台闽苣苔（苦苣苔科）花部器官的形态发生

在扫描电镜下对台闽苣苔 (T .oldhamii (Hemsl.)Solereder)进行了花部器官形态发生的观察 ,为探索该类群的个体发育、类群间的系统发育关系和进化趋势提供依据。研究发现该属植物萼片、花冠和雄蕊发生式样均为五数花类型 ,它们各自来源于花原基上分化出来的萼片原基、花冠原基和雄蕊原基 ;花冠与雄蕊的两侧对称性与花冠上唇生长稍快和退化雄蕊原基发育迟滞相关 ;萼片原基的发生和发育的顺序是不一致的 :萼片原基发生的式样为近轴中原基—远轴 2原基— 2侧原基 ,发育式样则为近轴中萼片— 2侧萼片—远轴 2萼片 ,花蕾时为镊合状排列。花冠裂片原基的发生和发育式样是一致的 ,即远轴中裂原基 (下唇中裂片 )—远轴 2侧裂原基 (下唇 2侧裂片 )—近轴 2裂原基 (上唇 2裂片 )。花蕾期卷迭式为覆瓦状排列 ,从外向内 :下唇中裂片—下唇 2侧裂片—上唇 2裂片或下唇 2侧裂片—上唇 2裂片—下唇中裂片。雄蕊原基与花冠裂片原基互生 ,前方雄蕊原基在发生上稍迟于后方雄蕊原基 ,后者与退化雄蕊原基几乎同时发生 ,但较小 ,并与近轴心皮 (或柱头上唇 )对生。将该属与玄参科 (Scrophulari aceae)的地黄属 (Rehmannia)、苦苣苔科 (Gesneriaceae)的异叶苣苔属 (Whytockia)和尖舌苣苔属 (Rhynchoglossum)的花部器官比较发现     

广西苦苣苔科唇柱苣苔属一新种——李氏唇柱苣苔

报道了在广西柳州市市区附近一岩溶洞穴发现的苦苣苔科唇柱苣苔属一新种,并命名为李氏唇柱苣苔。本种与寿城唇柱苣苔及百寿唇柱苣苔相近,与寿城唇柱苣苔的主要区别在于植株体形、叶和花较大,叶为长卵状椭圆形或椭圆形,叶缘具锯齿,每花序1-3花,退化雄蕊3而与之不同;与百寿唇柱苣苔的区别主要在于叶缘具锯齿,每花序仅1-3花,花药背部密生紫色髯毛,退化雄蕊3而不同。     

台闽苣苔(苦苣苔科)花部器官的形态发生

在扫描电镜下对台闽苣苔 (T. oldhamii (Hemsl.) Solereder)进行了花部器官形态发生的观察,为探索该类群的个体发育、类群间的系统发育关系和进化趋势提供依据.研究发现该属植物萼片、花冠和雄蕊发生式样均为五数花类型,它们各自来源于花原基上分化出来的萼片原基、花冠原基和雄蕊原基;花冠与雄蕊的两侧对称性与花冠上唇生长稍快和退化雄蕊原基发育迟滞相关;萼片原基的发生和发育的顺序是不一致的:萼片原基发生的式样为近轴中原基-远轴2原基-2侧原基,发育式样则为近轴中萼片-2侧萼片-远轴2萼片,花蕾时为镊合状排列.花冠裂片原基的发生和发育式样是一致的,即远轴中裂原基(下唇中裂片)-远轴2侧裂原基(下唇2侧裂片)-近轴2裂原基(上唇2裂片).花蕾期卷迭式为覆瓦状排列,从外向内:下唇中裂片-下唇2侧裂片-上唇2裂片或下唇2侧裂片-上唇2裂片-下唇中裂片.雄蕊原基与花冠裂片原基互生,前方雄蕊原基在发生上稍迟于后方雄蕊原基,后者与退化雄蕊原基几乎同时发生,但较小,并与近轴心皮(或柱头上唇)对生.将该属与玄参科(Scrophulariaceae)的地黄属( Rehmannia )、苦苣苔科(Gesneriaceae)的异叶苣苔属( Whytockia)和尖舌苣苔属(Rhynchoglossum )的花部器官比较发现,这四个属在这方面呈现出多样性和交叉.过去一直按子房室数和胎座类型划分玄参科(子房2室、中轴胎座)和苦苣苔科(子房1室、侧膜胎座)这一做法受到了质疑.     

