Pollination biology and breeding system of Zeyheria montana (Bignoniaceae)

The reproductive biology of Zeyheria montana was studied through field observations of flower visitors and floral events, controlled manual pollinations, and observations of pollen tube growth and ovule penetration by fluorescence microscopy. Analysis of secretory areas of the nectar chamber was made by flower dissections and histology of serial sections. The flower lasted 6–8 days, but pollen exposure and stigma receptivity occurred only up to the end of the first and second days, respectively. Pollination was effected by several species of hummingbirds, especially Colibri serrirostris. The flowers present a rudimentary, non-functional disc, and secretion of nectar is performed by corolla-borne glandular trichomes. Only hand cross-pollinated and natural-pollinated flowers set fruits. Artificially self-pollinated and non-pollinated flowers dried off after anthesis without presenting any swelling of the ovary. Almost all the ovules in selfed and crossed pistils were penetrated 96 h after pollination. However, a delay in ovule penetration in self-pollinated pistils was verified, which indicates the occurrence of late-acting self-incompatibility.We are grateful to Fundo de Apoio ao Ensino e à Pesquisa (UNICAMP) for financial support, and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for the fellowship granted to the first author (this work is part of a Ph.D. thesis presented to UNICAMP, Campinas, SP, Brazil).     

蓝花丹结实率低的传粉生物学和繁育系统初探

为解释蓝花丹自然结实率低的原因,该研究从传粉生物学和繁育系统入手,采用TTC法与联苯胺-过氧化氢法分别测定花粉活力和柱头可授性的动态变化;用花粉-胚珠比(P/O比)、杂交指数(OCI)估算蓝花丹繁育系统类型并通过人工控制授粉试验验证。结果表明:(1)蓝花丹L型雌器官与S型雄器官、L型雄器官与L型雌器官成熟时间重叠区域较多,雌雄性器官在成熟时间上无显著差异;而S型雌器官与L型雄器官、S型雌器官与S型雄器官成熟时间重叠区域较少,但蓝花丹持续开花的模式缓解了雌雄性器官时间差异而引起的生殖隔离。(2)蓝花丹L型花P/O为502.00±52.30,S型花P/O为482.70±87.91,OCI为4,综合判断蓝花丹的繁育系统属于专性异交型且具有异型自交不亲和的特性。综上可初步解释蓝花丹自然结实率低的原因为内外因素共同作用的结果,其中雌雄性器官同熟时间短不是主要原因,而其本身较强的自交不亲和性可能是自然结实率低下的关键性内因。由于蓝花丹的专性异交繁育系统使其成功授粉需要传粉媒介,但因引种地与原产地环境存在显著差异,同时开花模式不集中导致的缺乏传粉者完成异花授粉或许是引起异交成功率降低的主要外因。因此,提高蓝花丹的结实率应从克服其自身自交不亲和性以及适当引入安全传媒昆虫入手。     

珍稀濒危植物距瓣尾囊草(Urophysa rochkii)的开花物候和繁育系统特性

通过野外观察,运用套袋授粉和联苯胺-过氧化氢法等实验方法对距瓣尾囊草开花物候以及种群的繁育系统特性进行研究。研究结果:1)距瓣尾囊草为两性花,聚伞状花序,花期较长,从头年12月持续到次年4月,单花花期持续8—15 d,种群花期可持续4个月左右。2)距瓣尾囊草在花朵未开放前花粉没有活力,花药开裂当天花粉活力达到94.8%,第2天为90.3%,第3天为81.6%,第4天为62.9%,此后其花粉活力明显减弱;柱头可授性于散粉后第3天开始出现,散粉后4—5天最强,散粉后第8天柱头失去可授性;柱头可授性和花粉活力有5 d左右的重叠期。3)其花粉胚珠比P/O为938.5±250,按照Cruden标准划分,其有性繁育系统为兼性异交。4)按照Dafni的标准,距瓣尾囊草的OCI=4,即繁育系统为异交、部分自交亲和、需要传粉者。5)人工异花授粉结实率达80%以上,略高于自然结实率78.94%;直接套袋结实率为5.71%;去雄套袋和去雌套袋均不结实。以上结果表明,距瓣尾囊草繁育系统表现为异交为主、部分自交亲和并且不存在无融合生殖现象,其开花物候、花部特征和繁育系统为适应特殊的环境提供了一定的生殖保障,本次研究结果为距瓣尾囊草的迁地保护和种群的繁衍复壮提供理论依据。     

