Studies on the Karyotype and Systematic Position of Larix Mill. (Pinaceae)

The present paper reports the karyotype of Larix potaninii Batal. endemic to China, and discuss classification of Larix and its systematic position in the Pinaceae based on karyotype and other data. The karyotypic formula of the species is K(2n)=24= 12m+ 8sm+4st, which belongs to Stebbins’2A type and the chromosome complement of relative length is 2n=24=4L+8M₂+8M₁+4S. The karyotype of the genus Larix (10 species) is composed of six pairs of longer metacentric chromosomes and six pairs of shorter submetacentric or subtelocentric chromosomes with arm ratio>2. This karyotype is an advanced one. It seems that Sect. Multiserales is more advanced than Sect. Larix. On the basis of the comparison among the karyotypes of pinaceous genera, the author finds that Larix and Pseudotsuga are much more closely related to each other than any of them to the others. Therefore, it may be more appropriate to group these two genera into Subfamily Laricoideae, which is a more advanced one. The conclusion is also supported by the data from morphology, anatomy, palynology,biochemistry, palaeobotany and so on.     

Two Evolutionary Lines of Taxodiaceae

According to the karyotypic data the present author proposes two evolutionary lines, A and L (Fig. 1), in Taxodiaceae (Exclud. Sciadopitys). The former is characterized by a relatively rapid increase of the mean arm ratio but a relatively slow rise of the ratio of the longest chromosome to the shortest one and it is composed of Cryptomeria, Glyptostrobus, Taxodium and Taiwania, which advance from primitive to progressive in the order. The latter is characterized by, on the contrary, a relatively slow increase of mean arm ratio and a relatively rapid rise of the ratio of chromosome size and it comprises Metasequoia, Sequoiadendron, Sequoia and Cunninghamia (probably Athrotaxis also), which advance in the order. The inference is supported by the data from morphology, anatomy, embryology and so on.Key words Taxodiaceae; Karyotype; Evolutionary line     

毒药树属的核型及其系统学意义

研究了单型属毒药树属Sladerua的核型,并与被认为有关的狭义山茶科、厚皮香科和猕猴桃科等进行了核型比较。毒药树属的体细胞中期染色体数目为2n=48,核型公式2n=4x=48=4M 36m 8sm,核型为2A型,没有发现随体和次缢痕。体细胞间期核为浓密分散型,前期核为中间型。结果表明,毒药树属与相关类群不但在染色体基数上有差异,而且在染色体大小、核型、间期核、前期核以及随体的有无等方面都不尽相同。研究结果不支持目前分子研究的观点,即把毒药树属放在厚皮香科,且认为它与猕猴桃科和狭义山茶科的亲缘关系也较远。     

