22,5 Reyes: Woods of the Philippine Dipterocarps 337 



ness, arranged in distinct radial rows. Vertical parenchyma 

 vasicentric- to diffuse-zonate. Resin cysts in interrupted con- 

 centric rows. Vertical idioblasts present. Horizontal idioblasts 

 wanting. Wood rays small (3 or 4 by 60 cells) ; organic in- 

 filtration conspicuous. 



Remarks. — Used for permanent construction, shipbuilding, 

 and bridges, owing to its strength and durability. One of the 

 best structural timbers of the Islands and obtainable in quantity 

 in large sizes. 



Shorea balangeran is reported from Luzon southward to Zam- 

 boanga and reaches the local markets in appreciable quantities. 



SHOREA GUISO (Blanco) Blume. Gmo. (Plate 28.) 



Gross features. — Sapwood light gray, thin; heartwood red- 

 dish brown to brown. Wood fine to medium textured; cross 

 grained, medium hard to hard, moderately heavy to heavy; 

 specific gravity, 0.812. 



Microscopic features. — Vessels numerous, small, 64 to 205 p. 

 (average, 137) in diameter, rounded or oblong, solitary or 

 in groups of 2 or 3; tyloses sparse. Tracheids rare. Fiber 

 tracheids wanting. Libriform fibers numerous, small (19 by 

 1,370 fi) , with walls 6.4 /* in thickness, arranged in radial rows. 

 Vertical parenchyma vasicentric to vasicentric-zonate, occa- 

 sionally diffuse. Resin cysts in interrupted concentric rows. 

 Vertical idioblasts prominent. Horizontal idioblasts wanting. 

 Wood rays small (3 or 4 by 40 cells). Organic infiltration 

 copious, especially in the wood rays. 



Remarks.— Used for general construction, houses, and is the 

 favorite wood for vehicle parts. Not durable when exposed or 

 in contact with the soil. Probably the best-known dipterocarp 

 of the Islands, not only on account of its wide distribution but 

 also because of the general utility of the wood. Often sub- 

 stituted for the coarse-textured yakals such as gisok and mala- 

 yakal, from which it differs in its lighter, softer, reddish (in 

 contrast to yellowish gray) wood. On the other hand, the api- 

 tongs are substituted for it in the market but are to be dis- 

 tinguished in that the various species of Dipterocarpus are coarse 

 textured and exhibit diffuse resin cysts. 



Shorea guiso is widely distributed throughout the Archipelago 

 from Cagayan southward to Zamboanga. 



THE MANGGACHAPUf GROUP 



The manggachapui group is wholly confined to the genus 

 Hopea and takes its name from the best-known species, Hopea 



