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The seed coat forms from the two integuments or outer layers of cells of the ovule, which derive from tissue from the mother plant, the inner integument forms the tegmen and the outer forms the testa. (The seed coats of some monocotyledon plants, such as the grasses, are not distinct structures, but are fused with the fruit wall to form a ...
The stages of germination of a pea plant: A. seed coat, B. radicle, C. primary root, D. secondary root, E. cotyledon, F. plumule, G. leaf, H. tap root. The part of the plant that first emerges from the seed is the embryonic root, termed the radicle or primary root. It allows the seedling to become anchored in the ground and start absorbing water.
Breaking dormancy, or finding the specific requirement of the seed, can be rather difficult. For example, a seed coat can be extremely thick. According to Evert and Eichhorn, very thick seed coats must undergo a process called scarification, in order to deteriorate the coating. [12] In other cases, seeds must experience stratification.
Bloodroot is one of many plants whose seeds are spread by ants, a process called myrmecochory. The seeds have a fleshy organ called an elaiosome that attracts ants. The ants take the seeds to their nest, where they eat the elaiosomes, and put the seeds in their nest debris, where they are protected until they germinate.
Scarification is often done mechanically, thermally, and chemically. The seeds of many plant species are often impervious to water and gases, thus preventing or delaying germination. Any process designed to make the testa (seed coat) more permeable to water and gases is known as scarification.
As the embryo and endosperm develop, the wall of the embryo sac enlarges and combines with the nucellus and integument to form the seed coat. The ovary wall develops to form the fruit or pericarp, whose form is closely associated with type of seed dispersal system. [68] Other parts of the flower often contribute to forming the fruit. For ...
Primary – root that develop from the radicle of the embryo, and is normally the first root to emerge from the seed as it germinates. Root Hairs – very small roots, often one cell wide, that do most of the water and nutrient absorption. Secondary – roots forming off of the primary root; often called branch roots.
As the plant embryo grows at germination, it sends out a shoot called a radicle that becomes the primary root, and then penetrates down into the soil.After emergence of the radicle, the hypocotyl emerges and lifts the growing tip (usually including the seed coat) above the ground, bearing the embryonic leaves (called cotyledons), and the plumule that gives rise to the first true leaves.