Phylogenetic Analysis of the Family Taxodiaceae

In the present paper,both cladistic analysis and phenetic analysis were conducted to evaluate the phylogenetic relationships of the Taxodiaceae based on an extensive literature review and study of herbarium． In the cladistic analysis,the Sciadopityaceae was chosen as outgroup．The polarity of characters was determined mainly according to outgroup comparison,fossil evidence and generally accepted viewpoints of morphological evolution．By the result of compatibility analysis,character 2(leaf type),which possessed a much higher coefficient than others whether or not its polarity was altered,was deleted． Finally,a data matrix consisting of all the extant nine genera and 24 characters was analyzed using Maximal Same Step Method,Synthetic Method,Evolutionary Extremal Aggregation Method and Minimal Parallel Evolutionary Method,and four cladograms were generated,of which only the most parsimonious one (Fig．1)was presented for discussion. The cladogram shows that the Taxodiaceae are assorted along five lines of evolution： 1)Metasequoia;2)Sequoiadendron,Sequoia;3)Cryptomeria;4)Glyptostrobus and Taxodium;5)Cunninghamia,Athrotaxis and Taiwania． Ten genera(including Sciadopitys)and 59 characters were used in the phenetic analysis．The phenogram(Fig．2)indicates that Sciadopitys is a very distinct group with remote affinity to the other genera,and the Taxodiaceae are divided into four groups：1)Sequoia,Sequoiadendron;2)Athrotaxis,Cunninghamia and Taiwania;3)Cryptomeria,Glyptostrobus and Taxodium;4)Metasequoia． Based primarily on the result of cladistics,with reference to that of phenetics,the main conclusions were drawn as follows：(1)Generic relationships：Cryptomeria should be considered the most primitive genus in the extant groups of the Taxodiaceae. Glyptostrobus and Taxodium, close to Cryptomeria, are sister taxa and relatively primitive groups. Sequoiadendron and Sequoia are closely related and intermediate advanced. Metasequoia is a more or less isolated taxon, relatively close to Sequoiadendron and Sequoia. Cunninghamia. Athrotaxis and Taiwania might represent a single lineage and form a very advanced group, of which Taiwania may be the most specialized. (2) Systematic treatments: The authors support the viewpoint that Sciadopitys should be treated as an independent family, and suggest that the Taxodiaeae should be divided into five tribes. Systematic arrangements are as follows: Taxodiaceae Warming Trib. 1. Cryptomerieae Vierhapper Gen. 5. Sequoia Endl. Gen. 1. Cryptomeria D. Don Trib. 4. Metasequoieae Pilger et Melchior Trib. 2. Taxodieae Benth. et Hook. Gen. 6. Metasequoia Miki ex Hu et Cheng Gen. 2. Glyptostrobus Endl. Trib. 5. Cunninghamieae Zucc. Gen. 3. Taxodium Rich. Gen. 7. Cunninghamia R. Br. Trib. 3. Sequoieae Wettstein Gen. 8. Athrotaxis D. Don Gen. 4. Sequoiadendron Buchholz Gen. 9. Taiwania Hayata     

落羽杉属(杉科)叶表皮结构及气孔参数

落羽杉属Taxodium Rich.现生3种植物——落羽杉T. distichum (L.) Rich.、池杉T. ascendens Brongn.和墨西哥落羽杉T. mucronatum Tenore.的条形叶为双面气孔型或单面气孔型。叶片远轴面气孔分布于中脉两侧,每侧各有4-8列气孔。叶片中部气孔数量稳定,顶部和基部气孔数量比中部略少。近轴面气孔在中脉两侧各有1-4行,有时仅少数几个气孔或没有气孔分布。非气孔分布区内,表皮细胞长方形,细胞壁直或稍微呈波状,细胞长轴与叶片长轴一致。气孔分布区内的表皮细胞有时为多边形。气孔器椭圆形,长轴与叶片长轴垂直或成一定的角度。保卫细胞壁加厚明显,极端联合形成极层结构。落羽杉属3种现生植物的气孔密度和气孔指数差异显著,不同采集地的落羽杉气孔密度和气孔指数差异不显著。这3种植物的气孔指数的变异系数均小于气孔密度的变异系数,用气孔指数指示大气CO2浓度比用气孔密度可靠。     

The Karyotype Analysis of Somatic Chromosomes in Amborella trichopoda (Amborellaceae)

Amborella trichopoda Baill. (Amborellaceae), which, based on multiple gene analyses, was recently identified as the first branch in the angiosperm evolution, has somatic chromosomes of 2n=26 (x=13). At metaphase all the chromosomes have centromeres at the median position. Chromosomes of one pair are longer than those of the 12 remaining pairs, and have a secondary or small constriction. Based on karyotype analysis, as well as a survey of chromosome numbers in two other earliest lineages (i.e., Nymphaeaceae and Illiciales), the x=13 of Amborella is likely to be derived from x=14. The hypothesis that x=7 is the original base number in the angiosperms was briefly discussed. Received 30 May 2000/ Accepted in revised form 22 July 2000     

吉祥草的花部器官发生及其系统学意义

利用扫描电镜（SEM）观察了吉祥草（Reineckia carnea）（铃兰科）的花部器官发生发育过程。吉祥草花被片、雄蕊的发生方式是由近轴端向远轴端发生的逆单向型（reversed unidirection）,花发育后期花被片合生形成花被筒,花丝与之贴生。伴随花被片、雄蕊发生,三枚心皮也由近轴向远轴方向相继发生,随后彼此合生发育。花序顶部的花易发生花器官数目变异。结合早期花原基形态以及花器官数目变异情况分析,吉祥草的花被片与雄蕊可能是由共同原基分化而成。从花部器官发生式样和花被筒形成时间两方面比较吉祥草属、白穗花属和铃兰属的特征发现,三属中,铃兰属处于相对进化的位置,而白穗花属比吉祥草属更为原始。     

