The genus Cinnamomum

Botany and Crop Improvement of Cinnamon and Cassia 59
Based on the chemical evolution Guang-Fu and Yang (1988) have suggested the
probable interrelationships among these species.
Cytology
The earliest cytological study was that of Tackholm and Solderberg (1917), who reported
the somatic number as 2n 24 in C. sieboldii. Sugiura (1936) and later Chuang et al.
(1963) reported the same number in C. camphora, C. japonicum, C. linearifolium,
C. obtusifolium, C. sieboldii and C. zeylanicum. Sharma and Bhattacharya (1959), in
a detailed study on four species (C. camphora, C. verum, C. tamala and C. iners), found
2n 24 consistently in all of them. Mehra and Bawa (1968, 1969) found the same
number in C. camphora, C. caudatum, C. cecidodaphne, C. impressinervium, C. obtusifolium
and C. tamala. Okada (1975) and Okada and Tanaka (1975) carried out cytological
studies on Japanese Lauraceae, including five species of Cinnamomum, and confirmed
the same chromosome number in all of them. These authors could establish clear
cytological differences based on the nature of the interphase nuclei, which lends support
to the subdivision of Laureaceae into the subfamilies Lauroideae and
Cassythoideae.
In C. camphora, as well as in other species studied by Okada (1975), chromosomes can
be distinguished by their size, position of centromere as well as satellite and location of
heterochromatic segments (Fig. 2.19, a–c). In interphase nuclei, chromatin forms about
20 condensed bodies, which are stained darkly and are round or rod shaped. Speciesspecific
chromatin distribution is also noticed. In C. camphora the 5th pair (chr. 9, 10,
satellite chromosomes) shows the following chromatin distribution: the satellites and
the long arms are euchromatic (Fig. 2.19, a). In the 7th pair (chr. 13, 14) there are heterochromatic
regions in the proximal regions of short arm and in the long term. The
distal regions of the short arms consist of late condensing chromatin. The twelth pair
is composed of a heterochromatic segment in the proximal region of the short arm, of
euchromatin in the long arm and of late condensing chromatic segments in the distal
region of short arms. In C. daphnoides the morphological characteristics of the chromosomes
at interphase, prometaphase and metaphase are more or less the same as that of
C. camphora. The satellite chromosome pair (9, 10) showed a different chromatin pattern
from those of C. camphora. All of the satellite and proximal regions of both arms
consisted of heterochromatin and the distal region of the long arm was euchromatin. In
C. sieboldii the distribution of chromatin was also found to resemble that in C. camphora
but differed in the two pairs of satellite chromosomes. The eighth pair (15, 16) showed
the distribution pattern as follows: euchromatin located in the distal region of long arm
and in all of the satellite. Heterochromatin was found in the proximal regions of both
arms. The other satellite chromosomes (23, 24) possessed euchromatic segments in all
of the satellite in the proximal region of the short arm and the distal region of the long
arm, and a hetrochromatic segment in the proximal region of the long arms. At
metaphase the secondary constructions of these chromosomes were invisible probably
due to heavy condensation (Okada, 1975).
Propagation
Cinnamon and cassia can be propagated either through seeds or clonally by cuttage.
Seed is recalcitrant and loses viability quickly when stored. When sown immediately
after harvest, seeds give 90–94% germination, while on storage for five weeks the