Integument is the exterior or the outermost covering of an ovule. Testa, on the other hand, is the exterior or outermost seed covering. In sexual reproduction, both the gametes fuse, forming a zygote (diploid). Ovary carries the ovule, which in turn is protected by the covering known as integuments. Seeds are developed from the ovule once fertilization occurs while integument develops into the seed coat referred to as testa.
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Integument
- Outermost protective covering of the ovule
- Angiosperms have two integuments while gymnosperms have one integument layer
- It comprises living cells and is smooth and thin
- Does not possess sclereids
- Nucleus found at the micropyle opening to promote the entrance of pollens into ovule for syngamy
- It is a pre fertilization structure, hence develops into testa once fertilization takes place
Testa
- Exterior protective covering of the seed
- Outer integuments emerges into testa and is brown in appearance
- It is a post-fertilization structure
- Two layers of testa – exotesta and endotesta, chiefly safeguarding the embryo that is developing
- Also protects the seed while the seed disperses
- It consists of sclereids as it is hard and thick
- As it is impermeable to water it results in seed dormancy at times
Difference Between Integument and Testa
Following are some of the important differences between Integument and Testa.
| Integument | Testa |
| Outermost protective covering | |
| Of ovule | Of seed |
| Nature of cells | |
| Living.
Thin and smooth |
Non-living
Thick and hard |
| Fertilization stage | |
| Pre-fertilization structure | Post-fertilization structure |
| Sclereids | |
| Absent | Present |
| Seed dormancy | |
| No role | Impermeable to water, hence plays a key in seed dormancy |
| Origination | |
| Arise from the chalazal ending of the ovule | From outer integument of ovule, once fertilization takes place |
| Function | |
| To protect the ovule | To protect the developing embryo |
| Permeability | |
| Permeable to water | Impermeable |
Those were some differences between integument and testa. Watch this space at BYJU’S for more such differences for NEET.
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