合欢核型的分析

应用根尖压片法对含羞草科合欢属合欢的染色体数目和核型进行了研究,结果表明:合欢体细胞染色体数目为2n=26,核型为:2n=26=18m 6sm 2st,属于“2B”类型。染色体相对长度组成为2n=26=4L 8M2 12M1 2S。从染色体水平证明合欢在系统演化上属于较进化的种类。     

Ovulate cone,pollination drop,and pollen capture in Sequoiadendron (Taxodiaceae)

In Sequoiadendron ovules are borne inside the ovulate cone, and pollination drops secreted from these ovules collect pollen. We examined: (1) the relation between ovular position and pollen capture; (2) pollen behavior when in contact with a pollination drop; and (3) ultrastructure of ovules during pollination drop secretion. During wet periods a water sheet forms on the surface of the cone due to bract shape and wettability. Pollination drops persist inside the wetted cone, and pollen capture resumes immediately after drying. Pollen landing on a pollination drop is taken inside the drop and carried into the micropyle when the drop contracts. Several notable ultrastructural features appear in the nucellus, integument, chalaza, and bract lamina during pollination-drop secretion. The abaxial surface of the lamina is covered by a membrane that may contribute to the wettable nature of the surface.     

The Karyotype Analysis of Triticum monococcum

The comparisom of karyotypes between 10 different materials of T. monococcum and T. boeoticum was carried out using flame-drying slides prepared by smear method. Cytological observation shows that their karyotypes appear very similar and may belong to the genome A of wheat. They both are found to possess 7 pairs of chromosomes (2n=14), i.e. 5 pairs of metacentric and 2 pairs of submetacentric chromosomes. All the No. 5 chromosomes have a satellite.     

三褶虾脊兰的核型分析

采用压片法研究了三褶虾脊兰[Calanthe triplicata(Willem.)Ames]的染色体数目和核型.结果表明:三褶虾脊兰的染色体数目2n=38,为二倍体,核型公式为2n=2x=38=28m 8sm 2st.主要由中部和近中部着丝点染色体组成.核型分类为2B型,比较对称.     

The Morphology of Fruits and Starches in Bamboos,and Its Relation to Systematic Position

In this article, 30 speceis of bamboos, including 19 genera in 5 tribes, were collected and the morphology of fruits and starches of them was studied. The results are as follows. I. The morphology of fruits is important in studies of systematic position in bamboos. According to the systems of W. Munro and G. Bentham whether the pericarp is adhesive to or free from the seed coat may be taken as a basis of classification. It is also confirmed in this article. It is found in this work that all taxa with a binding pericarp and seed coat are of caryopsis that also has a ventral suture and hilum, while all others with a separated pericarp and seed coat are of bacca or nut, which has no ventral suture and hilum. The former has a hard and thin pericarp and rich endosperm, while the latter has a fleshy and thick pericarp and no endosperm. These characteristics form a basis of classification of major groups. II. In 1907, Brandis found that no any endosperm in matured fruit of Dinochloa, Melocalamus, Melocanna and Ochlandra. It has been proved by Stapf in at least one genus. We found that the baccae of Qiongzhuea, Melocanna, Ferrocalamus and Chimonobambusa Subg. Oerocalama were empty, with no endosperm. This may be a common character of the bacca. We believe, therefore, that the systematic position of Qiongzhuea, Ferrocalamus and Chimonobambusa Subg. Oreocalama is close to Melocanneae. III. Starch grains of bamboo fruits are complex in structure. They are round or ellipsoidal, consisting of 3-22 polyhedral or apple-like small grains. The morphology of starch grains is not so important as fruit in bamboo classification, but some characteristics are of a high value in the identification of genera and species, when they are combined with other features. In Cephalostachyum, the starch grain is very big, with 20-40 μm in diam, and the starch small grain is polyhedral or apple-like with 7.5-22.5 μm in diam, while in Dendrocalamus, the starch grain is small, with 10-28.9 μm in diam. and the starch small grain is only polyhedral, with 3-11.9 μm in diam. The morphology and size of the starch grain and starch small grain are also different in Melocanna and Chimonobambusa Subg. Oreocalama. IV. W. Munro’s system divided Bambuseae into three major groups according to the morphology of flower and fruit. Because the material was not sufficient at that time, the system wrongly put Cephalostachyum, Dendrocalamus into the group Bacciferea. Now it is found that both Cephalostachyum and Dendrocalamus have a nut. Later G. Bentham found this problem and divided the Bambuseae into four subtribes, treating Dendrocalamus as a separate subtribe, Dendrocalamae, and putting the bacca group into another subtribe, Melocannae. It is better, but it also has some shortcomings. Hackel, Gamble, E. G. Camus, A. Camus and Keng Pojie all accepted the view of Bentham, placing Dendrocalamus and Melocanna into different subtribes or tribes.     

长春花核型的研究

对长春花属的长春花(Catharanthus roseus(L.)G.Don)、白长春花(C. roseus(L.)G.Don'Albus')和黄长春花(C.roseus(L.)G.Don'Flavus')的染色体数目和核型进行了研究.结果表明,它们的核型公式均为2n=2x=16=2m 12sm 2T,均属于"3A"核型,染色体数目均为2n=16,但它们的端部和中部着丝点染色体在核型分析中的排列次序不同.     

Reconstruction of the Jurassic conifer Sewardiodendron laxum (Taxodiaceae)

Compressed seed cones and pollen cones of Sewardiodendron laxum are described from the Middle Jurassic of Yima, Henan, central China. They are either organically attached to or associated with leafy shoots. Seed cones are terminally borne. Each cone is ovate to elongated, up to 6.5 cm long and 3.5 cm wide, and consists of a stout axis and numerous helically arranged bract-scale complexes. The bract protrudes beyond and is partially fused with the reduced ovuliferous scale. The ovuliferous scale bears approximately six inverted, small, and flattened seeds. Pollen cones are borne in terminal clusters. Microsporophylls are helically arranged, each bearing three abaxial, basally fused pollen sacs. Pollen is assaccate, rounded, and with an inconspicuous pore. Morphological, structural, and cuticular features of seed cones, pollen cones, and leafy shoots of S. laxum are compared with those of fossil and extant conifers. S. laxum is included in Taxodiaceae and believed to have its closest affinities with a Mesozoic conifer Elatides and a group of Cunninghamia-like conifers. It is reconstructed as a half-evergreen tree that lived in a humid, warm-temperate climate.     

新疆独尾草属植物的核型分析

对新疆独尾草属（Eremurus）植物的核型进行了研究。核型公式如下：阿尔泰独尾草[E.altaicus（Pall.）Stev.]2n=2x=14=4m＋8sm＋2st;异翅独尾草[E.anisopterus（Kar.et Kit）Regel]2n=4x=28=4m＋4sm＋20st;粗柄独尾草[E.inderiensis （M.Bieb）Regel]2n=2x=14=10sm＋4st,首次发现古尔班通古特沙漠南缘所产的异翅独尾草2n=4x=28,与前人报道其为二倍体2n=2x=14的结果不一致。     

绒毛白蜡的核型分析

应用根尖压片法对木樨科白蜡属绒毛白蜡(Fraxinus velutina)的染色体数目和核型进行了研究。结果表明:绒毛白蜡体细胞染色体数目为2n=22,核型公式为:K(2n)=22=20m 2 sm,属于"1A"类型。染色体相对长度组成为2n=22=4L 10M2 8M1。     

The Studies on the Karyotypes and Cytogeography of Taxodium Rich.(Taxodiaceae)