西南银莲花(毛茛科)地理分布的订正—特别基于花粉形态证据

通过标本检查和花粉扫描电镜观察,发现过去鉴定为西南银莲花(Anemone davidiiFranch.)(毛茛科)的我国西藏东南部(墨脱)标本实际上属于三出银莲花(A. griffithiiHook. f.& Thoms.),所以以前关于西南银莲花产西藏东南部的记载是错误的。西南银莲花目前仅发现分布于我国重庆(城口、南川、武隆、巫溪、酉阳、云阳)、贵州(江口、凯里、雷山)、湖北(神农架、兴山、宣恩、竹溪)、湖南(桑植、石门、新宁)、四川(安县、宝兴、都江堰、峨边、峨眉、洪雅、金阳、筠连、雷波、马边、石棉、天全、通江、荥经)和云南(大理、墨江、维西、中甸)。     

Variation in the breeding system of two sympatricDombeya species on La Réunion island

The high frequency of dioecy on oceanic islands has attracted a great deal of attention in plant evolution. In this study we quantify variation in the breeding system of two sympatricDombeya species on La Réunion island. BothDombeya species are cryptically dioecious, each sex retaining non-functional morphological structures of the other sex. One species is strictly dioecious, whilst the other shows leaky dioecy, with 8/13 males producing fruit during two years of study. Males that set fruit did so following outcrossing but not after self-pollination despite the growth of self-pollen tubes in the style. This suggests the occurrence of a late-acting self-incompatibility system. Several morphologically intermediate individuals are recognized and suggested to be a result of interspecific hybridization. These purported hybrids are hermaphrodite and self-compatible, consistent with a complementary breakdown in dioecy and self-compatibility.     

蛛网萼开花物候、花部特征及繁育系统研究

为探讨蛛网萼(Platycrater arguta)传粉生物学特性,该研究以江西上饶广丰铜钹山国家级自然保护区、江西阳际峰国家级自然保护区蛛网萼为材料,采用野外观察和人工授粉等方法,对蛛网萼开花物候、花部形态及繁育系统进行了研究。结果表明:(1)蛛网萼为伞形花序,种群花期一般在6月中下旬至8月中旬,单花花期为2~3 d,花序花期持续10 d。两个保护区由于年均温度与光照的不同,花期进程有显著不同。(2)蛛网萼可孕花与不孕花从绿色变为白色时对访花昆虫有吸引作用,不孕花能够增加昆虫的访花频率。(3)蛛网萼花粉胚珠比(P/O)为2 520~3 100,杂交指数即是3或4。(4)繁育体系属于以异交为主,部分自交亲和,需要传粉者;熊蜂(Bombus sp.)、四条蜂(Apis florea)和油茶地蜂(Andrena cammelia)是蛛网萼的有效传粉昆虫。(5)套袋和人工授粉结果显示,蛛网萼为兼性自交和异交授粉,异株异花授粉能显著提高坐果率及结籽率,这主要与生境中有效传粉昆虫种类、数量少,花粉传递效率低,种群间基因流交流降低以及柱头自花及同株异花传粉等有关,从而表明在蛛网萼现有生境中植株的早期生殖成功受到影响。蛛网萼种群分布范围扩张以有性繁殖为主,无性繁殖作为重要补充及繁殖保障。     

矮紫金牛的开花生物学与繁育系统研究

矮紫金牛(Ardisia humilis)是优良的野生观赏植物。为探究该植物开花生物学与繁育系统特征,促进其杂交选育与园林应用,该研究以同质园引种的矮紫金牛为对象,对其开花物候、访花昆虫种类及访花行为进行观测,采用花粉离体萌发法和联苯胺-过氧化氢法,对花粉活力与柱头可授性进行检测,结合配子显微观测法和控制性授粉实验,对其繁育系统进行分析。结果表明：(1)花期为5月中下旬至6月中上旬,盛花期在5月底,单花、单株和群体水平的花期分别为1、17～20、25 d。(2)开两性花,雌蕊先熟,与雄蕊成熟期部分重叠,柱头可授性滞至雄蕊凋谢后1 d。(3)杂交指数(OCI)值为4,花粉/胚珠比(P/O)值为5.61×10³,显示其繁育系统以异交为主,部分自交亲和,需要传粉者。(4)自然授粉的结实率最高(平均52.96%),其次是自花授粉(52.29%)和人工异株授粉(50.33%),三者差异不显著(P> 0.05),但均显著高于人工同株授粉的结实率(28.67%)(P<0.05),显示矮紫金牛不仅异交亲和性强,还具有很强的自动自花授粉能力。(5)主要传粉昆虫包括隧蜂科...     

