Polygonum pollen. Coloured Scanning Electron Micrograph (SEM) of a pollen grain of the Knotweed Polygonum sp. The pollen grain is spherical. It has a highly sculptured outer wall (exine) of tiny columns (bacula),some fused at their tips to form ridges or walls (muri) arranged in a network. The ridges enclose irregular shaped areas studded with granular wart-like processes. The pollen grain,containing the male gametes,is dispersed,lands on the stigma of the flower and germinates. A tube grows out of the pollen grain,passes through the stigma and reaches the ovary. The male nuclei pass down the tube,fertilize the ovules and seeds are formed. Magnification: x1100 at 6x7 cm size. x1,750 at 4x5ins | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Scharf, David |
Bildgröße: | 5120 px × 3692 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: |
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