Qualitative Anatomical Characteristics of Compression, Lateral, and Opposite Woods in Pinus merkusii and Agathis loranthifolia

This study aimed to observe and compare the qualitative anatomical characteristics of compression (CW) , lateral (LW) , and opposite (OW) woods in the stem wood of Sumatran pine ( Pinus merkusii ) and Agathis ( Agathis loranthifolia ) . The anatomical characteristics were observed using optical microscopy and scanning electron microscopy. CW showed a gradual transition from earlywood to latewood in both species, circular tracheid shape, many intercellular spaces, irregular tracheid tips, helical cavities, and slit-like bordered pit s . CW of Sumatran pine showed an indistinct growth ring, while CW of Agathis showed a distinct growth ring. Helical ribs occurred only in CW of Sumatran pine. LW and OW showed an oval tracheid with an angular outline, regular tracheid arrangement, and tapered tracheid tips in both species. LW and OW showed mainly uniseriate bordered pits in Sumatran pine, while LW and OW of Agathis frequently showed multiseriate bordered pit s . CW, LW, and OW showed fusiform and uniseriate rays in Sumatran pine, while those of Agathis showed uniseriate rays. In conclusion, CW showed distinctive qualitative anatomical characteristics to LW and OW in both species, while LW and OW mainly showed similar characteristics. In particular, there were considerably distinctive characteristics between CW from both species. Keywords:  Agathis, anatomical characteristics, reaction wood, Sumatran pine