IUI.C, 3 Foxworthy: Philippine Dipterocarpaceae, II 175 



Key to the Philippine genera of Dipterocarpaceae. 



a 1 . Lobes of fruiting calyx usually shorter than fruit and not extending 

 beyond it. 



b 1 . Calyx-lobes round and recurved; stamens 30 to 60 7. Isoptera. 



b'. Calyx-lobes not as above; stamens 10 or 15 8. Balanocarpus. 



a % . Lobes of fruiting calyx longer than fruit. 



6\ Calyx-tube enclosing fruit; two lobes expanding into long wings. 

 c 1 . Stipules large, amplexicaul, calyx-tube free; stamens 8; style 



filiform \ 1. Dipterocarpus. 



c*. Stipules small, deciduous, fruit connate with calyx-tube stamens 



20 to 35; style short 2. Anisoptera. 



6*. Calyx-tube not enclosing fruit. 



c\ Fruit with five long wings 6. Parashorea. 



c*. Fruit with three long wings. 



d 1 . Anthers with five pointed appendages 4. Pentacme. 



d*. Anthers with less than five appendages 5. Shorea. 



e*. Fruit with two long wings. 



d 1 . Calyx imbricate in bud 3. Hopea. 



d 1 . Calyx valvate in bud 9. Vatica. 



1. DIPTEROCARPUS Gaertner f. 



The members of this genus are rather uniform in habit but 

 occupy a tolerably wide range of habitats. Some forms, as 

 Dipterocarpus grandiflorus Blanco, are often found on rather 

 exposed forested ridges; while others, such as D. pilosus Roxb., 

 are characteristically found in moist lowland forests. The wood 

 is very uniform in structure and is known in the market 

 as apitong. It is the most abundant Philippine timber, making 

 up about 17 per cent by volume of our forests. 



Since the publication of my previous paper we have found 

 representatives of all of the sections of the genus, as arranged 

 by Dyer, except the section Plicati, which has not yet been found 

 in the Islands. 



At the present time about seventy-five species are known in 

 the genus, seventeen of which are known from the Philippines. 

 Six of the Philippine species are known from outside the Archi- 

 pelago. These are Dipterocarpus pilosus Roxb., known from 

 Burma, the Andamans, Sumatra, and Bangka; D. trinervis 

 Blume, from Java; D. gracilis Blume, from Java; D. hasseltii 

 Blume, from Malacca, Sumatra, and Java; D. grandiflorus 

 Blanco, from the Malay Peninsula, Bangka, and Borneo; and 

 D. orbicularis Foxw., from British North Borneo. 



Key to the Philippine species of Dipterocarpus. 

 a 1 . Fruit not angled, usually globose (§ Sphaerales Dyer). 



b\ Leaves small (10 to 13 cm long, 2 to 3.5 cm broad), narrow, long- 

 caudate-acuminate 8. D. caudatus. 



b*. Leaves larger, not long-caudate-acuminate. 

 c\ Fruit less than 2 cm in diameter. 



