Definition of testa in English:



  • The protective outer covering of a seed; the seed coat.

    • ‘Seeds consist of three parts with different genetic compositions: the embryo and endosperm of zygotic origin and the seed coat or testa derived from maternal tissues.’
    • ‘Stromules were present in the epidermal cells of the plumule and radicle on emergence from the testa; clumps of plastids interconnected with stromules 8-10 m long were especially prevalent in the root epidermis.’
    • ‘The single-seeded fruit known as a caryopsis consists of the pericarp and testa surrounding the endosperm and the embedded embryo.’
    • ‘Wheat grains consist of the seed coat, or testa, which surrounds the endosperm and embryo.’
    • ‘Except at the crease, the endosperm is encased in the testa with its inner and outer cuticular layers and so, from this stage onwards, only the symplastic pathway through the chalazal cells is available.’
    • ‘A reddish tinge signifies penetrance of the dye through the testa into the endosperm and embryo.’
    • ‘The endosperm cap (the testa included) was placed on the needle and was pierced by moving the needle down into a polyvinyl chloride block with a conic hole with a minimum diameter of 0.7 mm.’
    • ‘The outer testae were removed and seeds placed in the light on filter paper soaked with sterile distilled water.’
    • ‘Most of the wheat consumed by humans is processed from white flour, which is produced by milling to remove the germ and bran (pericarp, testa, nucellar layer, and aleurone layer).’
    • ‘The mature achene is composed of a hard and relatively thick pericarp, a thin testa, an endosperm consisting of one cell layer, and a small embryo.’
    • ‘To facilitate detection of the red colour, the testa of the seeds was bleached with 10% sodium hypochlorite.’
    • ‘In plants, ethanol is produced in seeds with an oxygen-impermeable testa, root tips, and the deep tissues of ripening fruit where there is a high demand for oxygen.’
    • ‘Freshly harvested seeds of hazel exhibit primary dormancy imposed by inhibitory substances, such as abscisic acid, present in the testa and pericarp.’
    • ‘The brownseed mutants (bs, bs, and bs) of tomato all possess dark testae and deleteriously affect seed germination speed and/or final percentage.’
    • ‘Beans were soaked, the testae were removed, and the flour was milled and dried.’
    • ‘The seeds' hard testa is an effective protective structure allowing them to survive fire, and being passed through the guts of large animals which aid dispersal.’
    • ‘I observed no wild type seeds with thick testae in the subsamples.’
    • ‘While the subaleurone cells were intensively labelled, no label was seen in the outer layers of the grain, i.e. in the testa, pericarp and husk.’
    • ‘In those studies, the fast-drying condition was normally referred to as the dehydration of seed tissues under a laminar flow cabinet or with silica gel, while slow-drying was the drying of seed tissues with testa or in closed containers.’
    • ‘Sufficient moisture must be present to penetrate the testa or seed coat, but not so much that the seed rots or that the oxygen level in the soil is reduced.’


Late 18th century: from Latin, literally tile, shell.