. Handbook of flower pollination : based upon Hermann MuÌller's work 'The fertilisation of flowers by insects' . Fertilization of plants. Fig. 241. Primula vulgaris, Huds. (1) and (2) Short- anj long-styled flowers, in longitudinal section (X 2). 3 0 4 0 Relative size of the pollen-grains (3) of the short-styled, and (4) of the long-styled (lower. Relative size of the stigmatic papillae (5) of the long-styled, and (6) of the short-styled flower. darker nectar-guide at the base of each corolla-lobe. Their diameter varied from al- to 4 cm., but was usually about 3 cm. Similarly the length of the
. Handbook of flower pollination : based upon Hermann MuÌller's work 'The fertilisation of flowers by insects' . Fertilization of plants. Fig. 241. Primula vulgaris, Huds. (1) and (2) Short- anj long-styled flowers, in longitudinal section (X 2). 3 0 4 0 Relative size of the pollen-grains (3) of the short-styled, and (4) of the long-styled (lower. Relative size of the stigmatic papillae (5) of the long-styled, and (6) of the short-styled flower. darker nectar-guide at the base of each corolla-lobe. Their diameter varied from al- to 4 cm., but was usually about 3 cm. Similarly the length of the corolla-tube was i|-2§ cm., mostly, however, about 2 cm. In the long-styled form the stigma is situated in the opening of the flower, while the anthers are inserted into the corolla-tube about its middle. In the short-styled form the opening of the corolla-tube, which widens somewhat like a funnel, is, of course, occupied by the five anthers, while the style with its stigma is about half as long as the tube. There are microscopic differences between the two forms as regards the length of the anthers and the shape of the stigma. In short-styled flowers the anthers are generally rather more than 2 mm. long, in long-styled ones usually a little less. The stigma in the latter is spheroidal as a rule with a diameter of i-i mm., but in short-styled flowers it is mosdy somewhat flattened, about 1-2 mm. broad and 0^9 mm. deep. With the aid of a lens the stigmatic papillae of the long-styled form are clearly visible, but those of the short-styled one scarcely perceptible. The former are 0-07 mm. long and o-oi mm. broad, the latter 0-02 mm. long and about the same in breadth. The pollen-grains are of an angular ovoid shape, those of the long-styled form 0-025 '^'^â long and 0-02 mm. broad, and those of the short-styled one almost 0-04 mm. long and 0-025 mm. broad. As in the case of the last species, Ljungstrom observed four varieties in the island of Moen, i. e. brevicalyx, longica
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