1.  stemma(n = noun.shape) - a tree diagram showing a reconstruction of the transmission of manuscripts of a literary work;

2.  stemma(n = noun.group) ancestry, blood, blood line, bloodline, descent, line, line of descent, lineage, origin, parentage, pedigree, stock - the descendants of one individual; "his entire lineage has been warriors"

3.  stemma(n = noun.body) ocellus, simple eye - an eye having a single lens;

   One of the ocelli of an insect. See Ocellus. [1913 Webster]

stemma, n. (pl. stemmata)
1 a family tree; a pedigree.
2 the line of descent e.g. of variant texts of a work.
3 Zool. a simple eye; a facet of a compound eye.

Etymology:
L f. Gk stemma wreath f. stepho wreathe