Pollination ecology in sympatric winter flowering Helleborus (Ranunculaceae)

We studied biotic and abiotic factors that influence pollination in two sympatric winter flowering species. Helleborus foetidus and Helleborus bocconei flower simultaneously in winter. Although climatic conditions are not favorable for biotic pollination both species rely mainly on large bees of the genus Bombus. At the beginning of flowering, harsh climatic conditions are restrictive for insect visits. As flowering continues and temperatures rise, pollinator activity increases. The two plant species share pollinators that visit them indiscriminately. The flowers of the two species differ in form and insects visit H. foetidus by inserting their heads and H. bocconei ventrally: pollen load on insects is highly specialized. With the arrival of spring, many other species start to bloom and in spite of the large number of flowers still on the plants insects abandon Helleborus species. At the end of spring increasing biotic interactions take away pollinators from the Helleborus species.     

The breeding system ofEmblingia (Emblingiaceae)

Emblingia is a short lived fire weed with a highly autogamous breeding system.     

Floral development in Adonideae (Ranunculaceae)

Floral development and floral phyllotaxis in species of Adonis, Callianthemum, and Trollius (Ranunculaceae) were studied with scanning electron microscopy. The floral organs are initiated in spiral sequence and the flowers have spiral phyllotaxis. The sepal primordia are broad, crescent-shaped, and truncate, but those of petals, stamens, and carpels are rather hemispherical. A relatively long plastochron appears to be present between the last sepal and the first petal as compared with the short and equal plastochrones of all subsequent floral organs. Maturation of the stamens within the androecium appears to be centripetal. The carpels have a short ascidiate zone. Placentation is uniformly lateral, even in Adonis and Callianthemum, which have only one fertile ovule per carpel (versus median in other genera of Ranunculoideae with a single fertile ovule). In Adonis and Callianthemum at the tip of the carpel the ventral slit is gaping and the stigma is broadly exposed, whereas in Trollius the stigma is narrower and more pronouncedly decurrent along the ventral slit. The petals in Callianthemum and Trollius are more conspicuously delayed in development than those in Adonis as compared with sepals and stamens. A short carpel stipe is formed early in Callianthemum but later in Adonis and Trollius. In Trollius farreri (commonly having only five carpels in contrast to other species of Trollius) the carpels form a single (spiral) series. Thus floral development is similar in all three genera and, at a lower level, Adonis and Callianthemum are especially close but have different autapomorphies, which reflects the current classification of the genera.     

The effects of phosphorus nutrition and soil pH on the growth of some ancient woodland indicator plants and their interaction with competitor species

The forest under-storey herbs Anemone nemorosa, Lamiastrum galeobdolon and Veronica montana are generally considered indicator species of old, broadleaved woodland sites where the soil fertility is often low. In a glasshouse bioassay, however, all three species not only showed large positive growth responses to supplied P concentrations (0–10mgL ^–1) solutions, but also tolerated high P concentrations (20–40mgL ^–1), well above those normally found in their natural habitat. Plants responded by raising the concentrations of P in their shoot and root tissues and increasing their biomass, resulting in an increased P uptake. A shade-tolerant competitor species, Urtica dioica, also grew vigorously across the full range of P concentrations, restricting the growth of the woodland species. This emphasises the difficulty of establishing semi-natural woodland vegetation in the presence of competitor species, for example in situations where new woodlands are planted on fertile ex-agricultural soils containing large residual concentrations of P. The influence of soil pH on the growth and nutrient relations of A. nemorosa, L. galeobdolon, V. montana, Poa trivialisandU. dioicawas determined in a separate experiment using an ex-arable soil as the growing medium with pH levels adjusted from 7.4 to 5.8 and 4.3 respectively. Acidifying the soil enhanced growth, but reduced the concentrations of N, P and K in the leaves of all three woodland species, probably due to dilution of these minerals in the increased dry matter production. The competitor species (P. trivialis and U. dioica) responded in similar manner to the woodland indicator species. These results suggest that manipulating soil pH as a means of facilitating the establishment of woodland indicator species in new farm woods is unlikely, in the short term, to be effective where competitor species are present.     

