首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
The 26 generic and 63 infrageneric names which have been applied to the approximately 47 species belonging to the Vulpia–Desmazeria group of annual Poaceae: Poeae are listed, together with their bibliographic, nomenclatural and typological details. A synopsis of the classification of this group adopted by the author, involving twelve genera and five extra sections, follows, and includes a new combination at the sectional level: Vulpia sect. Apalochloa (Dumort.) Stace. Although not closely related to this group of grasses, the genus Sclerochloa is included as it has been very widely confused taxonomically, nomenclaturally and typographically with Scleropoa.  相似文献   

2.
A study of a number of reproductive traits in two sympatric species of Pedicularis in northern Swedish Lapland, the subarctic-alpine P lapponica and the artic P hursuta , revealed that the life-history strategies of the two species differ profoundly High fruit set and low seed abortion rate, as m P hursuta , is common in arctic plants in late-thawing habitats and represents a case of extreme adversity selection rather than an indication of a ruderal life-history strategy Pedicularis lapponica , on the other hand, is a typical K-strategist (or stress-tolerator) requiring a longer period of growth for optimal reproduction Occuring at both low and high altitudes in the area, P lapponica tends to increase in self-compatibility with altitude, which is interpreted as an adaptation to lower pollinator visitation frequency in arctic environments The variation in length of the protruding part of the style in P lapponica is shown to be correlated with exposure to light Predispersal seed predation is severe m P lapponica at low altitudes, where the capsules are attacked by fly and moth larvae At high altitudes, a minor proportion of the capsules of P lapponica experience predation and only from flies, while P hursuta is completely unpredated  相似文献   

3.
Baolia Kung et G. L. Chu was established on the basis of B. bracteata Kung et G. L. Chu described in 1978 from Diebu County on the border between Gansu and Sichuan provinces. It is placed in the tribe Chenopodieae in 《Flora Reipulicae Popularis Sincae》, but considering its flowers with a bract and 2 bracteoles it is betwter transferred to the tribe Polvcenmeae. So far the tribe Polycnemeae contains 4 genera in total, i.e. Nitrophila S. Wats. with 4 species, distributed in Southwestern US, Mexico and Argentina, Hemichroa R. Br. with 3 species all in Australia, Polycnemum Dumort. with 4 species in Europe, Mediterranean, Middle Asia to Siberia, Baolia Kung et G. L. Chu with 1 species, occurring in central China with a very limited area.  相似文献   

4.
Self-pollination of Asarum caulescens Maxim. (Aristolochiaceae) in Japan   总被引:1,自引:1,他引:0  
Abstract Observations in two populations of Asarum caulescens belonging to sect. Asarum indicate that inbreeding predominates becuase (1) no effective pollinator was observed, (2) bagged flowers set fruits with well-swollen seeds, and (3) the behaviour of filaments, changing from recurved to straight posture, results in direct deposition of pollen grains on the stigmas. This result agrees with reports on three other species of sect. Asarum in Europe and North America. We suggest that species of sect. Asarum diverged from an autogamous ancestor.  相似文献   

5.
对毛茛科Ranunculaceae铁线莲属Clematis的菝葜叶铁线莲组sect. Naraveliopsis进行了全面修订, 确定此组共含21种1亚种和1变种; 写出此组的分类学简史和地理分布, 并讨论了此组在铁线莲属中的系统位置; 将此组划分为3亚组, 写出分亚组、分种检索表, 以及各种植物的形态描述、地理分布、生长环境等, 并附有多数种的墨线图。根据对此组植物形态特征的分析, 观察到以下重要演化趋势: (1)叶从单叶演变到二回羽状复叶或二回三出复叶; (2)花从两性到单性, 从无退化雄蕊到有退化雄蕊; (3)雄蕊从无毛到有毛; (4)药隔突起从短(0.5-0.7 mm)到长(8.5-10 mm)。根据上述演化趋势,花两性、雄蕊被毛、退化雄蕊存在的荔波铁线莲亚组subsect. Liboenses(1种,特产贵州荔波)和花由两性变为单性的亚组subsect. Macgregorianae(2种,特产菲律宾)被认为是菝葜叶铁线莲组的进化群。在原始的菝葜叶铁线莲亚组subsect. Smilacifoliae(花两性,雄蕊无毛; 18种,广布亚洲热带地区)中,具单叶,花无退化雄蕊,药隔突起较短的菝葜叶铁线莲C. smilacifolia和滇南铁线莲C. fulvicoma被认为是较原始的种,而具三出复叶和退化雄蕊的C. vietnamensis和丝铁线莲C. loureiriana,以及具羽状复叶和长药隔突起(长达10 mm)的C. papillosa等3种则被认为是此亚组的进化种。自中南半岛北部山地向西经云贵高原南部至喜马拉雅东部山区集中分布有菝葜叶铁线莲组的13种植物,这一山区地带被认为是此组的分布中心。在此山区地带中,菝葜叶铁线莲的分布区和滇南铁线莲的分布区重叠部分的山区可能是此组的起源中心。  相似文献   

