Pollen studies
Both the pollen size and stainability were tested in 25 populations of different species (Table 9). In C. zeylanicum, there is no clear correlation between the pollen size and the chromosome
numbers 2n= 22 and 2n= 30. For example, the population 21 has the largest pollen grains (mean
value 108 pm) despite its chromosome number being 2n= 22. Thus, the populations with 2n= 30
(24-27) can not be distinguished in pollen size from those with 2n=22 (210-214). The two
triploid populations examined (28 and 215) show, as expected, a wide variety in pollen size and the pollen grains are slightly larger than in the diploids. In C. macowanii there is some correlation between the pollen size and ploidy levels. The tetraploids (M4 and M5) have larger pollen grains than the diploids (MI-M3). The examined populations of C. jagus (Jl-J3), C. glaucum ( G 2 4 3 ) ,C. purpurascens (PI) and C. natans (N I ) showed similarities in both mean pollen size and in stainability. An exception is C. purpurascens
(P2) in which the number of unstained pollen grains is surprisingly large, as meiosis seems
quite regular.