Seed coat morphology and evolution in Celtidaceae and Ulmaceae (Urticales)

The seed coat surface morphology of Celtidaceae and Ulmaceae (Urticales) indicates a significant evolutionary diversity.Celtis, Chaetachme andPteroceltis (Celtidaceae) have a unique sculpturing with many crateriform holes; such holes occasionally sparsely occur in seeds ofAphananthe, Gironniera (Celtidaceae) andPlanera (Ulmaceae), but not in those of the nine remaining genera of the two families. The perforated seed coat further occurs in at least some genera of all other urticalean families. A pattern of its occurrence in families and genera suggest that the perforation represents a common archaic feature of all Urticales, rather than a feature derived many times independently within the order. The seed coat of Celtidaceae and Ulmaceae seems to have lately lost the holes probably by a neotenic evolution: one or more times within Celtidaceae, and one time in an ancestral line leading to all Ulmaceae. The derived reticulate seed coat surface sculpturing, which is shared byGironniera (Celtidaceae) and some Ulmaceae, is probably the result of parallel evolution. On the basis of evidence from seed coat morphology and other sources, close relationships ofLozanella, Parasponia andTrema within Celtidaceae, as well as variously distinct positions ofAmpelocera, Aphananthe andGironniera, are also discussed.     

Gynoecial vascular anatomy and its systematic implications in Celtidaceae and Ulmaceae (Urticales)

Vasculature in the bicarpellate, pseudomonomerous gynoecium with two distinct styles is examined and compared in all of 15 genera of Celtidaceae and Ulmaceae (Urticales). Gynoecial vasculature is diversified in the families but consistet in a genus or a group of genera. Our observations corroborate the earlier suggestion that Ulmaceae (six genera) basically have three-bundled styles, while Celtidaceae (nine genera) always have one-bundled styles. Comparisons with other Urticales and with Eucommiaceae as an outgroup of Urticales indicate that Celtidaceae are more closely related to Moraceae in sharing one-bundled style (a synapomorphy), rather than to Ulmaceae. This supports a separation of Celtidaceae as a distinct family from Ulmaceaesensu lato. Based on the degree of fusion of major vascular bundles running in the gynoecium, we further distinguish three types of gynoecial vasculature in Ulmaceae and, likewise, three types in Celtidaceae, and discuss evolutionary trends of gynoecial vasculature as well as some generic relationships within the families.     

Vernation patterns in Celtidaceae and Ulmaceae (Urticales), and their evolutionary and systematic implications

In two associated families, Celtidaceae and Ulmaceae, vernation pattern (represented by spatial relationships between leaf lamina and stipules, the presence or absence of stipular fusion, lamina orientation, and lamina folding pattern) is consistent within a genus but shows a significant diversity within a family. Six vernation types are distinguishable and tentatively named: 1) Celtis type (Aphananthe, Celtis, Lozanella, Parasponia, Pteroceltis, Trema), 2) Chaetachme type (Chaetachme), 3) Gironniera type (Gironniera), 4) Holoptelea type (Ampelocera, Holoptelea, Phyllostylon), 5) Zelkova type (Hemiptelea, Planera, Zelkova), and 6) Ulmus type (Ulmus). The former three types (found in most of celtidaceous genera) possess free or fused stipules inside of the lamina; in contrast, the latter three types (found in all six ulmaceous genera andAmpelocera) are characterized by having the free stipules outside of the lamina. Within Celtidaceae, Celtis type is probably primitive in having free stipules and an ordinarily oriented lamina; Chaetachme type (with fused, convolute stipules and obliquely oriented laminas) and Gironniera type (with laterally oriented laminas) are the derived. Likewise, within Ulmaceae, both Zelkova and Ulmus types (with laterally oriented laminas) are the derived, while Holoptelea type (with ordinarily oriented laminas) is primitive. Comparisons in vernation pattern suggest the distinctness of Celtidaceae from Ulmaceae and the isolated position ofAmpelocera.     

Karyomorphology of some Moraceae and Cecropiaceae (Urticales)

The karyomorphology of 16 species in 13 genera representing Moraceae and Cecropiaceae was investigated in an effort to contribute to a better understanding of chromosome features and evolution in the families. All genera investigated have similar karyomorphology, but differences are found in (1) chromosome features of Interphase nucleus (simple, simple-complex, or complex chromocenter type), (2) basic chromosome number (x=13 or 14), (3) size variation (mono-or bimodial), and (4) frequencies of chromosomes with median centromeres (m-chromosome) (25–85%) and those with subterminal (or terminal) centromeres (st-chromosome) (14–69%). Comparisons with Ulmaceae as an outgroup of the remainder of Urticales suggest that the simple chromocenter type,x=14 comprising bothm- andst-chromosomes, and the monomodial karyotype are plesiomorphies in Moraceae and Cecropiaceae. Most of Moraceae and Cecropiaceae retain generalized chromosome features of the order, but have involved a few evolutionary changes in karyomorphology. Based on some detailed karyomorphological data, inter- and infrafamilial relationships are also briefly discussed.     

