False colour scanning electron micrograph of many pollen grains of a Colts foot,Tussilago farfara. Its outer wall (exine) consists of sharp spines; these get caught in an insects fur and are thus transferred when the insect goes to a different flower to feed. There are also germinal pores each capped with an operculum (lid). When the pollen grain,containing the male gametes,lands on the stigma of the flower,it germinates. A pollen tube grows out from one of these pores,down through the stigma,to the ovary. The male nuclei pass down the tube,fertilize the ovules & a seed is formed. Magnification: X236 at 35mm size | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Litchfield, R.E. |
Bildgröße: | 2643 px × 3675 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |