Table of Contents

10 May 1997, Volume 35 Issue 3
    Research Articles
  • Lu Bao-rong
    J Syst Evol. 1997, 35(3): 193-207.
    Elymus L. and Hordeum L. are the two largest genera in the wheat tribe (Triticeae Dum. ). The former comprises approximately 150 perennial and exclusively polyploid species and the latter encompasses about 40 perennial or annual taxa with different ploidy levels. Both of the genera are widely distributed in the temperate regions all over the world.Owing to the fact of a large number of species in each genus, wide geographic distribution,various ecological habitats, and a great variation in morphology between and within species, the taxonomy at species level in the two genera, particularly in the genus Elymus, becomes extremely difficult. Based mainly on the morphological studies, the traditional taxonomists concluded that the two genera possessed comparatively distant biosystematic relationships. However, the data based on the cytological studies have shown that the H genome in Elymus has its origin from species in Hordeum. In order to shed light on the biosystematic relationships between the two genera, the present author conducted intergeneric hybridization between species in Elymus and Hordeum with different origins. Chromosome pairing behavior was observed and analyzed at metaphase I of meiosis in the parental species and their intergeneric hybrids. It was shown from the present study that comparatively high crossability occurred between species in the two genera when Elymus species were used as female, and that the hybrid plants could be easily obtained with the add of embryo culture techniques.The morphology of the intergeneric hybrids, which were generally weaker and smaller than the parents, was intermediate between the two parents, but more closely resembled that of the female parents, i.e., Elymus. The reproductive organs of the intergeneric hybrids developed incompletely in some hybrid combinations and abnormally in all hybrids with non-dehiscent anthers. All the hybrid plants were completely sterile. The results from cytological observation showed relatively low chromosome pairing at metaphase I of all the F1 hybrids, albeit with a large variation between different combinations. It is concluded from the present experimental data together with some other morphological and cytological observations obtained previously that the biosystematic relationships between the two genera Elymus and Hordeum is very complicated and can not be generalized in a simple way. Species which share the H genome in the two genera have comparatively close biosystematic relationships, but the H genomes in different species of the two genera have more or less differentiated during the evolutionary process. Species which do not contain the H genome in the two genera have rather distant phylogenetic relationships.
  • Li Ming-wang, Gu De-xing, Liu You-liang, Hsu Ping-sheng
    J Syst Evol. 1997, 35(3): 208-214.
    By examining the somatic chromosome numbers and average numbers of bulbils per leaf of 10 populations belonging to 5 species of Pinellia, 5 chromosome numbers (P.peltata Pei 2n = 78, P. cordata N. E. Brown 2n= 72, P. ternata (Thunb.) Breit. 2n= 54,99,108) new to this genus are reported. The present work also shows that the species with x= 13 including P. yaoluopingensis X. H. Guo et X. L. Liu (popullation Ⅰ ~ Ⅲ ), P. tripartita (Blume) Schott (previous reports), P. pedatisecta Schott (population Ⅳ)and P. peltata (population Ⅴ )have no bulbils at all,while those with x= 9 including P. cordata (population Ⅵ ) and P. ternata (population Ⅶ ~ Ⅹ )have bulbils more or less depending on their ploidy-the average number of bulbils per leaf of hexaploid (population Ⅶ ) is only 0. 043,which is much lower than 1.95 of that of dodecaploids (population Ⅹ ). Based on these observations, it could be supposed that polyploidy reinforce apomixis, the diploid ancestors of P.ternata have no bulbils and in Pinellia, x= 13 may be more primitive than x = 9. The chromosome counts of the Araceae are changeable and complex, but appear to be explainable on the dual basis of ascending and descending dysploidy at secondary (paleopolyploid)level from a primitive basic number x = 7. P. ternata is a polyploid complex and probably it came from a diploid ancestors without bulbils and with x = 7,8,9, etc. The basic chromosome numbers x=7,8,9 of Pinellia ternata may have been derived from x= 13 of P. yaoluopingensis by descending dysploidy in the early stage of the evolution of this genus. Then, as a result of secondary polyploidy, bulbils which enable the species to adapt to its varied environments occur and they might lead to a more rapid evolution in this species.
