16 of D. esculentum have poorly developed intercellular spaces of rheophytes Kato
Imaichi unpublished, there is no distinct morphological difference between the reophytic and dryland plants. Kato 1991 regarded such species as evolutionarily
incipient rheophytes. Kato et al 1991 assumed that most rheophytes are products of primary
speciation from dryland mother species. Diplazium wahauense presumably derived from D. riparium, Deparia biserialis and De. confluens from D.
petersenii, Phronephrium hosei from P. rhombeum or P. menisciicarpon.
2.3.1.2. Riparian Diplazium
Only few species occur on river banks or stream. They are D. aequibasale
, D. riparium, D. fuliginosum, D. lomariaceum and D. porphyrorachis Table 2.2.. However these species do not strictly grow at this habitat. The last
three species are more usual growing in dryland of shady ravine in the forest. In Borneo, much of individual plants of D. riparium are also growing well in shady
dryland. All species mentioned above, are usually found on lowland mountain forest.
Environmental condition seems very important component of speciation in Diplazium
although this of course depend upon of how one of species response the ecological change. Diplazium riparium and its closely related species D.
aequibasale and D. wahauense may be a good example for it. Kato et al 1991
presumed that D. wahauense may have been derived from D. riparium which occurs in riparian and dryland forest of Borneo. As they explained and supported
by this studies see Chapter 8, these two species share black scales, somewhat crisped, entire scales, blackish stipes, dark brown, naked rachises, and
imparipinnate leaves with 4 pairs of entire lateral pinnae. Diplazium wahauense differs from D. riparium mainly in its narrow pinnae, which are characteristic of
rheophytes.
2.3.1.3. Diplazium in Dryland
Most of Diplazium species are growing terrestrially in dryland forest. Table 2.1. and 2.2.. According to the light intensity, the dryland Diplazium can
17 be divided into three groups: a opened area, b light shady ferns, and c deep
shady ferns. The species that adapted to the light intensity are discussed below. a. Opened area ferns
D. esculentum usually grows on opened areas. This species grows well at
the dump soil of opened areas both in the forest and at the farming areas. Therefore sometimes this species often form small population at the edges of
rivers or stream. b. Light shady ferns
There are great number of species growing in the light shady area. Some species adapted to very humid conditions and living near streams, such as D.
accedens , D. kunstlerii, D. procumbens, D. profluens, D. squarrosum, D.
spiniferum, and D. vestitum. The humidity of the air in primary forest near
streams is always high, even in the places well away from streams its average is much above that of the open air outsite the forest.
Many species are growing well on dry areas, tolerating drier soil and air. They are found further from streams on forested hill slopes, viz. D.
asymmetricum; D. atrosquamosum D. bantamense, D. barbatum, D. batuayauense, D. betimusense, D. cordifolium, D. crenatoserratum, D.
densisquamatum, D. dilatatum, D. dolichosorum, D. donianum , D. fraxinifolium, D. halimunense, D. hewittii, D. hottae, D. latisquamatum, D. lobbianum, D.
loerzingii, D. malaccense, D. megasegmentum, D . meijerii, D. pallidum, D. parallelivenium, D. petiolare, D. poiense, D. polypodioides, D. sorzogonense, D.
speciosum, and D. simplicivenium.
Shady ferns usually grow more slowly than sun-ferns. The weak light prevents plants to make its carbohydrates fast and the high humidity may make
less loss of water and less root activity. However this condition does not prevent many species of Diplazium from attaining a immense size, such as D. accedens,
D. dilatatum, D. polypodioides, D. subpolypodioides, D. megasegmentum , and D.
sorzogonense.
18 Table 2.1. Classification of Diplazium Based on their main habitat
Major Group
Species Number of
Species Rheophytic
D. aequibasale, D. wahauense 2
Riparian D. aequibasale
, D. riparium, D. fuliginosum, D. lomariaceum, D. porphyrorachis
5 Dryland
D. accedens , D. albidosquamatum, D. angustipinna, D.
asymmetricum , D. atrosquamosum, D. bantamense, D. barbatum,
D. batuayauense , D. beamanii, D. betimusense, D. christii , D.
cordifolium , D. crameri, D. crenatoserratum, D. crinitum, D.
cumingii D. densisquamatum , D. dilatatum, D. dolichosorum, D.
donianum , D. esculentum , D. fraxinifolium, D. halimunense, D.
hewittii , D. hottae, D. insigne, D. kunstlerii, D. laevipes, D.
latisquamatum , D. lobbianum, D. loerzingii, D. malaccense, D.
megasegmentum , D. megasimplicifolium, D. melanolepis, D.
meijerii , D. moultonii, D. pallidum, D. parallelivenium, D.
petiolare , D. poiense, D. polypodioides, D. prescottianum, D.
procumbens , D. profluens, D. riparium, D. silvaticum, D.
simplicivenium , D. sorzogonense, D. speciosum, D. spiniferum, D.
squarrasum , D. subintegrum, D. subalternisegmentum, D.
subserratum , D. subvirescens, D. tomentosum, D. tricholepis, D.
umbrosum , D. velutinum, D. vestitum, D. xiphophyllum
64
c. Deep shady ferns. Many species are adapted to deep shady areas, such as D.
albidosquamatum, D. angustipinna, D. beamanii, D. christii , D. cumingii, D.
fuliginosum, D. laevipes, D. lomariaceum, D. moultonii, D. poiense, D. tomentsum,
and D. umbrosum. Therefore they are nearly all have much thinner fronds than the light shady ferns. The deep shady ferns species do not need to be
tough to avoid being shriveled by the sun’s heat. These species do not need to store water as much as some light shade ferns do. The deep shady ferns usually
also show more dark green or blue metallic fronds than the light shade ferns Figure 2.1..
This classification is not strict as some species are also grow well in opened and light shady areas. D. polypodioides are seen in the gap areas of thick
forest and also in the margin forest. There are several species found growing in both light shady and deep shady areas. D. bantamense, D. batuayauense, D.
cordifolium , D. crinitum, D. crameri, D. dilatatum, D. donianum, D.
fraxinifolium, D. lobbianum, D. loerzingii, D. malaccense, D. melanolepis, D.
riparium, and D. sorzogonense can be found in light shady and deep shady areas.
19
2.3.2. Diversity of Diplazium Based on Elevation
