Search

Pollen records from two sediment cores taken from Ilan Plain, northeastern Taiwan provide new insights into the environmental and cultural history of the last 4200 years. The record indicates a relatively warm climate at around 4200 cal b.p. The environmental conditions would have been suitable for people whose settlements and activities were mainly in the littoral zone during this period. However, at ca. 3800 cal b.p., elements tolerant of brackish water dominated the vegetation, indicating that the environment was influenced by marine incursion. The remarkable increase in wetland flora suggests the presence of widespread marshlands thereafter. It is quite conceivable that settlement movement from the fluvial plain to hills between 3800 and 2400 cal b.p. can be correlated with the environmental changes in lowlands. A conspicuous gap in the archaeological sequence between 2400 and 1300 cal b.p. corresponds chronologically with a period of heavy rainfall or frequent typhoons as indicated by the aggradational episode in the Lanyang drainage basin as well as the flourishing of Alnus forests. The persistence of frequent landslides and climate deterioration would have had a dramatic impact on ancient humans and led to abandonment of the settlements. By 1300 cal b.p. a lowland flora is widespread indicating a shift from a marsh to a terrestrial environment in response to a well-developed fluvial plain. Decrease of landslides and the amelioration in climate could have advantages to human activities again. However, both the pollen and archaeological records indicate that intensive colonisation had a profound effect upon the vegetation within the Ilan region about 400 years ago.

Species delineation in Euphrasia has long been a challenge for taxonomists. In this paper, DNA sequences are used to evaluate the morphological taxa of Taiwanese Euphrasia as well as to elucidate the phylogenetic relationship among them. ITS sequences of 147 samples of Euphrasia, one Aeginetia, and one Pedicularis from Taiwan along with nine samples of Euphrasia from abroad were studied. Six non-native species of Section Euphrasia were used as outgroups and 14 haplotypes from four taxa of Taiwanese Euphrasia, E. tarokoana Ohwi, E. nankotaizanensis Yamam., E. transmorrisonensis Hayata, and E. transmorrisonensis var. durietziana (Ohwi) T. C. Huang & M. J. Wu, served as the ingroup to reconstruct a phylogenetic tree according to the criterion of maximum parsimony. Based on the phylogenetic tree, three monophyletic haplotype lineages of the ingroup were obtained, closely correlating with geographical distributions (with some overlap in adjacent regions). However, plants of different taxa are found in the same lineage. Lineage I includes all four Taiwanese taxa, whereas lineage II includes two taxa, E. transmorrisonensis, and E. transmorrisonensis var. durietziana. Lineage III includes three taxa: E. nankotaizanensis, E. transmorrisonensis, and E. transmorrisonensis var. durietziana. Different taxa share a common haplotype. Euphrasia nankotaizanensis, E. transmorrisonensis, and E. transmorrisonensis var. durietziana share haplotype E; E. nankotaizanensis and E. transmorrisonensis share haplotype D; and E. transmorrisonensis and E. transmorrisonensis var. durietziana share haplotypes G and N. The shared haplotypes may reflect retained ancestral polymorphisms at a neutral locus (ITS) through a series of recent speciation events (lineage sorting). The nucleotide additivities are found frequently among taxa. For example, the A+B additivity pattern of E. tarokoana and E. transmorrisonensis var. durietziana could reflect hybridization. Nucleotide additivity also provided insight into reticulate relationships among populations within and between taxa. Lineage sorting and hybridization might be mechanisms driving speciation in Taiwanese Euphrasia, resulting in retention of morphology and adaptation to distinct habitats. According to ITS evidence, we reconfirm four taxa of Euphrasia in Taiwan.

