312 The Philippine Journal of Science 1923 



features may not be out of place here as indicative of the ex- 

 tremes which may be expected. 



The color ranges from light yellow which is found in all 

 species of Anisoptera, and in Hopea acuminata Merrill, H. 

 pierrei Hance, H. philippinensis Dyer, Isoptera borneensis 

 Scheffler, and Shorea balangeran (Korthals) Dyer, to dark red- 

 dish brown as in Hopea plagata Vidal. Shades of red predom- 

 inate in all species of Dipterocarpus, Shorea polyspermia 

 Merrill, S. negrosensis Foxworthy, S. palosapis (Blanco) Mer- 

 rill, S. teysmanniana Dyer, and S. guiso (Blanco) Blume. Cer- 

 tain forms, such as Balanocarpus cagayanensis Foxworthy 

 and Hopea mindanensis Foxworthy, posses wood which, when 

 green or freshly exposed, exhibits a greenish cast or grass green 

 streaks, the color changing to dark brown with age (oxidation) 

 and exposure to light. 



Dipterocarp wood is coarse textured as a rule, a condition 

 which is occasioned more by the large size of the vessels than 

 by increased dimensions of the remaining elements. In fact, 

 the coarsest commercial timbers of the Islands belong in this 

 family, and only a few species of the family, such as Vatica 

 mangachapoi Blanco and forms of Hopea and Balanocarpus, 

 exhibit fine texture. 



Finally, a surprising range of weight, hardness, strength, 

 and durability is to be noted in the group, which may be illus- 

 trated by reference to woods representing the two extremes. 

 Shorea palosapis (Blanco) Merrill is soft and light (specific 

 gravity, 0.340) 31 and is not, in a strict sense, a structural tim- 

 ber. The opposite extreme is represented by such a wood as 

 Hopea plagata (specific gravity, 1.202), which is very hard 

 and very heavy and makes an excellent structural timber. 

 Between these extremes all variations in weight, hardness, and 

 strength occur. Durability in contact with the soil is in general 

 directly proportional to weight, a condition which does not al- 

 ways hold for woods of the temperate regions nor for those 

 of many tropical families. The softer, lighter dipterocarps of 

 the genera Anisoptera, Dipterocarpus, Shorea, Pentacme, and 

 Parashorea are not durable in contact with the ground, while 

 the harder, heavier forms, such as Isoptera borneensis, Shorea 

 balangeran, and Vatica species, are noted for their lasting 

 qualities. 



le on mature woods (heart- 



