Source: Shylaja, 1984.
C. camphora and in C. cassia while C. verum and C. malabatrum have a higher frequency. Guard cell dimensions do not show much variation among species except in C. camphora, in which the dimensions are higher than those in other species.
Metcalfe and Chalk (1950) and Kasapligal (1951) were of the opinion that stomata in Lauraceae were paracytic (Rubiaceous), i.e. that they remain surrounded by two subsidiary cells placed parallel to the pore. Pal (1974) reported that in C. camphora and C. zeylanicum (C. verum) stomata were anomocytic, i.e. stomata were surrounded by a number of epidermal cells that were not differentiated into subsidiary cells. Kostermans (1957) and Avita and Inamdar (1981) were of the opinion that stomata in Cinnamomum were paracytic. Shylaja (1984) confirmed anomocytic stomata in C. verum, C. cassia, C. malabatrum, C. perrottettii, C. riparium, C. macrocarpum and paracytic stomata in C. camphora.
The process of anomocytic stomatogenesis in C. verum was outlined by Pal (1978) and Shylaja (1984). In young leaves, epidermal cells are regularly arranged, straight walled and polygonal. Stomata differentiation initiates when leaves attain a length of 11—15 mm and a width of 5—8 mm. The development of stoma begins when an epidermal cell differentiates into a protoderm cell by the formation of a septum that produces two unequal cells (Fig. 2.7). The smaller cell is lenticular in shape, having a prominent nucleus. This cell functions as the meristemoid, while the larger cell becomes a normal epidermal cell. The meristemoid increases in size, becomes almost circular and divides vertically to form two equal or sometimes unequal guard cells. These guard cells enlarge and become kidney shaped, leaving a pore in the centre. As the leaf enlarges the epidermal cell walls become sinuous in C. verum and in many other species. At this stage four to five neighbouring cells of various shapes and sizes surround the guard cells. The meristemoid directly acts as guard cell mother cell, and the neighbouring cells are derived from other protoderm cells, hence the development is perigenous type.
Anomocytic stoma is generally regarded as the primitive type and occurs in the primitive land plants such as Psilophytales. The paracytic type is also primitive, occurring in Equisetales, but it is derived from the anomocytic type. In this genus different types of stomata have been reported. Such developmental variations are common in any genus
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