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Development Home Germination Early growth and tillering Stem elongation Wheat apex development Flowering and fertilisation Pollen release Grain growth 1 to 4 days Grain growth 4 to 10 days Cell layers inside a grain Grain filling 11 to 16 days Whole grain photographs Endosperm micrographs Embryo sac: wall changes Embryo micrographs
Grain filling 17 to 21 days Grain filling 21 to 30 days Development of the embryo Dry down 30 to 40 days How we grew the plants Photography and microscopy
DAYS = days after flowering
Development Home Germination Early growth and tillering Stem elongation Wheat apex development Flowering and fertilisation Pollen release Grain growth 1 to 4 days Grain growth 4 to 10 days Cell layers inside a grain Grain filling 11 to 16 days Whole grain photographs Endosperm micrographs Embryo sac: wall changes Embryo micrographs
Grain filling 17 to 21 days Grain filling 21 to 30 days Development of the embryo Dry down 30 to 40 days How we grew the plants Photography and microscopy
DAYS = days after flowering
Grain filling 11 to 16 days
Embryo micrographs
 | 16 days after flowering the scutellum is well developed and is using starch reserves nearby to support its growth. The endosperm cells from which the starch has been taken will become the 'crushed cell layer'. |
 | The above image in polarized light shows the pattern of starch accumulation. Starch patterning in this area of the endosperm is constantly changing as the embryo uses these reserves for its own development. |
 | The embryo is developing rapidly and at 11 days after flowering has an elongated shape. Its position on the dorsal side of the grain was established early on. Compare its size here with the embryo at 15 days after flowering. Densely cytoplasmic cellular endosperm is still present at 11 days after flowering. The embryo has been supported by these reserves up to now. |
 | The image above in Darkfield illumination shows where starch is present. There are minimal starch deposits in the endosperm at 11 days after flowering but the maternal tissues surrounding the embryo sac still contain starch. |
 | The image above in Darkfield illumination shows the changing pattern of starch distribution. There is more starch present in the endosperm here than at 11 days after flowering. |
 | 15 days after flowering. Within the past four days the scutellum has differentiated and the two embryonic poles are now recognizable as shoot and root. The scutellum is the organ that will transfer nutrients from the endosperm to the embryo both now, during grain filling, and later when the seed germinates and the growth cycle starts again. It is the large shield-like structure attached to the embryo but here in Long Section we see only a thin slice. Go to the whole grain photographs and the micrographs in Grain Filling 2 and 3 to see where it fits between the embryo and the endosperm. The densely cytoplasmic cellular endosperm has been completely used by 15 days after flowering. |
 | This highly magnified section, at 11days after flowering, shows more detail of the embryo. Cellular patterning is seen in the root pole. The cleft on the dorsal side (arrowed) defines the point of separation of the epicotyl, the primordial shoot, from the scutellum. A group of cells on the dorsal side are highly meristematic and will soon differentiate into the shoot apex. The cellular endosperm declines and, as the scutellum develops, the embryo will be supported from the starch reserves in the main body of the endosperm. |
 | Each day brings further development of the scutellum and differentiation of the three elements of the embryonic axis; shoot, root and mesocotyl. In this section the primordial shoot apex can be seen inside the coleoptile. 16 days after flowering. |