FLOWERING BEHAVIOR OF THE NEOTROPICAL GENUS ANTHURIUM (ARACEAE)

The genus Anthurium (Araceae) is one of the most taxonomically complex genera in the neotropics. Studies of living material have shown modes of behavior which probably have a direct influence on pollination biology and evolution. Separation of the sexes is generally accomplished by marked protogyny. Considerable differences also exist in the rate of development of flowers, the presence, source and amount of stigmatic nectar, as well as the method of pollen presentation. The genus exhibits an unusual pattern of staminal emergence. In all species studied, the lateral pair of stamens are first to emerge, usually one at a time, followed by the anterior, then the posterior stamens of the alternate pair. There are also differences in the degree of exsertion, the disposition with respect to the stigma, degree of retraction and changes in pollen color. Some species have stamens which are retracted completely after opening: others have stamens which scarcely emerge but instead force the pollen out in long ribbons. Important differences also exist in flower aromas with both fly and bee pollination syndromes exhibited. All of these aspects of flowering behavior are natural phenomena believed to be important in pollination biology.     

HYBRIDS AND PHYLOGENETIC SYSTEMATICS I. PATTERNS OF CHARACTER EXPRESSION IN HYBRIDS AND THEIR IMPLICATIONS FOR CLADISTIC ANALYSIS

Interspecific hybridization is considered common among plants, but the methods of cladistic systematics produce only divergently branching phylogenetic hypotheses and thus cannot give the correct phylogeny if an analysis includes hybrids. Empirical studies of the impact of known hybrids on phylogenetic analysis are lacking, and are necessary to begin to understand the problems that we face if hybrids are often included in cladistic analysis. Examination of the implications of hybrids for cladistics must begin with patterns of character expression in hybrids. This study includes 17 hybrids and their nine parental taxa that are Central American species of Aphelandra (Acanthaceae), analyzed using a set of 50 morphological characters. The hybrids are overwhelmingly intermediate as quantitatively scored for phylogenetic analysis. They express maternal and paternal, and primitive and derived characters in equal frequencies, showing no evidence of predominant inheritance of derived character states as has been assumed by most cladists who have considered hybrids theoretically. Because of their known genetic constitution, hybrids were useful in homology assessment and ordering character states. The parental character set was generally robust, but some changes were made to reflect the special evidence offered by the hybrids. These hybrids suggest that the inclusion of hybrids in phylogenetic analysis will not lead to unresolved cladograms with rampant homoplasy, as has been predicted by other authors. Instead, the patterns of character inheritance in these hybrids lead to the prediction that a hybrid will be placed by phylogenetic analysis as a basal lineage to the clade that includes its most derived parent, with relatively little effect on homoplasy. These predictions will be evaluated by incorporation of the hybrids in phylogenetic analyses, to be reported in a subsequent paper.     

半夏属若干变异式样及其演化

通过数量统计和栽培观察,发现半夏属具有子块茎Ｔｎ＾ｍ,子块茎根状茎Ｔｎ＾ｍＲｂ＾ｎ,子块茎根状茎珠芽Ｔａ＾ｍＴｎｚ＾ｎＢｃ＾ｒ和子块茎株芽Ｔａ＾ｍＢｃ＾ｒ４种组合形式的无性繁殖式样。属内经历了从根状茎（Ｒ）揶块茎（Ｔ）到珠芽（Ｂ）和盾形叶到其它叶形的经及其它变化。还讨论了该属的种间进化。     

分布于日本和中国的鹅观草及其杂种的形态学和细胞学研究

本文对分布于日本的Agropyron tsukushiense (Honda) Ohwi var. transiense (Hack.) Ohwi (2n=6x=42)和分布于中国的Roegneria kamoji Ohwi (2n=6x=42)及其杂种F_1(2n=6x=42)进行了形态学及细胞学的研究,并同时探讨了亲本种的亲缘关系。总体来看,亲本材料之间在形态上虽有差异但并不十分显著。杂种F_1的形态特征介于其父、母本之间。在减数分裂过程中,亲本种和杂种F_1的染色体配对行为均十分正常。但在检查了大量的成熟花粉和穗状花序之后,发现杂种F_1有部份不育现象。上述研究结果表明A. tsukushiense var. transiens的三个染色体组与R. kamoji的三个染色体组同源。结合形态学和育性等方面的研究资料,作者认为上述两个材料仍应属于同一分类等级。但必须指出,由于长期的地理隔离,他们之间产生了一定的形态变异和生殖障碍。按照国际植物命名法规(ICBN)上述两个材料应组合为:Roegneria tsukushiensis (Honda) B. R. Lu, Yen et J. L. Yang及其变种var. transiens (Hack.) B. R. Lu, Yen et J. L. Yang comb. nov.     