榆科榉属的植物地理学

榉属是东亚—地中海间断分布局,分属于东亚植物区、地中海植物区及伊朗—土兰植物区。根据现存榉属植物的形态演化趋势、细胞学、孢粉学证据及其化石资料和古地质历史事件相结合分析,该属植物是第三纪温带森林的孑遗成分而且第三纪末期的喜马拉雅造山运动及第四纪的冰川作用是样属植物演化的主要动力。在欧洲,由于喜马拉雅造山运动及第四纪冰川作用的较强烈,使分布于此的榉属植物受到严厉的生存竞争,未能适应环境的物种遭受灭绝,少数进行适应性变异的物种在极端环境条件下生存了下来。而东亚地区由于自然环境相对较稳定,便成了榉属植物的避难所,因此也保留了榉属植物种较为古老的种类。     

Phylogenetic Framework for Trema (Celtidaceae)

We used ITS and trnL sequence data, analyzed separately and combined by MP, to explore species relationships and concepts in Trema (Celtidaceae), a pantropical genus of pioneer trees. Whether Trema is monophyletic or includes Parasponia is still unresolved. Three clades within Trema received moderate to high support, one from the New World and two from the Old World, but their relationships were not resolved. In the New World, specimens of T. micrantha formed two groups consistent with endocarp morphology. Group I, with smaller brown endocarps, is a highly supported clade sister to T. lamarckiana. Group II, with larger black endocarps, is poorly resolved with several subclades, including the highly supported T. integerrima clade. Both Old World clades contain Asian and African species, with three or more species in each region. Trema orientalis is not monophyletic: specimens from Africa formed a highly supported clade sister to T. africana, while those from Asia were sister to T. aspera from Australia.     

Silicon-accumulating idioblasts in leaves of Cecropiaceae (Urticales)

A survey of the structure and mineral composition of leaf idioblasts in the Cecropiaceae was conducted. In all six genera of the family, idioblasts usually occur as trichomes or enlarged epidermal cells and nearly always accumulate Si, in marked contrast to the idioblasts of other members of the Urticales, which mostly possess cystoliths containing abundant Ca and Si. The horizontally elongate, mineralized structures ofPoikilospermum, reported formerly as “cystoliths” also contain mainly Si and little Ca. Six genera of Cecropiaceae share a common character in accumulating abundant Si in idioblasts of the leaf epidermis, while lacking cystoliths composed of abundant Ca and Si.     

Karyomorphology and relationships in some genera of Saururaceae and piperaceae

Karyomorphological observations were carried out on three genera belonging to the Saururaceae and four genera of the Piperacea. All of the genera of Saururaceae show the same karyomorphological characteristics from interphase to metaphase in the somatic cell divisions. However there are two types of the karyomorphology in Piperaceae, i) the first type observed inPiper, Pothomorphe andZippelia, and ii) the second type inPeperomia. Each group corresponds to Thorne's two subfamilies (1974, 1976), Piperoideae and Peperomioideae. The basic chromosome numbers of the genera are confirmed or newly proposed as follows:Saururus x=11,Houttuynia x=12,Anemopsis x=22 (Saururaceae),Peperomia x=11,Piper andPothomorphe (=Heckeria) x=13,Zippelia x=19 (Piperaceae). The relationships of these basic chromosome numbers are presumed to be as shown schematically in Fig. 4. The original basic chromosome number of the common ancestral stock of Saururaceae and Piperaceae is presumed to be x=11.     

Karyomorphology of the genusLycopodium sensu stricto and relationships among species

Karyomorphological comparisons were made of six species of JapaneseLycopodium sensu stricto. There were no marked differences at interphase and prophase among the six species.Lycopodium annotinum had 2n=68 and the formula of its metaphase karyotype was 18m(median centromeric chromosomes)+12sm(submedian)+12st(subterminal)+26t(terminal).Lycopodium casuarinoides had 2n=68=16m+10sm+18st+24t,L. clavatum 2n=68=22m+12sm+18st+16t, andL. obscurum 2n=68=10m+22sm+20st+16t. Each of these species, which belong to different sections, displayed several karyomorphological differences. Among themL. casuarinoides differs largely from the others in its mean chromosome length, ratio of the longest chromosome to the shortest, and frequency of m+sm chromosomes. BothLycopodium complanatum andL. nikoense, belonging to sectionComplanata, had a common karyotype 2n=46=10m+12sm+18st+6t. This section displayed a low differentiation in its karyotype. In the wholeLycopodium s.s., the ratios of m+sm in a complement varied from 38 to 50%, being higher among pteridophytes.     

