22,3 Reyes: Woods of the Philippine Dipterocarps 321 



Microscopic features.— Vessels large (228 to 273 /* in diam- 

 eter), occasionally occluded with tyloses. Tracheids wanting, 

 as in Anisoptera. Fiber tracheids prominent, proximate to the 

 vessels. Libriform fibers more regularly arranged radially than 

 in Anisoptera, averaging 26 by 1,700 /t in size. Vertical 

 parenchyma vasicentric and diffuse. Resin cysts diffuse; 

 epithelial cells flattened. Idioblasts absent. Wood rays 3 to 5 

 by 40 to 50 cells in transverse section. 



Remarks. — The woods of the three species of Dipterocarpus 

 are so similar in their gross and minute anatomy that it seems 

 undesirable to attempt to separate them in a key. 



DIPTEROCARPUS GRANDIFLORUS Blanco. ApITONG. (Plate 11.) 



Gross features. — See Gross Features of the apitong group. 



Microscopic features.— Vessels large, 162 to 324 p. (average, 

 263) in diameter, numerous, rounded ovoid or oblong in trans- 

 verse section, solitary or in groups of 2 to 6 ; tyloses relatively 

 few, distinct. Tracheids wanting. Fiber tracheids prominent, 

 proximate to the pores. Libriform fibers numerous, 26 by 1,690 

 /i. Vertical parenchyma vasicentric and diffuse, the latter in 

 tangential strings of 2 to 7 cells, not as prominent as in D. ver- 

 nicifluus. Resin cysts diffuse or occasionally in groups of 2 to 

 4 and then in interrupted concentric rows, rounded in transverse 

 section, epithelial cells flattened. Idioblasts wanting. Wood 

 rays 3 by 40 cells in transverse section. 



Remarks.— Used for ordinary construction and medium-grade 

 furniture. Not durable when exposed but lasting an indefinite 

 period when protected from moisture. In the temperate regions 

 where termites (white ants) and fungi are less destructive, 

 apitong will make desirable wood for railroad ties and 

 structural timbers where a strong hardwood is required. Like 

 other members of the genus, apitong is easily impregnated with 

 preservatives. The wood of this species is occasionally sub- 

 stituted for giho, a higher grade of timber. Dipterocarpus 

 grandiflorus is widely distributed in the islands from Cagayan 

 southward to Agusan and is one of the most abundant of the 

 dipterocarps. 



DIPTEROCARPUS VERNICIFLUUS Blanco. PANAU. (Plate 12.) 



Gross features.— The wood is very similar to apitong in 

 general appearance but is of somewhat coarser texture; specific 

 gravity, 0.699. 



Microscopic features. — Vessels large, 73 to 

 273) in diameter, ovoid or oblong 



