Figure 1.
Developing phases of Hibiscus rosa-sinensis flower.
A: immature stage, pollen is forming and reproductive organs of the flower are not observed, 1–3 days. B: bud stage, the flower enters in pre-anthesis, 4–5 days. C: anthesis stage, 5–8 days. D: final phase of anthesis, pollen remains viable, 9–12 days. E: senescence phase, flower begins to close, 13–15 days. F: the flower separates from the tree.
Figure 2.
A: young stage, pollen grains maintain connections with the anther and the spines are not yet well defined, although they begin to distribute symmetrically over the pollen grains surface. B: adult stage, the pollen has a spherical shape with sharp and long spines. C: old stage, the grain begins to deform, it becomes more vulnerable to treatment for SEM. We identify also that the exine in old stage begins to separate from the surface of pollen, as clearly seen in the picture.
Figure 3.
Comparison between an Hibiscus rosa-sinensis grain pollen (A) and a buckminster C60-fullerene molecule (B) (Creative Common License – Rob Hooft).
As seen, both structures present a defined distribution of their elements over the whole surface forming hexagons and pentagons.
Figure 4.
Graphical relationship between a hexagon and a pentagon that share an edge.
From this it is possible to calculate what should be the distance between their respective center and vertices (i.e. O1Q, O1A, O2P, O2E,…) and the magnitude of their respective apothems O1H and O2H.
Figure 5.
Euclid’s construction showing the length of the corresponding icosahedron inscribed inside the sphere.
To the right is a sketch of the main lines that form the top and bottom of the icosahedron.
Figure 6.
Planes that cut icosahedron edges are perpendicular to the radii subtended to their respective vertices.
The edge of the icosahedron is then cut into three segments, the middle one PR is the length edge of the truncated icosahedron or fullerene molecule.
Figure 7.
Microphotography of a pollen grain showing angle measurement of some of the spines on its surface.
Table 1.
Comparison of Spine index and D-spine-index in the three stages of pollen showing the variation as the grain reaches the end of its life span.