Comparative study on leaf morphology and structure of different ages of Aegiceras corniculatum

The morphology and organizational structure of mature leaves of different ages（1 year，2 year and4 year）of Aegiceras corniculatum plants were comparatively studied by adopting paraffin section method and microscopicobservation. Results indicated that leaf area increased with plant age，namely the average leaf area of 4-year plants wassignificantly larger than those of 1-year and 2-year plants，whereas the specific leaf weight remained basically unchangedand the leaf length to width ratio demonstrated a trend of reduction with plant age；as the plant age of A. corniculatumincreased from 1-year to 2-year and to 4-year，the thickness of palisade tissue and sponge tissue，the organizationalstructure closely degrees and organizational structure loose degrees all demonstrated a trend of declining first then risingagain，so that the organizational structure closely degrees and organizational structure loose degrees of 4-year plant leaveswere significantly larger than that of the younger plants. No significant difference was observed between the size of upperepidermal cells and lower epidermal cells；the cuticle thickness of upper epidermis increased with plant age，whereas thecuticle thickness of lower epidermis decreased with plant age；the slat gland cells significantly enlarged with plant age. Theresults indicated that plant age had significant effect on leaf morphology and organizational structure of A. corniculatum.