Life cycle and growth ofTrichostegia minor (Curtis) in temporary woodland pools (Trichoptera: Phryganeidae)

Larvae of the caddisTrichostegia minor (Curtis) were collected from four woodland pools in The Netherlands, three of which are temporary, from August 1986 till June 1987. Eggs and larvae of this species proved to be very well adapted to drought, freezing, strongly fluctuating pH and alkalinity levels and prolonged oxygen deficit. The life cycle ofT.minor in a small woodland marsh overgrown byCalla palustris took one year. Adult flight period started at the end of May. Oviposition took place independent of water. Hatching of the eggs started in September and was probably induced by immersion. During the larval stage from September until May, 5 instars could be distinguished by the size of the head capsule. Growth of instars I, II and III during autumn was moderate. Most larvae overwintered as instar III or IV. Possibly there was a larval diapause during winter. In spring rapid growth to instar V took place prior to pupation. Growth rate, expressed as the increase of mean individual dry weight was highest from March to April (2.05±0.75% DW.m^–2.d^–1). In extremely shallow water growth in spring was initially more rapid compared to growth in deeper water. During winter the growth rate decreased to 0.038±0.071% DW.m^–2.d^–1. Net annual production based on the changes of momentary biomass was 183.2±31.7 mg DW.m^–2.y^–1 or 177.2±31.3 mg AFDW.m^–2.y^–1. Production loss during the winter season was 75.1±10.8 mg DW.m^–2.y^–1 or 72.3±10.6 mg AFDW.m^–2.y^–1.     

姜科、闭鞘姜科植物繁育系统与传粉生物学的研究进展

综述了姜科Zingiberaceae植物繁育系统和传粉生物学方面的研究及其进展。姜科有50余属1500多种,是一个泛热带分布的、动物传粉的单子叶植物大科。姜科植物中存在着雌花两性花异株、雄花两性花同株、花柱卷曲性、雄性先熟、自交不亲和等多种性表达方式和花部机制。姜科植物重要的传粉动物包括各种蜂类、天蛾、蝴蝶、鸟类等,不同的传粉动物对应不同的花部特征。在相对有限的研究中,姜科植物展现出了一些独特的传粉和繁育机制,在豆蔻属Amomum、山姜属Alpinia等植物中发现的花柱卷曲性被认为是植物界中一种独特的促进异交的行为机制,在对黄花大苞姜Caulokaempferia coenobialis的研究中发现了植物界中一种全新的花粉滑动自花传粉机制,这些新的研究和发现丰富了我们对姜科植物传粉和繁育系统多样性的认识。本文提出了今后姜科植物繁殖生物学研究的建议:对更多未知姜科植物类群的传粉和繁育系统进行研究;从系统发育的角度开展姜科不同类群植物的传粉和繁育系统的演化研究;对花柱卷曲性这一独特的性多态现象开展全面深入的研究。     

Variation in wild populations of annual beet (Beta,Chenopodiaceae)

Among the morphological variation in wild annual populations of sect.Beta only tepal characters show a geographic pattern, and hence can be used to distinguish different taxa. Two morphological types correspond with taxa already described:B. macrocarpa (incl.B. bourgaei) has a Macaronesian and W. to E. Mediterranean andB. adanensis an E. Mediterranean distribution area. A third type in the Aegean region is not well known yet and possibly has to be included inB. macrocarpa. Both diploid and tetraploid (x = 9) cytotypes are found withinB. macrocarpa, the latter exclusively on the Canary Islands.     

四川毛茛科二新种——乌头属一新种和唐松草属一新种

该文描述了自四川西部发现的毛茛科二新种,包括四川乌头属一新种,即泸定乌头(Aconitum ludingense W.T.Wang),此新种隶属于乌头属乌头亚属,以及四川唐松草属一新种,即狭药唐松草(Thalictrum stenantherum W.T.Wang),给出了此新种与其近缘种六脉萼唐松草之间的形态区别.     

