. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 238 ANGIOSPERMAE—DICOTYLEDONES the pollen is shed, and lastly the occurrence of a mass of germinating pollen-grains on the upper surface of the closed stigma. All these facts, in Loew's opinion, lead to the conclusion that the cleft between the anterior stamens is a ' pollinating chamber,' while the ligular tips are ' pseudo-stigmas, or pollen-catchers.' When, for example, a humble-bee of suitable size—Bombus agrorum F., and B. terrester Z., on the Peacock I
. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 238 ANGIOSPERMAE—DICOTYLEDONES the pollen is shed, and lastly the occurrence of a mass of germinating pollen-grains on the upper surface of the closed stigma. All these facts, in Loew's opinion, lead to the conclusion that the cleft between the anterior stamens is a ' pollinating chamber,' while the ligular tips are ' pseudo-stigmas, or pollen-catchers.' When, for example, a humble-bee of suitable size—Bombus agrorum F., and B. terrester Z., on the Peacock Island at Potsdam^flies to the wide opening of the flower, it first alights on the under-lip, the lateral teeth serving as points by which to hold on. It then tries to thrust its head under the sexual apparatus that hangs down from the roof of the flower-entrance, so as to penetrate into the wide sac-like sepal that secretes nectar at its end. When pressing its head against the androecium, it probably pushes forward a little the end of the contained stigma, which is directed obliquely to the front, and with the stigma it moves the pollen-catchers (i. e. the ligules). But even without this assumption, a humble-bee must in many cases, when pressing against the anterior margin of the androecium, introduce its prominent cephalic hairs into the cleft, so as to come into contact with the top of the pistil. When in this way a bee brings pollen from a flower previously visited, this pollen will be retained by the funnel-shaped ligular cap, and will germinate on the stigmatic surface at the top of the ovary. The fact that the stigma of I. Roylei remains closed, the ligular cap obviously occupying its place, lends special probability to this interpretation. Loew also observed a dwarf-flower, intermediate in character between chasmo- gamous and cleistogamous blossoms. Actual cleistogamous flowers, such as have. Please note that these images are extracted from scanned page images that m
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