The genus Cinnamomum

50 P.N. Ravindran et al.
Embryosac
A group of hypodermal cells and one or two cells of the nucellus below them get
differentiated into the primary archesporial cells in the young ovule. Only one of them
is functional. The nucleus of this cell undergoes meiotic division, giving rise to a linear
tetrad of megaspores, of which the chalazal one is functional while the other three
degenerate. This nucleus undergoes three mitotic divisions, giving rise to an eightnucleated
embryosac with the 3 2 3 arrangement. The mature embryosac is
narrow, elongated and develops numerous small vacuoles (Fig. 2.15). The synergids
persist, while the antipodals degenerate before fertilisation (Sastri, 1958).
Embryo
1
3
4
2
Sastri (1958) studied the embryo development in C. iners, and the process is believed to
be the same in other species, including cinnamon. The zygote divides transversely
producing two superposed cells, the apical cell (ac) and the basal cell (bc) (Fig. 2.16).
They then divide by vertical walls resulting in a four-celled proembryo. One of the
daughter cells derived from ac divides by means of an oblique wall and a triangular
cell (the epiphyseal initial, e) is formed and this cell undergoes further division only
at a much later stage. The remaining cells undergo many divisions giving rise to
the many-celled proembryo (Fig. 2.16). The subepiphyseal cells undergo transverse
5
Figure 2.15 Stages in the development of embryosac. 1. L.S. of ovule at 4 – nucleate embryosac stage
showing nucellar cells with prominent nuclei. 2. L.S. of apical region of ovule showing
synergids 3. L.S. of chalazal portion of nucellus showing antipodal cells. 4. Apical portion
of embryosac showing egg apparatus. 5. L.S of embryosac showing endosperm
nuclei and two-celled proembryo (1–3, 5: C. iners; 4: C. verum). (After Sastri, 1958.)