6.
The delimitation of Solanum sect. Chamaesarachidium, as well as its relationship with sect. Episarcophyllum and certain species of sect. Solanum, is presented. Three species are included in Solanum sect. Chamaesarachidium (S.annuum, S.chamaesarachidium, and S.gilioides), which are described in detail and illustrated. The following combination of characters defines Solanum sect. Chamaesarachidium: the small annual habit, the pinnatifid to pinnatisect leaf blade, the inflorescence opposite or subopposite to the leaves, the number of flowers per inflorescence (3–14), the campanulate corolla, the very small anther size (1.1–2.7 mm long), the accrescent fruiting calyx with a well-marked venation, the absence of sclerosomes in the pericarp, the tuberculate seed coat, and the Andean habitat.  相似文献   

7.
Abstract.  1. The Salicaceae have been suggested as ancestral host plants of Chrysomela species (Coleoptera: Chrysomelidae). In Chrysomela lapponica , some populations are specialised on salicaceous plants, but others have switched to birch. This study aimed to elucidate the significance of natural enemies as possible selective forces for the host plant shift of C. lapponica from willow to birch.
2. Two C. lapponica populations were studied, one specialised on willow Salix borealis in Finland, and another one specialised on birch Betula pubescens in the Czech Republic. Abundances of predators and parasitoids on birches and willows were recorded at both population sites. Furthermore, field and laboratory experiments were conducted.
3. Field data do not support the hypothesis that generalist predators affected the host shift from willow to birch in C. lapponica.
4. Parasitism of C. lapponica (pre)pupae by a specialised phorid fly was significantly stronger in specimens living on willow than in birch-living ones.
5. The predatory syrphid Parasyrphus nigritarsis specialised on Chrysomelinae was only detected on willows. The syrphid preferred to orient towards substrates treated with defensive larval secretion or faeces of the willow-specialised C. lapponica specimens compared with the birch-specialised ones.
6. The data suggest that specialised parasitoids and predators might have been driving forces for C. lapponica to leave willows and to pioneer birches as sites with a lowered risk of predation and parasitism. This hypothesis is discussed with respect to results of earlier studies on the impact of bottom-up effects by the plant.  相似文献   

8.
通过检查藏南翠雀花Delphinium nortonii 的主模式标本,发现《中国植物志》、《西藏植物志》和《Flora of China》中对该种的鉴定和描述有误。该种的花的退化雄蕊黑褐色,属于翠雀亚属的密花翠雀花组subgen. Delphinastrum sect. Elatopsis, 而上述几种植物志中长1以来将其置于退化雄蕊为蓝色或蓝紫色的翠雀组sect. Delphinastrum中。这几种植物志中记载的D. nortonii 实际上代表一个新种,即李恒翠雀花D. lihengianum。  相似文献   

9.
Cousinia brevicaulis is described and illustrated as a new species from eastern Iran. This species belongs to the C. sect. Lasiandra Bunge as defined by hairy anther tube, yellow, pale yellow or rarely milky flowers, monocarpic growth form and corymbose branching of stem. It is easily distinguished from other species of the section by its very short‐stemmed habit. The new species is distributed in the same region as other species of C. sect. Lasiandra.  相似文献   

10.
中国重庆毛茛科银莲花属一新种——涪陵银莲花   总被引:1,自引:0,他引:1  
描述了中国重庆市涪陵区的毛莨科Ranunculaceae银莲花属Anemone一新种——涪陵银莲花A.fulingensisW.T.Wang&Z.Y.Liu,并绘出墨线图。根据此新种的总苞苞片无柄,花具4-5枚萼片,花丝丝形,花粉具散沟等特征,可以确定此种应是属于银莲花属鹅掌草组Anemone sect.Stolonifera的一个成员;在该组中,此种以其独特的由2-10个块茎组成的念珠状根状茎而与该组的其他种相区别。鉴于在银莲花属中块茎出现于不同的演化路线中,以及这些块茎的出现系次生现象,可见此新种应是鹅掌草组的进化种。  相似文献   