The present paper deals with the karyotypic analysis of Taxodium ascendens Brongn. The somatic chromosomes in root-tip cells of the plant are found to be 2n =22, all with median and submedian constrictions. A character of the karyotype is that the chromosome 10 has a long kinetochore region (Plate 1:1). According to the terminology defined by Levan et al.^[18], the karyotype formula is k(2n)=22=20m+2sm, which is different to Huang et Hsu’s^[8] K(2n)=24=22m+2B(m). The karyotype belongs to “lA” of Stebbins’^[24] karyotypic symmetry and is generally regarded as a relatively primitive one. The species’ chromosome complement is 2n=22=2L+8M₂+12M₁ according to I.R.L.difined by Kuo et al.^[15] based on relative length. The lengths, arm ratios and types of chromosomes of the species are given in Table 1-I. The morphology of the chromosomes and the karyotype, are given in Plate 1:1. In the light of the works of Schlarbaum et al.^[21] and Mehra et al.^[17], K(2n)=22=20m (2SAT)+2sm and 2n=22=2L+6M₂+14M₁ are for T. distichum (L.) Rich. (see Table 1-II), K(2n)=20m+2sm and 2n=22=4L+4M₂+12M₁+2S for T. mucronatum Tenore (see Table 1-III, Plate 1:2), which belong to “lA” and “2A” respectively. The differences between three species in the ratio of the longest to the shortest chromosome, I.R.L. and the proportion of chromosomes with arm ratio >2 show that the karyotype of T. mucronatum is the most advanced and that of T. distichum the most primitive. The present author suggests that the sequence of evolutionary advance be T. distichum, T. ascendens, T. mucronatum. Based on the evidence from the karyotype analyses, ecology and geographical distribution (including fossil), the secondary center of genetic diversity (Fig. 1) and the probable evolu-tionary pattern (Fig. 2) of Taxodium are discussed.     

铁箍散(五味子科)的核型研究

采用常规制片方法首次对铁箍散(Schisandra propinqua（Wall.）Baill.)做了核型分析,结果表明铁箍散体细胞染色体数目为2n=28,核型公式为2n=2x=20m+8sm,染色体相对长度组成2n=28=2L+14M₂+8M₁+4S,染色体长度比为2.14,核型类型为2B型,核型不对称系数0.59,无次缢痕和随体。铁箍散的核型特点表明其在五味子属中处于较进化的地位。     

哈萨克斯坦中部(Kaydagul Formation) 欧洲水松的角质层结构分析

研究了哈萨克斯坦中部上渐新统/下中新统的欧洲水松(Glyptostrobus europaeus (Brongn.) Ung.)的枝叶微形态结构,并利用扫描电子显微镜和光学显微镜与"现存最近亲缘种"--水松(G. pensilis C. Koch)的表皮特征进行了比较.     

Cytological Investigation of Taiwania flousiana Gaussen (Taxodiaceae)

The present paper deals with the cytological investigation of Taiwania flousiana Gaussen. The somatic chromosomes in root-tip cells of the plant are found to be 2n=22 for the first time, all with median and submedian constrictions. According to the terminology defined by Levan et al.^[11], the karyotype formula is K(2n)=16m+6sm, which belongs to “2B” of Stebbins'^[16,17] karyotypic symmetry and is generally regarded as a relatively primitive one. The species' chromosome complement is 2n=22=4L+6M₂+8M₁+4s according to the standard defined by Kuo et al.^[10] based on relative length. The nucleolus number in resting root-tip cells of T. flousiana is found to be 1-5 (Table 3). The percentage of cells with two nucleoli is 77.6%, and those with five nucleoli, the highest number ever found by me, is only 1.6%. A few cells with many micronuclei are found in this species for the first time (Plate 1, 1). Although T. flousiana and T. cryptomerioider have the same “2B” type of karyotypic symmetry, the differences in the arm ratio and the index of the karyotypic asymmetry (Table 2) show that the karyotype of the former is less symmetrical than that of the latter, so the former may be a little more advanced than the latter. The basic karyotype (2B) of Taiwania is more related to that of Cunninghamia (1B)^[3] than to that (1A) of Metasequoia^[5], Glyptostrobus^[4] and Cryptomeria^[3]. Wang et al.^[1], have reached the similar conclusion from the embryological study.