中国广西苦苣苔科一新种--灵川小花苣苔

报道了在广西岩溶洞穴发现的苦苣苔科Gesnenaceae小花苣苔属Chiritopsis一新种——灵川小花苣苔C．lingchuanensis Yah Liu＆Y.G.Wei。本种因聚伞花序花稀疏,花冠白色,明显二唇形,上唇比下唇短3倍以上,退化雄蕊3而与羽裂小花苣苔C.bipinnatifida W .T．Wang相近,区别在于前者叶不裂,雄蕊被短柔毛。本种在叶形上还与小花苣苔C.repandaw T.Wang相近,不同在于后者花冠不明显二唇形,上下唇近等长,雄蕊无毛,退化雄蕊2。灵川小花苣苔的分布范围狭窄,目前仅见于一个岩溶洞穴的近洞口段,具明显的洞生习性。     

广西苦苣苔科一新属——文采苣苔属

描述了在广西发现的苦苣苔科一新属和一新种,即文采苣苔属Wentsaiboea D. Fang & D. H. Qin及文采苣苔W. renifolia D. Fang & D. H. Qin, 并提供墨线图。文采苣苔属的柱头外形略似长檐苣苔属Dolicholoma D. Fang & W. T. Wang, 不同在于前者叶肾形,基部心形,具掌状脉,花冠斜钟状,裂片圆形,雄蕊和退化雄蕊着生于冠筒近基部。新属在体态上还接近小花苣苔属Chiritopsis W. T. Wang, 但前者叶具掌状脉,冠筒钟状,远轴侧膨胀,柱头马蹄形;在后者叶具羽状脉,冠筒筒状,不膨胀,柱头下唇倒梯形至线形。     

台闽苣苔(苦苣苔科)幼苗的发育式样及其意义

为解决台闽苣苔族(Titanotricheae)这一单种族的科级系统位置,通过扫描电镜观察了台闽苣苔( Titanotrichum oldhamii (Hemsl.) Solereder)植物的种子发芽和幼苗发育过程.随着下胚轴的向下伸长,两个子叶开始不明显的异率生长,其中一片子叶略大于另一片子叶.但两片子叶均正常发育并位于同一高度.当真叶发出后,两片子叶几乎等大,并且两个子叶柄等长.在幼苗生长期间,随着子叶的生长,胚芽也正常萌发出茎的顶芽.顶芽持续进行顶端生长产生交互对生的真叶.这一幼苗生长式样和苦苣苔亚科其他类群的仅一片子叶发育与胚芽被抑制的幼苗生长式样有明显区别.考虑到台闽苣苔植物在总状花序的上部大量簇生无性珠芽,并落地迅速生长出新的植株这一在苦苣苔科中独特的无性繁殖方式及相关性状,台闽苣苔族可能较早地从苦苣苔亚科中分化出来,并在繁殖体的功能进化方面和其他类群发生歧化进而获得独特的无性繁殖方式.台闽苣苔族在系统发育上应该被认为是其他苦苣苔亚科类群的姊妹群,应当提升为亚科等级.     

