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E.S. Fernando: Vegetation of the Philip~ine Islands 8
Some of the more common woody dicots on Mt Sialdang subalpine rain forest include Slyphelia
suaveolens, Rhododenrun quadrassianum, Vaccinium myrtoides, Mylica javanica,
Leptospermum flavescens, and Eurya coriacea (Mandia 1994). This assemblage of plants fits
well with the subalpine formation on the rocky summits of Mt Kinabalu (4101 m alt., Borneo)
and Mt Kerinci (3800 alt., Sumatra).
Diversity and Endernisrn
Our knowledge of the flowering plants of the Philippine Islands is still sketchy and the present
account is inevitably incomplete. Merrill's work of 1923-1926 remains the most useful, but
obviously needs revision and updating.
The Philippine flora is a rich one comparable to those of other areas in the tropics (Fig. 4). This
richness is, in part, due to the composite origin of the archipelago with its floristic elements of
different sources now mixed together. The archipelagic character and mountainous topography
of the islands likewise, could have providedflowering plants with diverse habitats and a broader
range of ecological opportunities, thus enhancing adaptive radiation.
The indigenous flowering plants are estimated at about 8000 species belonging to nearly 1500
genera and 200 families. These estimates are based from Merrill (1926). The number of
species is roughly 26%-32% of the 25 000-30 000 (Jacobs 1974) estimated for the entire
Malesian region, while the number of genera represent more than 60% of the total 2382
(Steenis 1987) for the region.
About 37% of the estimated number of species are trees with a stem diameter of 3 crn or more
(Salvosa 1963). Indeed, its tree flora is particularly diverse (Table 2).
Of the genera only 23 are now considered endemic or approximately 1.5% of the total (Table
3). This is about 10.5% of the total number of endemic genera (218) for the whole of Malesia.
The Philippine endemic genera include representatives of 12 families. There are four in
Rubiaceae; three each in Asclepiadaceae and Orchidaceae; two each in Melastomataceae,
Sapindaceae, Zingiberaceae and Loranthaceae; and one each in Urticaceae, Leguminosae,
Euphorbiaceae, Rutaceae and Compositae.
Endemism at the species level is relatively high, reaching 70% to 80% in certain families,
especially those inhabiting primary forests (Merrill 1926; Dickerson 1928). These include,
among others, the following, each with no less than 15 genera: Orchidaceae, Rubiaceae,
Euphorbiaceae, Sapindaceae, Asclepiadaceae. Palmae, Annonaceae, Meliaceae,
Zingiberaceae, Sterculiaceae, Melastomataceae and Verbenaceae (Mitra 1973). The
Orchidaceae, with nearly 900 species and 77 genera, is the largest family of flowering plants in
the Philippines. In the Palmae with 135 species and 20 genera, species endemism reaches
over 70% (Fernando 1990). In Symplocos (Symplocaceae) endernism is 77% (Nooteboom
1977), while in Rhododendron (Ericaceae) it is 72% (Sleumer 1966). In other families of mostly
woody large trees, endemism is slightly lower, e.g. Dipterocarpaceae, 47% (Ashton 1982),
Fagaceae, 31 % (Soepadmo 1976), Burseraceae, 33% (Leenhouts 1956) and Anacardiaceae,
44% (Ding Hou 1978). However, on the whole, species endemism is estimated at about 75%
(Merrill 1 926; Dickerson 1 928; Mitra 1 973).