11.
Clematis sect. Tubulosae is revised in this paper. Nine species, two varieties, and three forms are recognized and classified into two subsections. An identification key is provided, and each species is described and illustrated. Brief taxonomic history is given, along with a summary of pollen morphology and geographical distribution. The relationships among the infrasectional groups are also discussed: Subsect. Pinnatae, characterized by its scandent habit, bisexual flowers, white or pinkish, at length spreading, obovate-oblong sepals, and tricolpate pollen, is regarded as the more primitive group, whereas subsect. Tubulosae, characterized by its erect habit, usually polygamous flowers, blue or purple, erect, usually narrowly oblong sepals, and usually pantoporate pollen, is regarded as the more advanced group of the section. Subsect. Pinnatae is believed to have originated from sect. Clematis in Central or East China, and subsect. Tubulosae might be derived from subsect. Pinnatae.  相似文献   

12.
Phylogenetic relationships among species of Aeonium were studied using morphological characters and chloroplast DNA RFLPs. Cladistic analysis of weighted morphological data indicates that the small, herbaceous and least woody species are basal in the genus. Chloroplast DNA data gave similar results, supporting the separation of the herbaceous or small, woody species from the large, hapaxanth rosettes, rosette trees, and branched subshrubs with yellow, white or red flowers as well as the only (herbaceous) species with axillary inflorescences. The relationships among the species descending from a polytomy that comprises all species of the genus as well as a polytomy which comprises 18 of the 26 species studied, are only very incompletely resolved, except for two monophyletic clades that contain the branched subshrubs with yellow flowers ( A . sect. Aeonium ) and the branched subshrubs and rosette trees with white or red flowers ( A . sect. Leuconium ), respectively. Cladistic analysis of the combined morphological and chloroplast DNA data improved resolution considerably. Four monophyletic clades are distinguished, each of which, except for three species, comprises only one of the five main growth-form types. Although Aeonium is generally regarded as an outstanding example of adaptive radiation, this mode of speciation seems to have been of minor significance in the evolution of the genus, because each growth-form apparently evolved only once. Instead, island speciation in the absence of major ecological shifts, is probably more important in the evolution of the genus.  相似文献   

13.
Zvereva EL  Rank NE 《Oecologia》2003,135(2):258-267
Larvae of the leaf beetle Chrysomela lapponica obtain salicyl glucosides (SGs) from the host plant to produce a defensive secretion with salicylaldehyde. In northern Russia, larvae and pupae experience high parasitism by the phorid fly Megaselia opacicornis and tachinid fly Cleonice nitidiuscula. We compared the suitability of the SG-rich Salix borealis and SG-poor S. caprea and S. phylicifolia to Ch. lapponica and tested whether enemy pressure on Ch. lapponica varies among host species that differ in SG content. In the laboratory, survival of Ch. lapponica larvae was higher on S. borealis than on S. caprea and S. phylicifolia, while adult body mass was higher on S. borealis and S. caprea than on S. phylicifolia. In the field, parasitism by both M. opacicornis and Cl. nitidiuscula was greater on beetles from S. borealis than from the SG-poor S. caprea or S. phylicifolia. In a laboratory choice test, the pupal parasitoid M. opacicornis laid similar numbers of eggs on beetles reared on SG-rich and SG-poor willows, suggesting that the host plant-derived defence is not effective against this parasitoid. In a field enemy-exclusion experiment, beetle survival was greatly enhanced by the exclusion of enemies, but survival rates did not differ between S. borealis and S. caprea, although larvae developed faster on S. borealis. On the other hand, parasitism and predation were observed more often on S. borealis than on S. caprea. Thus, beetle larvae perform better but also suffer higher predation and parasitism on S. borealis than on SG-poor willows. Ch. lapponica does not appear to obtain enemy-free space by feeding on SG-rich willow species.  相似文献   