台闽苣苔（苦苣苔科）幼苗的发育式样及其意义

为解决台闽苣苔族 (Titanotricheae)这一单种族的科级系统位置 ,通过扫描电镜观察了台闽苣苔 (Titan otrichumoldhamii (Hemsl.)Solereder)植物的种子发芽和幼苗发育过程。随着下胚轴的向下伸长 ,两个子叶开始不明显的异率生长 ,其中一片子叶略大于另一片子叶。但两片子叶均正常发育并位于同一高度。当真叶发出后 ,两片子叶几乎等大 ,并且两个子叶柄等长。在幼苗生长期间 ,随着子叶的生长 ,胚芽也正常萌发出茎的顶芽。顶芽持续进行顶端生长产生交互对生的真叶。这一幼苗生长式样和苦苣苔亚科其他类群的仅一片子叶发育与胚芽被抑制的幼苗生长式样有明显区别。考虑到台闽苣苔植物在总状花序的上部大量簇生无性珠芽 ,并落地迅速生长出新的植株这一在苦苣苔科中独特的无性繁殖方式及相关性状 ,台闽苣苔族可能较早地从苦苣苔亚科中分化出来 ,并在繁殖体的功能进化方面和其他类群发生歧化进而获得独特的无性繁殖方式。台闽苣苔族在系统发育上应该被认为是其他苦苣苔亚科类群的姊妹群 ,应当提升为亚科等级。     

苦苣苔科镜像花的多样性及演化

泛热带分布的苦苣苔科(Gesneriaceae)在我国南方具有极高的物种丰富度与特有率,花部特征变化丰富,是研究物种形成与适应演化的代表类群。镜像花(mirror-image flowers)是极为特化的传粉系统,在苦苣苔科中出现了较多的不同类型,可能与苦苣苔科物种多样性形成与维持有关。该研究总结与分析了苦苣苔科镜像花的类型多样性以及系统分布与适应演化等,讨论了镜像花对苦苣苔科物种形成与维持的积极意义。结果表明:镜像花仅分布在亚洲和非洲的苦苣苔亚科(Didymocarpoideae)的7个属,在历史上就至少发生了5次独立起源。长冠苣苔属(Rhabdothamnopsis)、南洋苣苔属(Henckelia)及长蒴苣苔属(Didymocarpus)镜像花的花柱与可育雄蕊分别向左、右两侧偏转,形成互补镜像花;蛛毛苣苔属(Paraboea)、喜鹊苣苔属(Ornithoboea)、非洲堇属(Saintpaulia)镜像花缺乏与花柱对应侧偏的可育雄蕊(非互补镜像花);而海角苣苔属(Streptocarpus)直立堇兰亚属(subg.Streptocarpella Engler)则同时出现了互补、非互补镜像花。不同于其他被子植物(离瓣花、缺乏花冠筒),苦苣苔科中的镜像花大多伴随着明显的花冠筒、内藏的雄蕊、合生的花药,以非互补镜像花为主;传粉者以小型的无垫蜂(Amegilla spp.)和熊蜂(Bombus spp.)为主。这些特殊的花部综合征与特化的传粉机制,提高了传粉精确性,可能促进了传粉隔离与物种适应辐射。今后的一个研究重点应通过分子系统发育方法,进一步揭示苦苣苔亚科互补与非互补镜像花的进化顺序及其在物种分化与长距离扩散过程中的可能作用。     

中国喜鹊苣苔属(苦苣苔科)一新记录种——雷氏喜鹊苣苔

报道了中国苦苣苔科(Gesneriaceae)喜鹊苣苔属(Ornithoboea Parish ex C.B.Clarke)一新记录种——雷氏喜鹊苣苔(O.lacei Craib),该种与滇桂喜鹊苣苔(O.wildeana Craib)近似,其区别特征在于花冠下唇裂片顶端凹陷,退化雄蕊3。凭证标本存放于广西植物研究所标本馆(IBK)。     

广西苦苣苔科稀有珍贵植物——弥勒苣苔

首次报道广西苦苣苔科植物一新记录属:弥勒苣苔属.该属接近金盏苣苔属,但不同在于弥勒苣苔属花冠上唇4浅裂,下唇不分裂,2对雄蕊分别着生于花冠中部及其上方,雌蕊具一个柱头.弥勒苣苔属为中国特有的单型属,仅弥勒苣苔一种,分布于云南东南部和广西西部.该种在广西首次记录,凭证标本存放于广西植物标本馆(IBK).     