SHADE TOLERANCE AND ITS EFFECT ON THE SEGREGATION OF TWO SPECIES OF LOUISIANA IRIS AND THEIR HYBRIDS

Iris fulva Ker. Gawler and Iris hexagona Walter have overlapping geographic ranges in Louisiana. In areas of overlap hybrids are fairly common. Iris hexagona occupies the borders of freshwater marshes of southern Louisiana while I. fulva can be found farther north along edges of natural levees, canals and swamps. Where the natural levee penetrates the marsh, natural hybridization can occur between I. hexagona and I. fulva. It has been suggested that one principal explanation for the segregation of the two species is that I. fulva grows best in semishade and I. hexagona grows best in full sun. A greenhouse study was conducted using rhizomes collected from the field to test this hypothesis and determine the relative shade tolerance of two natural hybrid types. Iris fulva, I. hexagona, and the two hybrid taxa were grown under 0% (control), 50% (medium shade), and 80% (high shade) reduction of sunlight for 6 months and then harvested. Iris fulva was found to be more tolerant of shading than I. hexagona and the two hybrids. Further, I. fulva was found to grow as well in control as in medium shade. Both hybrid taxa were more shade tolerant than I. hexagona. Iris hexagona was greatly affected by all levels of shade. In general, the results suggest that these hybrids are intermediate to the parental taxa in terms of shade tolerance.     

山白树属及其近缘属聚类分析

运用系统聚类分析法,对山白树属及其近缘属进行定量分析,结果表明山白树属与牛鼻栓属亲缘关系密切,可组成一族,该族与蚊母树族有着较近的亲缘。     

PHYLOGENY OF THE GENUS COLEOCHAETE (COLEOCHAETALES,CHAROPHYTA) AND RELATED TAXA INFERRED BY ANALYSIS OF THE CHLOROPLAST GENE rbcL1

The genus Coleochaete Bréb. is considered to be a key taxon in the evolution of green algae and embryophytes (land plants), but only a few of the approximately 15 species have been studied with molecular phylogenetic methods. We report here the sequences of the gene rbcL from six new cultures of Coleochaete and two of Chaetosphaeridium Klebahn. These sequences were combined with 32 additional sequences, and phylogenetic analyses were performed with maximum likelihood, distance optimality, and parsimony methods. Important subgroups within Coleochaete include two primary lineages, one marked by fully corticated zygotes and the other by naked or weakly corticated zygotes. In the first lineage there is a subclade with tightly joined filaments and distinctive (“T‐shaped”) cell division, an assemblage of strains that resembles the endophytic species Coleochaete nitellarum Jost, and a clade with loosely joined filaments and “Y‐shaped” cell divisions. Consistent with recent multigene phylogenies, these analyses support the monophyly of the Coleochaetales, place the Charales as the sister taxon to land plants, and indicate that Chaetosphaeridium is far more closely related to Coleochaete than to Mesostigma Lauterborn.     

THE NUCLEAR CYTOLOGY OF BIVALENT AND RING-FORMING RHOEOS AND THEIR HYBRIDS

The structural hybridity of the chromosomes of Rhoeo spathacea (R. discolor) that produces a ring of 12 chromosomes at meiosis is probably maintained by a balanced lethal system active in the zygotic or embryonic stage. Bivalent-forming plants have been identified that belong to the taxon R. spathacea var. concolor. In the clone studied the arm arrangement in R. s. var. concolor is very nearly the same as the arm arrangement in one of the balanced translocation complexes of R. spathacea.     

