RUNNING HEAD
15
BEES AND BOTTLEBRUSH MICHAEL KIRBY Bottlebrush bushes (Callistemon citrinus and C. rigidus) in my garden flowered profusely in the last week of June and July during a spell of warm settled weather. Within a day of the first flowers unfolding they were visited by honey bees and bumble bees (Bombus lucorum and B. lapidarius) which continued to work the flowers during the whole of the flowering period. There were 100–150 inflorescences per bush and at any one time there were one or two honey bees per inflorescence; bumble bees were fewer in number, about 10–15 per bush and common wasps (Vespa vulgaris) and hoverflies were also regular visitors. (The visits by the wasps were puzzling. None was caught to find out if they were new queens or workers freed from the task of feeding larvae.) The inflorescence of bottlebrush is about 180 mm long and consists of about 80 closely packed flowers forming a tight spiral round the axis (Plate 7). Each flower has five small sepals and five petals around the rim of a deep calyx tube; each petal subtends six 15–20 mm long stiff stamens each with a small, versatile anther. The ovary is situated at the base of the cup formed by the calyx tube with a long stiff style forming, with the stamens, a dense, strong ‘thicket’. The nectary at base of each cup produces copious nectar, easily seen glistening in the sun. (Fig. 1)
Figure.1. Longitudinal section of a bottlebrush flower to show the calyx tube and ovary. Copious nectar accumulates around the ovary. Honey bees quickly discovered the flowers and at first seemed uncertain how to get at the nectar. They approached the flowers from the base or top of the inflorescence, standing on the leaves or the exposed petals before probing for nectar (Plate 8). Soon, however, they developed a technique of landing in
Trans. Suffolk Nat. Soc. 45 (2009)