Patterns and Significance of Floral Development in Whytockia (Gesneriaceae)

Abstract: The floral development of Whytockia W. W. Smith has been studied in order to explore the developmental basis for the arrangement and differentiation patterns of floral organs, and the evolutionary relationship between Whytockia and allies in floral development. The descending imbricate aestivations in both calyx and corolla have remarkably different ontogenetic patterns between calyx and corolla which are derivative with respect to the development of the valvate aestivations in the four-stamened Rhynchoglossum. Both corolla lobes and stamens are initiated simultaneously from the same ring meristem. However, the five stamens remarkably precede the initiation of the five corolla lobes. Also, the adaxial stamen is suppressed after initiation to become a staminode, concomitant with retardation of its adjacent organs during development. This situation, together with the non-acropetal order among whorls of floral organs in Whytockia, is possibly related to a late expression and a remarkably different expression pattern of cycloidea- like genes as compared to Antirrhinum. Furthermore, the axile placentation in the bilocular ovary of Whytockia is formed by an involute closure of carpels rather than derived from a secondary fusion of two intrusive parietal placentae.     

SPIRAL DEVELOPMENTAL PATTERNS IN THE STEM AND INFLORESCENCE OF LILIUM TIGRINUM

Extensive correlations in spirality were observed among vegetative and floral organs in Lilium tigrinum Ker. Organs involved were vegetative leaves, bracts, and bracteoles. These correlations varied in their degree of constancy depending upon the organs involved. The mature inflorescences of L. tigrinum appeared to fit the common definition of a raceme. In 67.3% of the flowers at node 3 on the raceme, the bract-bracteole spirals reversed the spiral of vegetative leaves on the stem. These reversals resembled those observed on essentially cymose inflorescences of certain members of the Caryophyllaceae. Cymose branching was found to be an invariable feature of the inflorescence of L. tigrinum when secondary flowers appear. The apparently indeterminate tips of inflorescence main axes were interpreted as exhibiting stages in progression from a basically determinate (cymose) inflorescence. It was concluded that the ancestors of L. tigrinum had well-developed cymose branching patterns in the inflorescence. Reversal of stem spirals by the bract-bracteole spirals at the apices of many inflorescences was considered to be the result of complete utilization of the inflorescence meristem. Explanations for those reversals were provided by the field theory and by the theory of the first available space.     

A model for studying pollination and pod development in Brassica napus: the culture of isolated flowers

Summary A technique for cultivating isolated flowers of Brassica napus has been developed. Flowers were harvested at anthesis, the surface of their peduncles was then sterilized and they were cultivated in a hormonefree medium. We used an MS medium supplemented with 3% sucrose as a source of organic carbon. From our experiments, it was concluded that no exogenous growth regulator is required to ensure normal growth and development in vitro. The flowers, and thereafter the pods, can be kept in culture until seed maturity. After 30 days, seed development resulted in three types of seeds: (1) normal, (2) milky and (3) aborted. The results show that the number of seeds per pod was not dependent on the order of flowers on the raceme (except the first 10 flowers and flowers above row 50). Our study supports the validity of this model as an easy tool for studying pollination and early seed development.     

Development and Control of the Number of Flowers per Node in Pisum sativum L.

Non-dormant flower initials are laid down in the axils of successiveleaf initials as they are formed by the apical meristem of Pisumsativum L. In cultivars with a maximum capability of two flowersper raceme, the undeveloped flower meristem divides into twoportions. One forms the first flower and the other either developsinto a small protrusion on one side of the first flower or becomesthe second flower, depending on the prevailing environment.Flower development in conditions favouring single-flowered racemeswas advanced by one plastochron. Variation in the number offlowers per raceme occurs between cultivars and between environments.The number of double flowers formed was favoured by higher lightintensity (120 Js^–1 m^–2) and carbon dioxide concentration(330 µ11^–) and lower temperature (15°C). Incultivars producing more than two flowers per raceme, lowerlight intensity (60 Js^–1 m^–2) plus higher temperature(20°C) increased the mean number of flowers per raceme.Soluble sugar levels in all varieties were higher (36.05 mgeq glucose g^–1 fresh weight) in the low temperature/highlight environment than the high temperature/low light environment(14.80 mg eq glucose g^–1 fresh weight). The flowering potential and stability of 13 cultivars have beenassessed in controlled environment and in sowing date trialsin the field. A stable variety, which consistently producedtwo flowers per raceme, was identified in controlled environmentand its stability was maintained in field trials. A linear regressionof stability of flower number in the field on stability in controlledenvironment accounted for 89.6 per cent of the variance (P<5per cent), but the flowering potential in a sowing date experimentwas not related to temperature or radiation intensity.     