Effect of the breeding system on the genetic structure in threeCephalanthera spp. (Orchidaceae)

The genetic variation of seven enzymes for a total of nine loci was investigated in three species of terrestrial orchids of the genusCephalanthera:C. longifolia, C. rubra, andC. damasonium. These species are characterized by presenting different breeding types: outbreeding , outbreeding with facultative vegetative reproduction, and inbreeding, respectively. Electrophoretic evidence points to a difference in the behaviour of each of the three species which seems strictly related to the breeding type. On the basis of our resultsC. longifolia behaves as a normal outbreeder, whileC. rubra presents the influence of vegetative reproduction in some populations and not in others.C. damasonium shows a total lack of both among and within populations genetic variation, which is most probably due to the autogamic breeding type.     

Cytotaxonomische Untersuchungen in der Artengruppe desRanunculus alpestris (Ranunculaceae)

Morphological and cytological investigations as well as crossing experiments were carried out with the 5 species of theRanunculus alpestris group (R. alpestris L.,R. traunfellneri Hoppe,R. bilobus Bertol.,R. crenatus Waldst. etKit.,R. magellensis Ten.). A key to the species is presented; localities and distribution are given in addition to extensive diagnoses. Crossing experiments between the 5 taxa were successful (F₁-F₃ individuals, backcross types, tripeland quadrupelbastards); the morphology of the experimentally obtained F₁-hybrids was mostly intermediate. All 5 species as well as all hybrids have a chromosome number of 2n = 16; there is no statistically significant difference between the karyotypes of the 5 taxa. According to the results of the morphological investigations and the crossing experiments we can distinguish 2 subunits of very closely related species: a)R. alpestris, R. traunfellneri, R. bilobus; b)R. crenatus, R. magellensis. The speciation within the group ofRanunculus alpestris is discussed.

     

Genetic diversity and phenotypic variation in marginal populations of the locally endangered speciesHordeum secalinum (Poaceae)

Electrophoresis was used to compare variation in hordein polypeptide patterns and isozymes in five marginal populations ofHordeum secalinum (four Swedish and one Danish population) and four populations along the Atlantic coast from Denmark to Spain. Hordein patterns were uniform within and among Swedish and Danish populations whereas the materials from France and Spain were divergent. The banding patterns for nine isozymes (AAT, IDH, MDH, PGD, GPI, ME, ACP, EST, and PRX) agreed with those reported for otherHordeum species. All putative loci were monomorphic with the exception of PRX, which showed three different phenotypes. The five marginal populations varied in seed set and cultivated plants differed in phenological traits.Dedicated to emer. Univ.-Prof. DrFriedrich Ehrendorfer on the occasion of his 70th birthday     

Floral sexuality and breeding system in gum karaya tree, Sterculia urens

Comprehensive studies were carried out on phenology, floral sexuality, pollination biology, pollen-pistil interaction, breeding system and fruit and seed set on three populations of gum karaya tree (Sterculia urens). The species is andromonoecious and produces a large number of male and a limited number of bisexual (functionally female) flowers. The numbers of male and bisexual flowers varies not only between trees but also during the flowering period within a tree. Each male flower produces about 5000 fertile pollen grains. Neither in morphology nor in number, is there any difference between pollen grains in the bisexual and male flowers. However, pollen grains of bisexual flowers are completely sterile and incapable of siring any seeds. Their anthers, however, serve to attract pollinators; the emasculated bisexual flowers fail to do so. Thus S. urens is apparently andromonoecious but exhibits cryptic monoecy. That the species is self-incompatible was confirmed by controlled pollinations. The self-incompatibility is of the late-acting type and manifests after the entry of the pollen tube into the ovule. Apis indica is the only pollinator recorded by us and wind plays no role in pollination. The efficacy of pollination is low as only 56% of flowers were estimated to be pollinated. The pollen load on one-third the number of pollinated stigmas was lower than the number of ovules present. Fruit set under open pollination is poor and is highly variable from tree to tree (0.7–3.2%). Apart from pollination constraint, limited resource availability may also contribute to low fruit set.     

Sex expression in EgyptianThymelaea hirsuta (Thymelaeaceae) populations

The sex expression inThymelaea hirsuta was assessed in five habitats in the western Mediterranean desert of Egypt. The survey over two main flowering periods indicated that the sexual expression of this plant is complex and labile. Beside the dioecious male and female states, five monoecious states were detected. The dioecious states are more abundant and less labile. There is a clear shift from monoecious towards dioecious states and in general favour of males from the first (late autumn) to the second (late winter) flowering period. These results are discussed in view of the adaptive theories and evolution.