plants-seeds-5 - food The food reserve necessary for...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Seeds and germination - wheat ‘Seed’ structure . The wheat grain is really a fruit, containing one seed. The thin ovary wall is fused with the testa and does not interfere with germination. Germination The fruit absorbs water, swells, and a radicle bursts through the fruit wall. Shortly after, other radicles emerge from the fruit, developing equally so that there is no main root. Root hairs grow on the upper regions. The plumule grows straight up and through the fruit wall, but the growing point and first leaves are protected by a sheath, the coleoptile , with a hard, pointed tip. Once above the soil the first leaves burst out of the coleoptil e which remains as a sheath round the leaf bases. The cereals, maize, wheat, barley, oats etc. are all monocotyledons, having only one cotyledon in the seed. Unlike the dicotyledonous plants, the single cotyledon does not contain a store of
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: food. The food reserve necessary for germination is stored in the endosperm, mainly as starch . When the grain absorbs water, enzymes are activated. These enzymes digest the starch in the endosperm to soluble sugar. The cotyledon absorbs the sugar and passes it to the rapidly growing radicle and shoot. region of attachment to stalk position of plumule position of radicle endosperm fruit wall and testa cotyledon plumule radicle Wheat grain (a) external appearance (b) longitudinal section plumule more conspicuous beneath fruit wall radicle emerges fruit wall splits plumule in sheath (coleoptile) first leaf coleoptile breaks open roots root hairs Germination of wheat more roots appear © D.G. Mackean 5 Wheat...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online