716 



NATURALIST'S GUIDE TO THE AMERICAS 



unacquainted with tropical forests. 

 Climbing aroids also attract attention. 

 Several species of Rhaphidophora, with 

 large, often deeply-lobed leaves, are 

 among the most remarkable of these. 

 Pothoidium and Pothos are aroids which 

 cling to the trunks of trees by means of 

 horizontal adventitious roots. They 

 have linear leaves that stand _ at right 

 angles to the stem; the leaf is joined near 

 the middle, the distal portion being the 

 blade and the proximal portion an ex- 

 panded leaf base, having the photosyn- 

 thetic function. Large climbing ferns of 

 the genus Stenochlaena are also con- 

 spicuous on exposed tree trunks. Dicot- 

 yledonous vines form a very prominent 

 part of the vegetation. They attain 

 great lengths, and hang suspended like 

 long ropes from the branches of the high 

 trees. These vines resemble somewhat 

 the grapevines of the woods of the 

 eastern United States, but differ in their 

 greater size and abundance and in the 

 fact that many of them are twiners. 

 A number of stems will often be twisted 

 tightly together, forming a spirally- 

 twisted, rope-like mass. Among the 

 most characteristic of the larger vines 

 are Symphorema luzonicum (Blanco) F. 

 Vill. belonging to the Verbenaceae, and 

 several species of the genus Mucuna, of 

 the family Leguminosae, including vines 

 that bear purple or white evil-smelling 

 flowers, whose calyxes and young pods 

 are covered with extremely irritating 

 spines. Strongylodon macrobotrys A. 

 Gray, also of the Leguminosae, which 

 has greenish-blue flowers on large 

 panicles one meter long, is frequently 

 found in moist places. Among the other 

 vines that may be mentioned are several 

 species of Tetrastigma and Cisus of the 

 Vitaceae, Bauhinia cumingiana (Benth.) 

 F. Vill. of the Leguminosae, Uvaria 

 scandens C. B. Rob, and other species of 

 Uvaria of the Anonaceae, and Merremia 

 nymphaeifolia (Blume) Hallier of the 

 Convolvulaceae. 



Epiphytes are not so prominent in the 

 High Forest as in the other two zones. 

 But a number of kinds may be seen on 

 the horizontal branches and in the forks 

 of the trees. Among these epiphytes 

 are several species of ferns; probably 

 the most numerous are Drynaria querci- 

 folia L. Sm. and Asplenium nidus L., 

 the bird's nest fern. The former has 

 leaves of two sorts; one is the ordinary 

 foliage leaf, and the other is a scale that 

 collects decaying leaves. Roots pene- 

 trate this mass of decaying matter and 

 apparently absorb water and other 

 substances from it. Orchids of many 

 species occur as epiphytes in this forest ; 

 but they are relatively scarce, and most 



of them do not have either conspicuous or 

 beautiful flowers. The orchid with 

 showy flowers that is most frequently 

 collected is Phalaenopsis amabilis Blume, 

 the butterfly orchid, which has green 

 leaves and large white flowers. 



A grotesque member of the flora of 

 Mount Makiling is Rafflesia manillana 

 Teschem. This is found usually in the 

 transition zone, in passing from the High 

 Forest into the Rain Forest, although it 

 also occurs in the High Forest. The 

 mature plant of Rafflesia consists prin- 

 cipally of a reddish-brown flower, from 

 fifteen to twenty centimeters in diame- 

 ter, found growing as a parasite on the 

 root of Cissus, a vine. The morphology 

 of Rafflesia manillana Tesche M. has 

 been carefully studied by Brown. 6 

 The root of Cissus upon which the plant 

 grows often bears a number of young 

 buds in addition to a series of mature, 

 open flowers. Five or six specimens 

 may sometimes be found growing near 

 the surface of the soil in a very small 

 area. There is usually no difficulty in 

 locating specimens of Rafflesia, some 

 being found within a meter of the trail. 



Another strange plant is Taeniophyl- 

 lum, an epiphytic orchid that has flat, 

 green roots, about 3 mm. wide and 30 

 cm. long. The stem and leaves of this 

 orchid are very much reduced, and the 

 photosynthetic process takes place in 

 the root. This is a case of an extreme 

 modification of the root. A number of 

 orchids, of course, contain chlorophyll in 

 long cylindrical roots; but this^ orchid 

 performs all of its photosynthetic work 

 in these long, flat, leaf-like roots. 



The mammals of the High Forest are 

 for the most part also found in the grass- 

 land and parang occasionally, and have 

 already been mentioned the Philippine 

 deer, Rusa philippinus Smith; wild 

 pigs, Sus philippinensis Nehring; mon- 

 keys, Macacus cymologus var. cummingii 

 Gray and the alemoose or civet cat, 

 Viverra tangalunga Gray. There are 

 several conspicuous birds found in this 

 and in the rain forest, which seldom if 

 ever leave the dense forest cover. The 

 noisy great hornbill or calao, Hydrocorax 

 hydrocorax L., with its red head and bill, 

 and black and brown plumage, noisy 

 flight and raucous call of "Au, calao, 

 au, au" demands attention, as does its 



s Brown, W. H. The relation of Rafflesia manil- 

 lana to its host. Philippine Journ. Sci., Sec. C, 7: 

 209-226. pis. 10. 1912. 