栉孔扇贝×虾夷扇贝杂交子一代与双亲染色体核型的分析

连续几年栉孔扇贝大面积死亡现象严重制约了北方贝类养殖业的发展 ,造成了巨大的经济损失。栉孔扇贝和虾夷扇贝生物学性状差异较大 ,可望通过杂交途径培育出抗逆性强、生长快的扇贝养殖新品种。杨爱国等[1] 和周丽青等[2 ] 的研究结果表明 ,栉孔扇贝与虾夷扇贝正反交杂交子一代     

异育银鲫及其人工杂合种外源遗传物质的检测分析

采用 DNA 杂交的方法,对异育银鲫及其人工杂合种进行了外源 DNA 的检测分析,发现两个雌核发育系的异育银鲫及其人工杂合种的 DNA 与红鲤 DNA 片段间的分子杂交均有阳性斑点出现,这表明,在异育银鲫及其人工杂合种产生过程中,父本(红鲤)的 DNA 片段的确可以随机地掺入到母本细胞的 DNA 中,从而产生了异精效应,使其子代生长加快,并出现父本性状。     

COMPARATIVE ELECTROPHORETIC STUDIES OF CARDUUS PYCNOCEPHALUS L., C. TENUIFLORUS CURT. (ASTERACEAE), AND THEIR HYBRIDS

Electrophoretic studies on Carduus pycnocephalus L., C. tenuiflorus Curt., and their hybrids, showed that, although hybridization is common, the two parental species are quite well separated by their enzymatic patterns. This was confirmed by data on fertilization and achene abortion rates of the intermediate forms between the two species. The seed set of hybrids was the lowest in California, where the two species have been introduced.     

锡林河流域植物化学成分与植物类群及其生境关系的定量分析

植物化学成分与植物类群和所处生境关系密切。应用系统聚类分析、因子分析（采用主因子法和因子斜交旋转）等多元统计方法对锡林河流域１２２种植物的化学成分与植物类群和所处生境的关系进行了定量分析。分析结果说明上述方法可以较为准确地揭示数据中的如下规律：锡林河流域草原植物化学成分一方面与植物类群有关,受自身历史演化的决定,另一方面更受到所处生境条件的极大影响和制约。其中,禾本科、豆科植物分别具有其明显的化学成分特征;撂荒地群落与自然群落中植物、沙质与非沙质生境中植物化学成分差异较显著。因子分析中认为存在大量元素与微量元素两个公共因子,分别代表着植物中大量元素与微量元素的含量状况。豆科与禾本科相比,豆科植物因其具固氮能力,所含大量元素水平较高,而禾本科植物因细胞壁硅质化,含微量元素稍高;沙质生境因其养分贫瘠,植物的大量与微量元素均较非沙质生境中的低;特别是本区地带性土壤－栗钙土与特异性生境沙带中的疏林沙土相比,疏林沙土上植物大量与微量元素含量较栗钙土区植物明显偏低。     

中国毛茛属新分类群及其核型

新种R．shuichengensis L,Liao有两种核型类型,即基本型2n=2x=16=4m+2sm+10st(2SAT);杂合型2n=2x=16=4m+2sm+9st(1SAT)+1t(1SAT),其核型和近缘种R．trigonus Hand．- Mazz.核型相似,但其随体染色体短臂比后者更小而不同。新变种R．silerifolius var．dolicanthus L. Liao核型(2n=2x=16=4m+2sm+10st(2SAT)与原变种Var．silerifolius不同。根据形态和染色体的特征,我们认为本文中两个新分类群和R．Trigonus是国产毛茛组中x=8至x=7的过渡类群。     

普通烟草和黄花烟草及体细胞杂种过氧化物酶同工酶等电聚焦电泳

日本学者长尾照义(1978)用原生质体融合获得普通烟草与黄花烟草的体细胞杂种植株。1980年陈家玉等在国内首先获得普通烟草(Copus Yeusuku No.4)和黄花烟草(Yellow Flower)的体细胞杂种植株。之后,中国农科院烟草所(1981)也得到相同的结果。陈家玉等(1983)对上述杂种进行了形态学、细胞学和同工酶的分析并取得一定的结果。Dlineee等(1975)分析比较了用等电聚焦技术分离的过氧     