  • Xiong Zhi-ting, Chen Sing-chi, Hong De-yuan
    J Syst Evol. 1997, 35(3): 215-218.
    Disagreement exists among research workers in regard to the taxonomic relationship among three Chinese endemic species of Hemerocallis : H. plicata , H. forrestii and H. multiflora. The present authors attempt to resolve this problem based on a study on karyotypes. The karyotype formulas of H. plicata, H. forrestii and H. multiflora are respectively 2n = 12m + 8sm + 2T, 2n = 8m + 12sm + 2T and 2n = 12m + 4sm + 4st + 2T, in which the T chromosomes (No 11 ) of all the three species have microsatellites at the centromeric end. The Euclidean distances of chromosome complements are 0. 2728 between H. plicata and H.forrestii ,0. 4501 between H. plicata and H. multiflora and 0. 5741 between H. forrestii and H. multiflora. These data clearly indicate that H. plicata is more closely related to H. forrestii than to H. multiflora, and that H. multiflora is more advanced thanthe other two species,for the karyotype of H. multiflora is more asymmetical.
  • Ren Yi, Hu Zheng-hai, Li Zhi-jun
    J Syst Evol. 1997, 35(3): 219-224.
    Observations on the dichotomous leaf venation of Circaeaster agrestis found no intermediate forms of the fusion of vascular bundles between the two completely fused commissural veins of anastomoses and the two separate approximate veins, but found different degrees of the vestige of commissural veins . The fact indicates the impossibility of the formation of anastomoses from approximate veins. The occurrence of blind veins is related to the degeneration of teeth, the interruption of the commissural veins and the interruption of nonanastomosous veins at the branching point. Therefore, we considered the dichotomous leaf venation of this species as a reduced characteristic.
  • Wang Qing-feng, Zhang Zhi-yun, Chen Jia-kuan
    J Syst Evol. 1997, 35(3): 225-235.
    Pollen morphology of 27 species representing 11 genera of the Alismataceae was studied by light microscope (LM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Based on the observed pollen characters, three types of pollen were distinguished: (A) The Caldesia-oligococca type. Disc- or lens-shaped, with 2 pores (pores probably equatorially orientated, opposite each other); pores situated in depressions, more or less circular with fimbriate, fold-like structures arising from the margins; the exine granulate or slightly spinulate under SEM. (B) The Sagittaria type. Spheroidal, pantopo rate; pores in hardly sunken depression, delimited or not sharply delimited in outline, covered with coarsly or sparesly granulate or spinulate membranes; the exine spinulate with spinules 1~2 μm long. (C) The Alisma type. Rounded to polyhedral pantoporate; pores covered with granular membranes and circumpolar ornamented area, situated in depressions; the exine smooth to finely spinulate with spinules less than 0.5 μm long. The exine structure of all examined materials under TEM is three-layered: tectum, columellae and footlayer. The endexine is neither distinguished nor separated from the footlayer. The most primitive alismataceous pollen grains might be boat-shaped, monosulcate, with hardly sunkenpores, smooth pore membranes and exine spinulate exine without tectum perforation. The pollen of the Alismataceae is most likely derived from the monosulcate ancestor (possibly via nonaperturate intermediate) by an increase in pore number and a reduction in supratectal ornamentation. The evolutionary trends of alismataceous pollen are described as follows: (A) Pollen shape: from boat-shaped type to polyhedral one via a spherical intermediate condition, then to bilateral pollen, the highly derived. (B) Aperture: from the primitive monosulcate type to the pantoporate one via a nonaperturate condiation. (C) Aperture membrane: from smooth to granulate and spinulate. (D) Aperture not sunken was primitive; while sunken condition derived. (E) The sculpture of exine: from spinulate to granulate or spinuleless. (F) Tectum with microchannels or channels might be derived, that without channels the most primitive.
  • Jiang Ze-ping, Wang Huo-ran
    J Syst Evol. 1997, 35(3): 236-248.