Root-nodule symbiosis between Rhizobium and Parasponia (Ulmaceae)

Summary Evidence of root nodulation and N₂ fixation byParasponia parviflora Miq. found earlier by Akkermanset al. ^{1, 2} was confirmed, although with a lower value for N₂ fixation. In contrast to the above-mentioned investigation, theParasponia trees examined in the present study were growing under natural conditions.The evidence giving by Akkermanset al. ^{1, 2}, that Trinick's Trema is aParasponia species was confirmed by cytological and structural studies of Parasponia root nodules, which resembled closely the Trema root nodules of Trinick¹⁹. Moreover, evidence was obtained thatTrema cannabina Lour. growing in natural habitat on Java and two imported, hitherto unexamined,Trema species (T. micrantha andT. guineensis) bore no root nodules.Isolates fromParasponia parviflora root nodules produced effective root nodules both in sterile Parasponia seedlings and sterileVigna unguiculata (cowpea) andMacroptilium atropurpureum plants confirming their identity as Rhizobium.     

淫羊藿属十二个种的核型

用细胞压片法对12个淫羊藿属(Epimedium)植物的根尖有丝分裂进行了观察,并对其核型进行了比较研究。结果表明:这12种淫羊藿在核型上基本相似,都有1对中间随体染色体,而且都为对称核型。粗毛淫羊藿(E.acuminatum)、印江淫羊藿(E.yinjiangense)、单叶淫羊藿(E.simplicifloum)、巫山淫羊藿(E.wushanense)、光叶淫羊藿(E.myrianthum)、宝兴淫羊藿(E.davidi)、罗甸淫羊藿(E.luodianense)、木鱼坪淫羊藿(E.franchetii)、箭叶淫羊藿(E.sagittatum)、E.pubigerum、高山淫羊藿(E.alpinum)等11个种的核型公式均为2n=2x=6m(2SAT) 6sm,而黔岭淫羊藿(E.leptorrhizum)的核型公式为2n=2x=8m(2SAT) 4sm。结果显示12种淫羊藿的体细胞染色体数目均为2n=12,基数X=6;都属于对称核型、都有1对中间随体;染色体均为m、sm两种类型。     

鸡骨常山属三个种的核形态

研究了鸡骨常山属（Alstonia）3个种的核形态,其中盆架树（A.rostrata）的核型属首次报道,3个种的体细胞染色体数目均为2n=42,且糖胶树（A.scholaris）和鸡骨常山（A.yunnanensis）的染色体数目同前人报道的2n=44不同。盆架树的间期核和有丝分裂前期染色体分别为棒状前染色体型和中间型,核型公式为2n=42=3M＋21m＋18sm,核型不对称性类型为2A型。糖胶树的间期核和有丝分裂前期染色体分别为球状前染色体型和中间型,核型公式为2n=42=14m＋24sm＋4st,核型不对称性类型为3A型。鸡骨常山的间期核和有丝分裂前期染色体分别为复杂染色体中央粒型和中间型,核型公式为2n=42=5m＋37sm,核型不对称性类型为3B型。根据核形态结果,结合形态学特征和已有的细胞学资料,初步讨论了该属几个种的系统位置及演化趋势。     

三种木莲属(木兰科)植物的核型研究

为探讨巴东木莲 (Manglietiapatungensis)的分类学地位 ,对巴东木莲以及它的近缘种红花木莲 (M insignis)和乳源木莲 (M yuyuanensis)进行了核型研究。乳源木莲和巴东木莲的核型公式为 2n =34m (2sat) 4sm ,红花木莲的为 2n =32m 6sm (2sat)。结合前人的研究说明木莲属的核型比较稳定 ,核型不对称性均为较对称的 2B型 ,只是在核型不对称系数、染色体相对长度、最长染色体与最短染色体比值等方面有细微差异。红花木莲和巴东木莲的核型为首次报道。核型分析结果不支持将巴东木莲归并到红花木莲中的分类学处理     

