The Philippine journal of science. [Vol. 67, no. 1]

274

The Philippine Journal of Science

1933

chyma layers as in Anisoptera and some species of Shorea.
The inside of the bark is usually yellow and darkens on exposure
to the air. There is often a pale greenish or olive line at the
junction of wood and bark.
The species of this genus are usually trees of medium or
large size, although they do not reach the proportions of the
large species of Dipterocarpus and Shorea, and their boles show
a greater amount of taper.
Flowering and fruiting.-None of our species are known to
have a regular fruiting period, although it is believed that
all, or nearly all, fruit at tolerably frequent intervals. Fruiting appears to be local rather than general.
Distribution.-The members of this genus are much less
abundant than some of the species of Dipterocarpus and Shorea, and have a more scattered occurrence. They may be
gregarious to the extent of small groups at rather large intervals. None of the species are found very high in the mountains,
although certain forms are common on ridges below 800 meters.
Some species are characteristically found on low flat ground
or along streams.
The genus comprises about 60 species, distributed throughout
most of the range of the family, about as follows: Ceylon 3;
India 5; Burma 4; Siam 5; Indo-China 5; Malay Peninsula 16;
Sumatra 9; Java 2; Borneo 19; Celebes 1; Philippines 7. All
the Philippine species are endemic.
Key to the Philippine species of Hopea.
a 1 Secondary nerves few and prominent.
b. Leaves oblong, unilaterally unsymmetrical.
c1. Leaves 10 to 15 cm long, 2.2 to 7 cm wide; fruiting calyx lobes
less than 8 cm long.
dl. Stipules long, semipersistent; calyx wings 6 to 7.5 cm long.
2. H. philippinensis.
d. Stipules short; calyx wings 3.5 to 4.3 cm long.... 1. H. basilanica.
c 2. Leaves more than 15 cm long; calyx wings 8 cm long or longer.
3. H. mindanensis.
b a. Leaves ovate or lanceolate.
cl. Leaves long-acuminate, without domatia................ 5. H. acuminata.
ca. Leaves not long-acuminate; domatia prominent........ 4. H. plagata.
a '. Secondary nerves numerous, close, indistinct, almost parallel. ~ Dryobalanoides.
b h. Leaves elliptic, cuneate at base, 8 to 12 cm long; fruit wings 4 to
5.5 cm long..................................................... 6. H. malibato.
b'. Leaves and fruit smaller...................................... 7. H. Foxworthyi.