testa(n = noun.plant) episperm, seed coat - protective outer layer of seeds of flowering plants;
is a kind of reproductive structure
is a part of seed
Derived form adjective testaceous₁

1.  The external hard or firm covering of many invertebrate animals. [1913 Webster]
" The test of crustaceans and insects is composed largely of chitin; in mollusks it is composed chiefly of calcium carbonate, and is called the shell." [1913 Webster]

2.  The outer integument of a seed; the episperm, or spermoderm. [1913 Webster]

testa, n. (pl. testae) Bot. a seed-coat.

Etymology:
L (as TEST(2))