H. Muller in his
interesting description of several other species shows that P. bistorta is so
strongly proterandrous (the anthers generally falling off before the stigmas are
mature) that the flowers must be cross-fertilised by the many insects which
visit them. Other species bear much less conspicuous flowers which secrete
little or no nectar, and consequently are rarely visited by insects; these are
adapted for self-fertilisation, though still capable of cross-fertilisation.
According to Delpino, the Polygonaceae are generally fertilised by the wind,
instead of by insects as in the present genus.
[Leucosmia Burnettiana (Thymeliae).
As Professor Asa Gray has expressed his belief that this species and L.
acuminata, as well as some species in the allied genus Drymispermum, are
dimorphic or heterostyled (3/15. 'American Journal of Science' 1865 page 101 and
Seemann's 'Journal of Botany' volume 3 1865 page 305.), I procured from Kew,
through the kindness of Dr. Hooker, two dried flowers of the former species, an
inhabitant of the Friendly Islands in the Pacific. The pistil of the long-styled
form is to that of the short-styled as 100 to 86 in length; the stigma projects
just above the throat of the corolla, and is surrounded by five anthers, the
tips of which reach up almost to its base; and lower down, within the tubular
corolla, five other and rather smaller anthers are seated.
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