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Darwin, Charles, 1809-1882

"The Different Forms of Flowers on Plants of the Same Species"


As the pollen-grains of ordinary species belonging to the same genus generally
resemble one another closely in all respects, it is worth while to show, in
Table 6.34, the difference in diameter between the grains from the two or three
forms of the same heterostyled species in the forty-three cases in which this
was ascertained. But it should be observed that some of the following
measurements are only approximately accurate, as only a few grains were
measured. In several cases, also, the grains had been dried and were then soaked
in water. Whenever they were of an elongated shape their longer diameters were
measured. The grains from the short-styled plants are invariably larger than
those from the long-styled, whenever there is any difference between them. The
diameter of the former is represented in the table by the number 100.
TABLE 6.34. Relative diameter of the pollen-grains from the forms of the same
heterostyled species; those from the short-styled form being represented by 100.
DIMORPHIC SPECIES.
Column 1: Name of species.
Column 2: From the long-styled form : relative diameter.
Primula veris : 67.
Primula vulgaris : 71.
Primula Sinensis (Hildebrand) : 57.
Primula auricula : 71.
Hottonia palustris (H. Muller) : 61.
Hottonia palustris (self) : 64.
Linum grandiflorum : 100.


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