71 Diplazium xiphophyllum
. Three voucher spesimens of the three cytotypes diploid, tetraploid and hexaploid could not be made comparison because they
are in different stage of growth. However qualitatvely the three cytotypes are not different. Therefore it is presumed that they are autoploid.
Diplazium aequibasale, D. riparium and D. wahauense. Diplazium
aequibasale 2n=164, D. riparium 2n=82 and D. wahauense 2n=164 almost
have similar morphological appearances. Diplazium aequibasale have allied form between D. riparium and D. wahauense. D. wahauense is closely related to D.
riparium. Kato et.al. 1991 presumed that D. wahauense derived from D.
riparium which occurs in riparian and dryland forest in Borneo. The two species
share many character, viz. black, somewhat crisped, entire scales, blackish stipes, dark-brown, naked rachis, and imparipinnate leaves with 3-4 pairs of entire lateral
pinnae. D. wahauense differs from D. riparium mainly in its narrow pinnae, which are characteristic of rheophytes.
5.3.3. Relationship between ploidy level and habitat gradient
Although data are available for fern floras from different parts of the wolrd, there is not simple relationship between ploidy level and habitat Walker
1979. Some studies have revealed that lower-ploids occur in warmer habitats than higher-ploid, for example Lepisorus thunbergianus diploid vs. Tetraploid
Mitui et al 1987, Woodwardia orientalis diploid vs. tetraploid Mitui 1968, Dryopteris erythrosora
diploid vs triploid Hyrabayashi 1974, Pteris dispar diplaid vs tetraploid Nakato 1981, and Diplazium nipponicum triploid vs
tetraploid Takamiya et al 2000. However, many parts of Europe all three cytotypes 2x, 3x, 4x of the Polypodium vulgare complex were found in close
proximity Shivas 1961. Matsumoto 2003 did not find a significant relationship between latitude and ploidy level in the Cyrtomium falcatum complex. However
there was an association between ploidy level and habitat: diploid grew on sea cliffs or in dry forests, triploid grew at forest edges, and tetraploid grew in wet
forests. In the study of the Pteris fauriei complex in Taiwan, Huang et al. 2007 recorded any correlation between habitats, latitude, and elevation of P. fauriei.
72 The three parameters are related to temperatures. In general, triploid plants grow
in low temperature sites than diploid plants. In many species of Diplazium from West Malesia, however, there are not
any strick correlation between ploidy level and habitat gradient. All species with only diploid type, viz. D. accedens, D. petiolare, D. polypodioides, D, speciosum,
D. sorzogonense, D. spiniferum and D. umbrosum, are growing from 420 m to
1500 m. Species with two different ploidy levels are growing on almost the same elevation. The tetraploid D. crenatoserratum were collected from 20 – 150 m sea
level where the triploid one was also found in the range, 55 m sea level. Triploid and tetraploid D. angustipinna were found at the same altidude, 440 m. In
contrary, pentaploid D. batuayauense was growing at 440 m, whereas the tetraploid plant was found at 450 m. Overlap distribution was seen in D.
cordifolium . Tetraploid D. cordifolium was growing from 240 m to 1200 m,
whereas pentaploid plants were occuring from 1000 m to 1200 m. As has been mentioned above, there are only few species that has a correlation between ploidy
levels and habitat gradient, such is D. riparium and D. xiphophyllum. Some species of West Malesian Diplazium showed a correlation between
ploidy level and altitute gradient. Diploid D. riparium was found at 150 m, whereas the triploid plant was at 280 m. Tetraploid plants of D. pallidum were
only found above 1000 m, whereas those diploid were growing from 30 m to 250 m. Triploid and tetraploid D. silvaticum are growing at ca. 20 m and ca. 280 m,
respectively. The hexaploid D. xiphophyllum was found at higher altitude than those of tetraploid and diploid.
5.3.4. Correlations between reproductive mode and habitat
