testa
plant anatomy
Also known as: seed coat
Quick Summary
cotyledons and germination
(Top) Monocotyledon (internal structures of a corn seed with stages of germination). Nutrients are stored in the cotyledon and endosperm tissue. The radicle and hypocotyl (region between the cotyledon and radicle) give rise to the roots. The epicotyl (region above the cotyledon) gives rise to the stem and leaves and is covered by a protective sheath (coleoptile). (Bottom) Eudicotyledon (internal structures of a bean seed with stages of germination). All nutrients are stored in the enlarged cotyledons. The radicle gives rise to the roots, the hypocotyl to the lower stem, and the epicotyl to the leaves and upper stem.
The testa is the protective outer covering of a seed, derived from the ovule's integuments. It shields the embryo and any nutritive tissue within the seed. The testa can vary in texture, from hard and stony to having a fleshy outer layer (sarcotesta) and an inner stony layer (sclerotesta). Some seeds may also have additional coverings like wings or prickles. The testa plays a crucial role in protecting the seed from environmental factors and predators, ensuring the survival of the embryo until germination.12
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