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OBSERVATIONS ON THE FLORAL BIOLOGY OF DIGITALIS SPECIES
Author(s) -
PERCIVAL MARY,
MORGAN PATRICIA
Publication year - 1965
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1965.tb05370.x
Subject(s) - nectar , biology , pollen , botany , pollination , digitalis , pollinator , stamen , insect , horticulture , medicine , heart failure
S ummary Observations were made on the floral biology of Digitalis amandiana, D. ambigua, D. lanata, D. lutea and D. purpurea . The rhythms of flowering, pollen presentation, stigma opening and nectar secretion were investigated and the amount and concentration of the nectar measured. The flower sizes and insect sizes were compared, and proved that Bombus lucorum workers and queens, and B. agrorum workers and queens, were unable to reach the bottom of the corolla tube of Digitalis lutea. Bombus lucorum chiefly chose this species as nectar seeped along the lower side of the corolla to heights which it could reach (see addendum). The other species had no mechanical barrier to full exploitation of the nectar by B. lucorum and B. agrorum. B. agrorum preferentially worked Digitalis ambigua in early summer and D. lanata later. This paper describes observations made over two seasons, in both natural and glasshouse conditions. The full significance of much of the data cannot yet be evaluated but a tentative assessment of the significance of bee visits for pollination and hybridization is given.