This paper intends to elucidate the anther wall development, pollen wall development and exine substructure of Uraria crinita (L.) Desv. ex DC. (Fabaceae). The undifferentiated anther is ovoid-shaped and tetrasporangiated. The anther wall development is basic type, which is comprised of an epidermis, an endothecium layer, two middle layers and a tapetum. Anther-tapetum is glandular type and the cells are uniseriate and uninucleate. Pollen grains are tricolporate and 2-celled at the time of shedding. Before protectum development begins, a glycocalyx layer is inserted against the callose, and the plasma membrane is invaginated, exclusive of the future apertures. Subsequently, the probacula are elongate under the protectum and arise basally from the plasma membrane. The foot layer and endexine formation are concomitant with the callosic wall dissolution. The foot layer is thin and interrupted, but the endexine is thick and continuous. The intine is initially in the vacuoled stage. The substructure in the tec...

The pollen of 15 species of Indigofera from Taiwan was studied by means of light microscopy, scanning electron and transmission electron microscopy. The pollen of these species is classified into five types on the basis of exine structure, perforations, shape of tectum channels, granular or columellate interstitium, and prominent or reduced foot layer. Subdivisions of each type are based on the ornamentation of the tectate surface on the apocolpia and the mesocolpia. It is suggested that Type I is the most primitive and that Type II has evolved from it. Type II has undergone a multiplication of granules, an elaboration of the tectum and a reduction of foot layer to form the most complex Type III. Type II has also evolved towards a modification of the columellae to form the lamellate interstitium of Type IV. Through a reduction of the lamellate granular layer of Type IV the single granular layer of Type V has formed. It is also possible that Type 1.3 has undergone a reduction of the columellae to ...

Isoetes contains approximately 150 species (Tryon & Tryon, 1982). Plants are diverse in habitat, ranging from evergreen hydrophytes to deciduous xerophytes (Pfeiffer, 1922). In Taiwan, I. taiwanensis DeVol grows submersed, but becomes emergent during short dry seasons. There are accounts of Isoetes plants being eaten by fish, birds, pigs, ducks, muskrats, cattle and humans (Pfeiffer, 1922), but in Taiwan, only ducks or other migratory birds are known to eat Isoetes (Chang & Hsu, 1977). In 1971, K. S. Hsu and H. C. Chang collected I. taiwanensis in Dream Lake, in the vicinity of Taipei's Yang Ming Shan National Park, at an altitude of 700m. Eight papers concerning this discovery have been published since 1972 (DeVol, 1972a, b, 1975; Chang & Hsu, 1977; T. C. Huang, 1981; S. E Huang, 1982; Huang & Chen, 1988). As part of a study on I. taiwanensis, spores were examined using a scanning electron microscope. Spores of three geographically proximate Isoetes species were also studied for comparison. A strategraphic pollen analysis was also made in Dream Lake sediments to determine the time of appearance of I. taiwanensis. MATERIALS AND METHODS

Ten genera and seventeen species of Apocynaceae from Taiwan were studied by means of transmission electron microscopy. Five types of exine stratification are recognized based on ultrastructural features and apparent chemical characteristics. In type I, the nexine corresponds to a foot layer plus the endexine; in type II, the nexine corresponds directly to the foot layer only; in type III, the nexine corresponds directly to the endexine only; in type IV, the nexine is absent and the infratectal stratum is a granular layer and in type V, the nexine is also absent, but the infratectal stratum is a reticular layer at upper and lower portions underlain by a granular layer in the middle with granules of varying size and shape. Except for the species of Trachelospermum, the rest of the infrageneric taxa can be keyed out by palynological characters. Possible evolutionary trends in exine stratification are proposed.

The results of daily collection of atmospheric pollen grains and spores in Taipei, Taiwan during June 1974 and May 1975 are presented. A total of 26307 grains belonging to more than 62 taxa were obtained. Most were of short distance dispersion. The results show that 56% were tree pollen grains with over 38 taxa, 22.7% grass pollen grains, 10.2% fern spores with over 13 taxa, 9.1 % weed pollen grains with over 10 taxa, and 2% unidentified taxa. Of the annual count, 20.7% were collected in the summer and were dominated by fern spores. In the autumn 26.3 % were collected and were dominated by grasses. In the winter, 4.4% was collected and in the spring, 48.6% with trees dominating. The relationships between pollen occurrence and meteorological factors is also discussed.