Swede seed germinating (Brassica napus)Ref: 80018739
Germinating seed. Coloured scanning electron micrograph (SEM) of the main stages in the germination of a plant seed. The sequence runs from left to right. The first two images show the emergence of the radicle (white), the embryonic root, from the seed coat (testa, brown). In the third image, the root grows downwards in response to gravity (geotropism), while in the fourth image the embryonic shoot (plumule) grows up against gravity. Its seed leaves (cotyledons, green) will photosynthesise using sunlight. The root 'hairs' will help obtain water and nutrients. This is a swede (Brassica napus) seedling.