The Systematics Of Cystopteris Bernh In China

In order to provide basis for determining the phylogenetic relationships among 9 species within Cystopteris Bernh., the morphology, leaf epidermal structures, scales, sporangia, cross section and palynology were investigated and compared under light microscope and scanning electron microscope. The results indicated that:1. Morphological comparisonGeneral morphology is similar, rhizomes horizontal creeping, leaf vein separable, sporangium round. But there are still many differences in the subtle aspects, including the rhizome length, leaf distance, leaf shape and the number of pinnae, as well as plant size, spore sac size etc. Consider these, in morphology, the relationship among C. fragilis, C. kansuana and C. dickieana are more closely; C. sudetica, C. pellucida, C. moupinensis, C. tibetica and C. deqinensis are close.C. montana has unique structural features.2. Leaf epidermisGeneral characteristics are relatively stable in different species, the upper epidermal cell is mainly long, anticlinal wall is in wave-dominated, cell size is stable, the ratio of length to width is basically similar, the lower epidermal cell and the anticlinal wall are given priority to irregular shape, but the stomatal apparatus type has obvious difference. C. fragilis, C. kansuana, C. pellucida, C. sudetica, C. tibetica and C. dickieana from xinjiang are based on anomoteracytic type, the others are taking axillocytic type as the dominant type.3. ScaleGeneral characteristics are basically similar in different species, scale is mostly brown, ovate to lanceolate, edge is smooth, with a small amount of projection or shorthair, mesh size is no significant difference, mostly long fusiform to rectangular. But there are still some differences in the scales shape and edge. C. fragilis, C. kansuana and C. dickieana from xinjiang and yunnan are lanceolate, edge with projections; C. dickieana from tibet is lanceolate, smooth; C. pellucida, C. sudetica and C. montana are ovate, smooth; C. tibetica, C. moupinensis and C. deqinensis are ovate, edge with projections.4. SporangiumThe general characteristics are basically similar, the sori borne back of leaf on each side along the costa, nearly circular, with indusium, sporangia with longitudinal band. The only difference is indusium shape, C. fragilis, C. kansuana and C. dickieana are ovate to lanceolate, the others are suborbiculate.5. Cross-sectionThe petiole base with 2 meristeles, nearly circular to elongate, was "八" shaped arrangement, xylem is typical "hippocampus type" or similar "hippocampus type", the differences of grooves and extent of constricted on both sides can not be ignored. By observation and comparison, the petiolar cross-section of C. dickieana from xinjiang and yunnan without obvious groove, the constriction of both sides is also unconspicuous, other species have obvious groove and constriction on both sides.6. SporeThe spores of Cystopteris are all monolete, bilaterally symmetric, ellipsoidal in polar view, kidney-shaped in equatorial view. But spores in different species have differences in spore size, ornamentation length and structure. According to the surface ornamentation of the perine, the spores in Cystopteris can be divided into three types. Type I is characterized by having echinate processes (or mostly echinate processes) on the perine:C. fragilis, C. kansuana, C. pellucida, C. tibetica, C. sudetica, C. moupinensis; Type II is characterized by having tuberculate processes on the perine:C. montana; Type III is characterized by having tuberculate processes on the perine:C. dickieana. The classification supports C. montana as an independent group. Having tuberculate processes on the perine is an obvious feature for distinguish C. dickieana.In summary, Cystopteris in china has closely interspecific relationship, but there are still some differences in morphological, anatomical, palynological. basic on those and take the content of cellular and molecular systematics predecessors accomplished as the reference, Cystopteris can be divided into four groups:the first group:C. fragilis, C. kansuana; the second group:C. Dickieana; the third group:C. pellucida, C. tibetica, C. sudetica, C. moupinensis, C. Deqinensis, in which C. pellucida, C. Sudetica and C. moupinensis have closer relationship; the forth group:C. montana. Also the C. dickieana from different area have some big differences in scales, stomatal type and spore forms.