Testa
Definition
The seed coat, derived from the integuments of the ovule. Its surface sculpture (smooth, reticulate, foveolate, echinate, and so on) is a major diagnostic character for seed identification at genus and species level.
- Surface types
- Smooth, reticulate (net-patterned), foveolate (pitted), echinate (spiky), and others
- Identification level
- Genus and species level
- Examination method
- Low magnification microscopy
- Origin
- Derived from the integuments of the ovule
Common questions
What is the testa and why does it matter in forensic work?+
The testa is the seed coat, the protective outer layer of a seed. In forensic investigations, its surface patterns like nets, pits, or spines are distinctive enough to identify seeds down to genus and species level, which is crucial when you're trying to link botanical evidence to a crime scene or suspect.
How do examiners use the testa to identify seeds?+
They look at the surface sculpture under low magnification. Common patterns include smooth finishes, reticulate (net-like) surfaces, foveolate (pitted) surfaces, and echinate (spiky) surfaces. Each plant species has its own characteristic testa pattern, making it a reliable identifier even when only seeds are recovered from evidence.
Can testa identification work when you only have seeds?+
Yes. For example, opium poppy seeds have a distinctive net-patterned testa visible under basic magnification, so forensic examiners can confirm seed identity and link it to a plant source using testa features alone.
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Explained in these topics
- Leaf and Seed Evidence: Identification and TransferThe seed coat, derived from the integuments of the ovule. Its surface sculpture (smooth, reticulate, foveolate, echinate, and so on) is a major diagnostic char...
- Botanical Identification of Other Controlled Plant SpeciesThe seed coat. In Papaver somniferum, the testa has a reticulate (net-patterned) surface that is visible under low magnification and is a useful identifier whe...