Comparative Study on the Leaf Structures of Sonneratia caseolaris and S. apetala

This study investigated the potential endanger of alien plant Sonneratia apetala. The leaf structures of S.caseolaris and S.apetala were studied by paraffin sectioning under a light microscope. Results showed that both S.caseolaris and S.apetala had isobilateral leaves; the midrib vascular bundle was amphicribral; the leaves had four veins, with the primary vein having a semi-amphicribral vascular bundle; the mesophyll of the mature leaves had aqueous tissues, crystal cells, tannin cells and stone cells; the salt glands were developed from the epidermis cells of the leaves, experiencing three periods. As an alien plant species, compared with S.caseolaris, S.apetala had a faint cambium, better-developed vascular tissues, more crystal and tannin cells in the storage tissues, and more chloroplasts in the palisade. Furthermore, S.apetala had obviously better ecological adaptability than S.caseolaris. Thus, S.apetala may become an invasive plant.