334 THE FERTILISATION OF FLOWERS. [PART In. 
female florets. At night and in dull weather the capitulum closes up, 
but in sunshine it expands to a golden-yellow disk 20 to 25 mm. in 
diameter. The central florets have an ovary with an abortive ovule ; 
around the base of the style is a yellow, fleshy nectary, which is 
visible through the base of the white tube of the corolla, which is 
4mm. long. The honey rises into the dark-yellow, conical throat, 
which is more than 1 mm. long; from this throat the anther- 
cylinder protrudes. The branches of the style remain hea 
almost to the tip, and are covered above and on their outer eee 3 
with short sweeping-hairs. The marginal florets have a perfect C 
ovule, a tube 3 mm. long, devoid of honey, and a narrow linez 
outer lobe 6 to 8 mm. long. The style projects 2 to 3 mm. beyon F 
the tube of the corolla, and divides into two branches not half a 
millimetre long, furnished on their inner surfaces with stigmatic 
papillae and on their outer surfaces and at their tips with 
sweeping-hairs which are no longer of use to them. Thus division 
of labour has here taken place: the marginal florets make the 
capitulum conspicuous and produce seed, while the central florets 
secrete honey and produce pollen. The stigmas in the marginal 
florets are distinctly developed before the pollen emerges at the 
top of the anther-cylinder ; so that if sufficient insect-visits occur, . 
cross-fertilisation of separate capitula always takes place. In 
absence of insects self-fertilisation is obviously impossible. 
‘Visitors (April 11, 1869, Stromberg Hill): A. Hymenoptera—A pide: 
(1) Apis mellifica, L. §, in hundreds, s, and c.p.; (2) Andrena fulvicrus, 
K. 2, do.; (3) A. Gwynana, K. 9, s. and e.p., freq.; (4) A. parvula, K. 
2, do.; (5) Halictus nitidus, Schenck, 2?,¢p. B. Diptera—(a) Bombylide 
(6) Bombylius major, L., s.; (b) Syrphide: (7) Eristalis tenax, L., fp. U 
Coleoptera—Nitidulide : (8) Meligethes, f.p., freq. A list of Alpine visitor: 
(twenty-one flies, three bees, one ant, two Lepidoptera) is given in m 
Alpenblumen (609). ; 
Petasites albus, Girtn., is dicecious, and, as is usual in dicecious 
plants, the male capitula are the more conspicuous. In the femal 
capitula there are two kinds of florets. In the centre are some whose — 
only function is to produce honey, but which possess functionless — 
stamens and pistil ; and around these stand a much larger number 
of female florets, which produce no honey and possess no stame ns 
The male capitula may consist of florets of one kind only; thes 
secrete honey and possess a style, whose branches sweep out the 
pollen from the anther-cylinder by means of hairs in the ordinar 
way but are not provided with stigmatic papille. But the male 
capitula, as often as not, contain some small fwnetionless florets 