    Cupressaceae and Taxodiaceae have recently been merged under the earlier name Cupressaceae s.I. by many authors, as the two families are similar in a number of morpho logical characters. Sciadopitys S. et Z., which has often been treated as a morphologically isolated member of the Taxodiaceae, has recently been considered as a monotypic family, Sciadopityaceae. The Cupressaceae s.s. may be reorganized into two subfamilies. The Cu pressoideae is composed of genera with the uppermost cone-scales infertile and can be divided into four tribes: Cnpresseae, including Cupressus, X Cupressocyparis, Charnaecyparis and Fokeinia;Thujopsideae, including Thuja, Thujopsis and Platycladusl Junipereae, including Juniperus and Microbiota; and Tetraclineae, including Calocedrus and Tetraclinis. The Callitroideae is composed of genera with the uppermost cone-scales fertile and can be divided into three tribes: Actinostrobeae, including Actinostrobus, Callitris, Fitzroya and Neocallitropsis; Widdringtoneae, including Pilgerodendron, Diselma and Widdringtonia ; Libocedreae, including Libocedrus, Papuacedrus and Austrocedrus. Five geographical distribution patterns are recognized in the 21 genera of Cupressaceae. (a) One genus, X Cupressocyparis, is a natural hybrid derived from selections in England; (b) Two genera, Cupressus and Juniperus, are distributed in Africa, Europe, Asia and North America; (c) Three genera, Thuja, Chamaecyparis, and Calocedrus, are disjnnctly distributed in Eastem Asia and North America; (d) Five genera, Actinostrobus, Callitris, Libocedrus, Papuacedrus and Widdringtonia, have limited distribution; and (e) The other 10 genera, which are monotypic, are restricted to narrow areas except Plotycladus. Three centers of genera diversity are identified in the Cupressaceae, i. e Eastern Asia with nine genera, southwestern North America with five genera, and Australia and its adjacent islands in the east with six genera, including New Zealand,. Tasmania, New Caledonia, and New Guinea. Other important areas are western Mediterranean with three genera and Chile and Argentinawith three genera.
  • He Chao-xing, Tao Jun-rong
    J Syst Evol. 1997, 35(3): 249-256.
    This paper reports the fossil flora in the Yilan Coal Mine, Heilongjiang Province.The Paleogene flora of the Dalianhe formation includes two groups according to their geology column:one (flora A) is from sand-shale above the lower coal seams and the other (flora B) is from oil shale above the upper coal beds. The flora contains two species of pteridophytes, 10 species of gymnosperms and over 40 species of angiosperms including 1 new species and 10 uncertain species, assigned to 49 genera and 35 families. The analysis of the floristic composition and their foliar physiognomy showes that the flora A consists of elements in evergreen broad-leaved and deciduous broad-leaved forests indicating its subtropical feature, whereas the flora B consists of elements in deciduous broad-leaved forests indicating a warm-temperate feature. Compared to the Paleogene floras of Northeastern Asia and North America, the flora A is assigned to the early Eocene, and the flora B to the late Eocene. These results seem to indicate that in the Eocene, paleoclimatic decline took place in Northeast China.
  • Xia Yong-mei
    J Syst Evol. 1997, 35(3): 259-261.
  • Zhang Ding-cheng, Zhang Chun-yang, Shao Jian-zhang
    J Syst Evol. 1997, 35(3): 265-267.
  • Feng Bao-yuan, Xie Si-min
    J Syst Evol. 1997, 35(3): 268-268.
  • Shi Zhi-xin
    J Syst Evol. 1997, 35(3): 269-272.
  • Guo Yu-qing, Xie Shu-qi, Li Jiang-song
    J Syst Evol. 1997, 35(3): 273-274.
  • Sun Qi-gao, Song Shu-yin, Wang Yu-fei, Li Cheng-sen
    J Syst Evol. 1997, 35(3): 275-288.
    The terminology of classification of dicotyledonous leaf architecture is introduced in Chinese version. It is very useful for the standardization of terminology and academic communication.