富民枳的核型与分类位置探讨

报道了富民枳(Ponciruspolyandra)的染色体核型。间期核和有丝分裂前期染色体分别为球状前染色体型和中间型;体细胞中期染色体数目为2n=18,核型公式为2n=2x=18=12m 6sm(2SAT);核型不对称性类型为1A。将上述结果与前人报道过的枳和枳橙的核型进行比较。根据富民枳、枳和枳橙之间的核型差异,并结合富民枳形态学、孢粉学、叶片同工酶和分子系统学等方面的研究成果进行综合分析,我们认为富民枳能够以种的地位存在于枳属中,且是较枳更为原始的种类。     

Karyomorphology ofCoriaria (Coriariaceae): Taxonomic implications

Karyomorphology ofCoriaria, the only genus of the family which is controversial with respect to its affinities and the number of constituting species, is investigated on the basis of ten species (including eight narrowly defined species) representing nearly all the variation of the genus. Features common to all the species investigated are: (1) interphase nucleus has a few small or large, condensed heterochromatic blocks; (2) chromosomes at metaphase are mostly small (0.4–0.7 μm long by our methods); (3)x=20. Resemblances in chromosome morphology suggest that Coriariaceae may have affinities with Rutales/Sapindales. Differences among species are found in (1) whether somatic chromosomes are diploid (2n=40) or tetraploid (2n=80); (2) the presence or absence of a few chromosomes with thick heterochromatic segments at metaphase; when such chromosomes are present, (3) their number and (4) morphology. Karyomorphology defines wellCoriaria myrtifolia, C. napalensis andC. japonica, and further provides evidence for distinguishing at least four species withinC. ruscifolia sensu Skog.     

Karyomorphology of six taxa in Chrysanthemum sensu lato (Anthemideae) in Egypt and their genetic relationships by Giemsa C-banding

Giemsa C-banding was applied to the chromosome complements of six diploid species belonging to six genera in Chrysanthemum sensu lato (Anthemideae) distributed in Egypt.Four types of C-banding distribu...     

Karyomorphology of Taiwanese Begonia (Begoniaceae): taxonomic implications

 The karyomorphology of all 14 species of Taiwanese Begonia was investigated to elucidate their chromosome features and chromosomal evolution. Among all species investigated, differences in chromosome features are found in: (1) chromosome number 2n = 22, 26, 36, 38, 52, 60, 64, 82, and (2) frequencies of chromosomes with secondary, tertiary, and/or small constrictions of polyploids, ranging from 23% to 63%, which is higher than the expected value of about 9%. It is suggested that after polyploidization from the diploid species (i.e., 2n = 22 and frequencies of chromosomes with secondary, tertiary, and/or small constrictions of polyploids of about 9%), chromosome translocations occurred, followed by a decrease in chromosome number, and subsequently stabilized genomes were formed in various species in Taiwan. The karyomorphological evidence also suggested that the chromosome morphology has evolved in parallel in the begonias belonging to different sections in Taiwan. The variation in chromosomal features is more complex than the variation in floral and fruit morphologies. Karyomorphological data also supports the recognition of five new species in Taiwan: Begonia bouffordii, B. chuyunshanensis, B. pinglinensis, B. tengchiana, and B. wutaiana. Based on detailed karyomorphological analyses, the taxonomic implications, speciation, and chromosomal evolution in Taiwanese Begonia are discussed. Received: January 22, 2002 / Accepted: March 4, 2002     

Karyomorphology of Taiwanese Begonia (Begoniaceae): taxonomic implications

The karyomorphology of all 14 species of Taiwanese Begonia was investigated to elucidate their chromosome features and chromosomal evolution. Among all species investigated, differences in chromosome features are found in: (1) chromosome number 2 n = 22, 26, 36, 38, 52, 60, 64, 82, and (2) frequencies of chromosomes with secondary, tertiary, and/or small constrictions of polyploids, ranging from 23% to 63%, which is higher than the expected value of about 9%. It is suggested that after polyploidization from the diploid species (i.e., 2 n = 22 and frequencies of chromosomes with secondary, tertiary, and/or small constrictions of polyploids of about 9%), chromosome translocations occurred, followed by a decrease in chromosome number, and subsequently stabilized genomes were formed in various species in Taiwan. The karyomorphological evidence also suggested that the chromosome morphology has evolved in parallel in the begonias belonging to different sections in Taiwan. The variation in chromosomal features is more complex than the variation in floral and fruit morphologies. Karyomorphological data also supports the recognition of five new species in Taiwan: Begonia bouffordii, B. chuyunshanensis, B. pinglinensis, B. tengchiana, and B. wutaiana. Based on detailed karyomorphological analyses, the taxonomic implications, speciation, and chromosomal evolution in Taiwanese Begoniaare discussed.