. Handbook of flower pollination : based upon Hermann MuÌller's work 'The fertilisation of flowers by insects' . Fertilization of plants. CRASSULACEAE 423 the Riesengebirge, according to Schulz, and in the male and female flowers there are vestiges of the other sex-organs. Axell also found only dioecious plants, as did Lindman on the Dovrefjeld. Ricca, in the Alps, observed protandrous herma- phrodite flowers, and so did Warming in Greenland, but the latter noticed also cases of trioecisni. Ekstam says that in Nova Zemlia the flowers smell like honey, and secrete abundant nectar. Visitors.âSma
. Handbook of flower pollination : based upon Hermann MuÌller's work 'The fertilisation of flowers by insects' . Fertilization of plants. CRASSULACEAE 423 the Riesengebirge, according to Schulz, and in the male and female flowers there are vestiges of the other sex-organs. Axell also found only dioecious plants, as did Lindman on the Dovrefjeld. Ricca, in the Alps, observed protandrous herma- phrodite flowers, and so did Warming in Greenland, but the latter noticed also cases of trioecisni. Ekstam says that in Nova Zemlia the flowers smell like honey, and secrete abundant nectar. Visitors.âSmall flies were noticed by Ekstam in Nova Zemlia. Ricca observed flies and ants in the Alps. In Dumfriesshire, an Empid and a Muscid were recorded (Scott-Elliot, ' Flora of Dumfriesshire,' p. 68). 281. Sedum L. Flowers protogynous, or homogamous to markedly protandrous; with half- concealed nectar, secreted basally between petals and stamens. 995. S. acre L. (Herm. Miiller, 'Fertilisation,' pp. 251-3; MacLeod, Bot. Jaarb. Dodonaea, Ghent, vi, 1894, p. 289 ; Knuth, 'Bl. u. Insekt. a. d. nordfr. Ins.,' pp. 74, 154, ' Weit. Beob. u. Bl. u. Insekt. a. d. nordfr. Ins.,' p. 234.)âThe flowers of this species are bright yellow in colour, and the five outer stamens super- posed to the sepals are the first to mature. They direct their filaments (about 5 mm. long) obliquely up- wards. When they have shed their pollen they bend back towards the petals, while the five inner anthers dehisce, and assume the position of the first five. The small terminal stigmas of the five carpels do not mature till the inner anthers have shed all their pollen. I observed this marked piotandry, which completely prevents self-pollination, in the island of Fohr. Elsewhere the flowers are not so distinctly protandrous. Hermann Miiller states that in Westphalia the stigmas mature before the five inner stamens have finished shedding their pollen, so that automatic self-pollination is possible if insect- visits fa
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