The genus Cinnamomum

Botany and Crop Improvement of Cinnamon and Cassia 53
Seed shows differentiation of procambial vascular supply. In the fertilised ovule, the
outer integument is many layered while the inner is two-to-four layered. After fertilisation
the inner integument gradually disintegrates and is absent in the mature seed.
The outer integument gradually increases in thickness and the outer epidermal cells
become filled with tannin. The cells of the inner epidermis acquire band shaped helical
thickening. In between them there are eight to ten layers of parenchymatous cells
(Sastri, 1958).
Cassia buds
Cassia bud is an item of commerce and consists of dried immature fruits of C. cassia.
They vary from about 6 to 14 mm in length, the width of the cup varying from about
4–6 mm. The immature fruit is enclosed within the calyx cup. Dried cassia buds have
a sweet, warm, pungent taste similar to that of cassia bark.
Parry (1969) has provided a detailed description of the histology of the cassia bud,
on which the following discussion is based (Fig. 2.18). The calyx lobes consists of:
(i) an outer epidermis of small cells, rectangular or nearly so, with thick outer walls; (ii)
a cortex of parenchyma cells, secretion cells and occasional stone cells; and (iii) fibrovascular
tissue consisting of short and long parenchyma. The short fibres are porous
with numerous pits. The long fibres are pitted and striated. Phloem cells are numerous.
Xylem vessels are small and consist of annular, spiral and reticulate types. There is an
inner epidermis of small, rectangular cells, similar to that of the outer epidermis.
Calyx tube: The calyx tube consists of the following parts: (i) an epidermis of small
cells, rectangular or nearly so, with thick outer walls; (ii) a cortex of parenchyma cells,
isodiametric that are about 45 in diameter, secretion cells about 66 in diameter; and
occasional stone cells. The cell contents are light to dark brown in colour; (iii) a pericycle
marked by a ring of fibres, the ring is broken by the parenchymatous tissue of pith rays.
The fibres are thick-walled and up to about 66 in diameter; (iv) fibrovascular tissue
similar to that of the calyx lobes; and (v) pith of isodiametric, parenchymatous cells and
occasional stone cells.
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Figure 2.18 Longitudinal section of “cassia bud” (young fruit). 1. Pedicel; 2. Calyx; 3. Mesocarp;
4. Endocarp; 5. Reticulate cells; 6. Pigmented parenchyma; 7. Exocarp; 8. Pericarp;
9. Compressed parenchyma; 10. Cotyledon. (Source: Parry, 1969.)