HYBRIDS AND PHYLOGENETIC SYSTEMATICS II. THE IMPACT OF HYBRIDS ON CLADISTIC ANALYSIS

I examined three aspects of the cladistic treatment of a set of 17 F₁ hybrids of known parental origin: (1) impact of hybrids on consistency index (CI) and number of most parsimonious trees (Trees), (2) placement of hybrids in cladograms, and (3) impact of hybrids on hypotheses of relationship among species. The hybrids were added singly and in randomly selected sets of two to five to a data set composed of Central American species of Aphelandra (including the parents of all hybrids). Compared to analyses with the same number of OTUs all of which were species, the analyses with hybrids yielded results with significantly higher CI. There was no difference in Trees between analyses with hybrids versus species. There was thus no evidence that hybrids would appear to be more problematic for cladistic methods than species. Accordingly, hybrids will not be readily identifiable as taxa that cause marked change in these indices. About % of the hybrids were placed as the cladistically basal members of the lineage that included the most apomorphic parent. Relatively apomorphic hybrids were placed proximate to the most derived parent (ca. 13% of hybrids). Other placements occurred more rarely. The most frequent placements of hybrids thus did not distinguish them from normal intermediate or apomorphic taxa. When analyses with hybrids yielded multiple most parsimonious trees, these were no more different from each other than were the equally parsimonious trees that resulted from analyses with species. Most analyses with one or two hybrids resulted in minor or no change in topology. When hybrids caused topological change, they frequently caused rearrangements of weakly supported portions of the cladogram that did not include their parents. When they disrupted the cladistic placement of their parents, they often caused their parents to change positions, with at least one topology bringing the parental lineages into closer proximity with the hybrid placed between them. Hybrids between parents from the two main lineages of the group caused total cladistic restructuring. In fact, the degree of relationship between a hybrid's parents (measured by both cladistic and patristic distance) was strongly correlated with CI (negatively) and with the degree of disturbance to cladistic relationships (positively). Thus, hybrids between distantly related parents resulted in cladograms with low CI and major topological changes. This study suggests that hybrids are unlikely to cause breakdown of cladistic structure unless they are between distantly related parents. However, these results also indicate that cladistics may not be specially useful in distinguishing hybrids from normal taxa. The applicability of these results to other kinds of hybrids is examined and the likely cladistic treatment of hybrids using other sources of data is discussed.     

西伯利亚嵩草及其相关类群的植物分类学及植物地理学研究

研究了产于西伯利亚的西伯利亚嵩草Kobresia sibirica (Turcz.ex Ledeb.) Boeck.,产于北美的K.hyperborea Porsild和K.macrocarpa Clokey。三者之间无显著差异,并且它们的雌花都具有由一至三枚小鳞片组成的花被。因此,它们为同种植物, K.hyperborea包括其变种var.alaskana Duman和var.lepagei Duman及K.macrocarpa被降为西伯利亚嵩草的异名。西伯利亚嵩草分布于亚洲和北美洲的北极和亚北极地区,可能起源于亚洲,由东西伯利亚通过白令海峡散布到北美。     

梅花(Prunus mume Sieb et Zucc)远缘杂种及其亲本的差热分析与冻害关系的研究

用差热分析(Differential thermal analysis: DTA)研究了山桃(Prunus davidiana)、杏(P. armeniaca)、青岛“粉红梅”(P.mume cv.'Fenhong Mei,)、“小绿萼”(P.mume cv.'Small Green Calyx')及其种问杂种“小绿萼”梅×山桃、青岛“粉红梅”×杏和杏×青岛“粉红梅”的低温放热(Low temperature exotherm)与冻害关系,以及皮部和木质部的冰冻类型(Freezing pattern)。在差热分析中,观察到亲本和杂种的木质部都有二次放热现象。低温放热后,引起木质部和髓射线薄壁细胞死亡,原生质膜透性急剧增加。在杂种与亲本之间,存在着明显的差异。分离的皮部却只出现一次高温放热(High temperature exotherm)。高温放热是与冻害无关的。文末讨论了梅花及其杂种在北京越冬的主要障碍及有关栽培措施。