considered length intervals were used. After measuring
each single bud length, one anther was excised
from the bud, measured, deposited and crushed over a
microscope glass slide, by applying gently pressure on
the coverslide. Slides were then observed under a
Nikon Eclipse E1000 microscope. In order to determine
the percentages of each microspore/pollen stage
in the same anther, 20 pictures (phase contrast) of ten
different randomly chosen fields were taken at 409.
With an approximate average of 20 microspores/
pollen per picture, around 400 microspores/pollen per
anther were counted and staged. The percentages of
individuals at each stage were calculated by dividing
the number of individuals at a given stage by the total
counted for each anther. The different microspore/
pollen developmental stages were identified according
to the morphological characterization of microsporogenesis
and microgametogenesis described in (Seguı´-
Simarro and Nuez 2005).