14.
Two new species of Miconia from Bolivia are described: Miconia galeiformis and Miconia neei. Both species occur in Andean montane forests. Miconia galeiformis (sect. Chaenopleura) is distinctive within Miconia due to the presence of setose stems, petioles and abaxial leaf surface, and a large, globose stigma. Miconia neei bears unisexual flowers, and can be distinguished from similar species of Miconia sect. Cremanium in Bolivia based on the furfuraceous stems and young nodes, in addition to serrulate leaf margins. The documentation of dioecy in Miconia neei and the occasional occurrence of unisexual flowers in Miconia galeiformis adds to our burgeoning understanding of complex breeding systems within Miconia.  相似文献   

15.
报道了在云南西南部发现的凤仙花属一新种——滇红凤仙花(Impatiens quintadecimacopii G.W.Hu&Q.F.Wang)和一新记录种——伸展凤仙花(I.porrecta Wall.ex Hook.f.&Thomson)。这两个种在形态上很相似,但在花色、侧萼片形状、旗瓣形状和蒴果颜色上明显有别。根据形态特征,这两个种应属于凤仙花亚属(I. subg.Impatiens)单花组(I. sect.Uniflora)。结合核糖体DNA内转录间隔区序列(ITS)与叶绿体atpB-rbcL间隔区序列开展系统发育分析,结果进一步确认了这两个种关系紧密,以及它们在单花组内的系统位置。  相似文献   

16.
在野外和标本研究的基础上, 描述了中国兰科石豆兰属的一新种,怒江石豆兰, 并提供彩色图片和线条图。 怒江石豆兰与大苞石豆兰很近,但这两个种在花的颜色、侧萼片合生程度、花瓣形状等性状上区别明显。  相似文献   

17.
Primula zhui a new species of Primula endemic to the Yunnan Province, China, is described and illustrated. It is morphologically similar to P. intanoensis from Thailand, and P. calyptrata from southeast Yunnan, affiliated to Primula sect. Carolinella (Hemsl.) Pax. However, it is easily distinguished from the Thailand species by its longer corolla tube and distylous flowers, and it differs from the Chinese species by its leaf ovate to ovate‐elliptic blade and distylous flowers.  相似文献   

18.
Based on field observation and specimen examination, a new species of Orchidaceae, Bulbophyllum nujiangense, is described and illustrated. Bulbophyllum nujiangense is closely related to B. cylindraceum in sect. Brachystachya in having tufted plants, large leaf, long inflorescence, small flowers in raceme, and fleshy lip, but can be easily distinguished from the latter in having flowers deep purplish red and whorl well spaced along the rachis, lateral sepals adhere to each other slightly at base, elliptic petals with obtuse and mucronate apex, lip deep purplish red.  相似文献   

19.
Geonoma atrovirens and G. supracostata (sect. Taenianthera ) (Arecaceae) from the western Amazon are described and illustrated. Both species are described on material hitherto included in the widespread G. macrostachys s.l., a species complex of understory palms represented in most parts of the Amazon region. Geonoma atrovirens resembles entire-leafed forms of Geonoma macrostachys var. macrostachys but differs form that taxon in having extremely narrow, bluish green leaves, and a different structure of its staminate flowers. Geonoma supracostata differs from all forms of G. macrostachys in the combination of an usually well developed aerial stem and moderately dissected leaves with the veins sharply raised alternately on the adaxial and the abaxial side of the lamina. A key to the species of Geonoma sect. Taenianthera in the western Amazon is provided.  相似文献   

20.
Floral nectar is thought to be one of the most important rewards that attract pollinators in Pedicularis;however,few studies have examined variation of nectary structure and/or nectar secretion in the genus,particularly among closely related species. Here we investigated nectary morphology,nectar quality,and nectar production dynamics in flowers of Pedicularis section Cyathophora. We found a conical floral nectary at the base of the ovary in species of the rex-thamnophila clade. Stomata were found on the surface of the nectary,and copious starch grains were detected in the nectary tissues. In contrast,a semi-annular nectary was found in flowers of the species of the superba clade. Only a few starch grains were observed in tissues of the semi-annular nectary,and the nectar sugar concentration in these flowers was much lower than that in the flowers of the rexthamnophila clade. Our results indicate that the floral nectary has experienced considerable morphological,structural,and functional differentiation among closely related species of Pedicularis. This could have affected nectar production,leading to a shift of the pollination mode. Our results also imply that variation of the nectary morphology and nectar production may have played an important role in the speciation of sect. Cyathophora.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号