) was studied in one heathland of the Upper Ardennes, Belgium, during three years (1988—1990). The purpose was to examine whether pollen limitation, flower position and flowering phenology may influence patterns of fruit set in these three sympatric species. I quantified fruit and seed set following supplementary hand-pollinations and compared this to natural fruit set. On the same plants, I also quantified fruit and seed set in relation to the spatial position of the flowers on the ramet and their temporal sequence of blooming. Hand-pollination had no significant effect on fruit set in V. vitis-idaea and V. uliginosum, but significantly increased seed number per fruit in 1989. In V. myrtillus both fruit and seed set were increased by supplementary pollination, but significantly in only one year. Analyses of position effects revealed that the fruits in the lower positions in the ramet did not mature preferentially and did not contain more seeds in V. uliginosum and in V. vitis-idaea. Flowering phenology also had no significant effect for these species. In V. myrtillus hand-pollinated flowers showed a seasonal decline in seed number, and control (naturally pollinated) flowers showed a seasonal increase in fruit set. Fruit and seed set appear to be pollen-limited rather than resource-limited in V. uliginosum. In the two other species, unfavorable weather (frosts) could be a more important cause of low fruit and seed set.