64 XVII. DIPTEROCARPACEJ] 



the central cylinder and run through the hark hefore they enter the petiole. There 

 are generally three leaf traces, one apical, two lateral, all consisting of a vascular 

 bundle with one or several resin ducts in the pith. In some cases these traces run in 

 the bark through an entire internode, 



Structure 0/ jpeiioZe.— The 3 vascular bundles, which enter the petiole, forming its 

 central cylinder, remain distinct in rare cases. As a rule they ramify and coalesce, 

 forming at the base of the petiole an intricate mass of xylem and phloem with a 

 number of resin ducts, and in most species the internal structure of the petiole changes 

 in its progress from the base to the blade. For systematic purposes it is convenient to 

 examine the petiole immediately below the base of the blade. At this point we frequently 

 find a semicircle of vascular bundles, more or less united, each with its resin duct, 

 and inside this semicircle one or several vascular bundles with or without resin ducts. 

 Structure of wood. — Vessels moderate-sized, often in groups, enclosed in a narrow 

 white ring consisting of wood parenchyma. Medullary rays fine and moderately 

 broad, generally equidistant, the horizontal cells of these in many cases very long, 

 3 mm. in Dipterocarpus alatus. These longitudinal cells, as well as the resin ducts in 

 the younger wood, are filled with essential oil. Many species have a distinct dark- 

 coloured heartwood. Eesin ducts, vessels, fissures and other cavities in the old wood 

 are filled with resin. 



Biological features. — As a rule large trees, with tall, regularly shaped trunks. 

 "With few exceptions they do not bear flowers and seed until they have attained a 

 considerable age. As a rule they seed annually, though the quantity of seed produced 

 varies from year to year. In the Malay Peninsula and in Ceylon, however, there are 

 species which flower periodically, some every sixth year. The seed germinates soon 

 after ripening, in some cases before it falls to the ground. Several species (Sal, 

 Eng) are gregarious and form forests of considerable extent, in which they prevail over 

 their coinjjanions. 



Geographical distribution. — The Order is limited to the Indo-Malayan region, from 

 the Seychelles to New Guinea. Of the 325 species (in 16 genera) at present known, 30 

 are here described. Of species found elsewhere may be mentioned : (1) Dryobalanops 

 aromatica, Gaertn. f., Johore, Sumatra, Borneo, and probably on the Philippine Islands, 

 yields the Borneo camphor, which is deposited in cavities in the wood in the shape of 

 beautiful colourless or light yellow crystals. (2) Shorea selanica, Blurne, Amboina, 

 produces large quantities of transparent amber-like resin, hanging down from the 

 branches in conical or cylindrical masses, often as thick as a man's leg. (3) Several 

 species, the seeds of which contain fat resembling tallow ( Tang kaioang), which is an 

 important article of trade in the Malay Archipelago. The chief of these are : Shorea 

 stenoptera, Burck; S. aptera, Burck ; S. gysbertiana, Burck ; and S. pinanga, Scheffer, 

 all in Borneo ; Isoptera borneensis, Scheffer, Malay Peninsula, Bangka, Borneo. 



The Order divides itself naturally into 5 tribes and 16 genera. One tribe (Dryobalan- 

 opseoz) and 7 genera of the other tribes are not represented in the British Indian 

 Empire. 



I. Dipterocarpew. — Calyx tube enclosing the fruit; 2 lobes expanding into long wings. 

 Stamens more than 20 ; connective prolonged into a long point. Ovary with a large 

 fleshy stylopodium. 



Stipules large, amplexicaul, calyx tube free, stamens oo, 

 style filiform 1. Dipierocakpus. 



Stipules small, deciduous, calyx tube adnate to fruit, 



stamens 20-35, style short 2. Anisoptera. 



II. Shorecc. — Calyx as a rule imbricate in bud, in most cases the 2 or 3 outer segments 

 accrescent in fruit, forming long wings. Stamens mostly 15, rarely more (Shorea, 

 section Eushorea), in a few cases 10. Connective usually awned. 



Wings 2 ; appendix of connective long, pointed, as a rule 



a large stylopodium 3. Hopea. 



Wings 3 ; anthers with 5 pointed appendages . . 4. Pentacme. 



Wings 3 ; appendix of connective as a rule long, pointed 5. Shorea. 



Wings 5 ; calyx in bud nearly valvate ; anthers with 3 

 short appendages ........ 6. Parashorea. 



Lobes of fruiting calyx slightly and evenly enlarged, 

 thick, sometimes woody, appendage of connective long, 

 pointed. Stylopodium generally distinct . . .7. Balanocarpus. 



III. Vaticeaz. — Calyx valvate in bud. Stamens 15, anthers 



short, oval. Appendix of connective short, obtuse, 



no stylopodium 8. Vatica. 



IV. Vateriece.— Calyx imbricate in bud. Lobes of fruiting 



calyx equal and shorter than fruit. Stamens cc. 



Anthers linear-oblong with 1 or 2 appendages . . 9. "Vateria. 