RE-EVALUATION OF CERTAIN KEY RELATIONSHIPS IN THE ALISMATIDAE: FLORAL ORGANOGENESIS OF SCHEUCHZERIA PALUSTRIS (SCHEUCHZERIACEAE)

Transition to flowering in the North-temperate bog plant Scheuchzeria palustris occurs in early May and results in the formation of a simple raceme with six flowers. Five of the flowers are subtended by large foliar bracts, while the sixth and last-formed flower on the inflorescence remains ebracteate. The individual flowers develop along a clearly trimerous pattern. The three outer tepals develop first, arising almost simultaneously at the periphery of the triangular floral apex. They are followed closely by the development of the three anti-tepalous outer stamens. The three inner tepals are next in the developmental sequence, alternating with the outer whorl of tepal-stamen pairs but arising at a slightly higher level on the floral meristem. Three inner stamens are initiated opposite the inner tepal primordia. Finally, three gynoecial primordia are initiated on the remaining central portion of the floral apex and alternating with the inner whorl of tepal-stamen pairs. Each carpel develops at first as a horseshoe-shaped structure. Two ovules form in each carpel, initiating on the adaxial margin of the carpel wall. Histogenesis of all floral appendages involves initially periclinal divisions in the second tunica layer followed by corresponding anticlinal divisions in the first tunica layer and concurrent activity in the underlying corpus. Separate procambial strands differentiate acropetally from the inflorescence axis to each tepal-stamen pair and then bifurcate. The vascular connection to the gynoecium develops directly from the strands in the tepal-stamen pairs. The results of this developmental study of the flower of S. palustris have a significant bearing on the positioning of this and related taxa within the Alismatidae and on the speculation of the phylogeny of the monocotyledon flower.     

Resource availability regulates reproductive meristem activity, development of reproductive structures and seed set in buckwheat (Fagopyrum esculentum)

Grain yields in buckwheat ( Fagopyrum esculentum ) are consistently low despite a profuse and long-lasting flowering. The mechanisms underlying this reproductive failure are still largely unknown. In this study, performed in strictly controlled conditions, the possible implication of assimilate availability in the regulation of the reproductive development was investigated in the 'La Harpe' cultivar, by manipulating sink/source relationships through excisions of selected leaves and/or selected inflorescences and hand pollinations of selected and precisely identified flowers. Increasing or decreasing source/sink organ ratio in buckwheat, respectively, enhanced or reduced the production of racemes by the shoot apical meristem and of cymes by the racemes, ultimately modulating the number of flowers per plant. The effect on seed production was essentially indirect and related to flower production. Seeds developing on a plant also affected reproductive morphogenesis, limiting flower production. Three stages at which flower development to mature seed may fail have been identified. First, an abnormal morphogenesis resulted in flowers with an undersized and sterile gynoecium. Secondly, after anthesis, numerous flowers with a normal sized gynoecium, were unable to develop a seed after hand pollination. Finally, a small proportion of flowers exhibited a later abortion of the seed. Flower fate is dependent on position in the raceme and time of opening: chance to develop normally and produce a ripe seed is higher for flowers at the base than at the top of the inflorescence. A mechanism, internal to the raceme, regulates flower fate, independently of assimilate availability. This mechanism may be disturbed by drastic reductions in nutrient supply.     

Temporal and spatial regulation of symplastic trafficking during development in Arabidopsis thaliana apices

Plasmodesmata provide symplastic continuity linking individual plant cells. However, specialized cells may be isolated, either by the absence of plasmodesmata or by down regulation of the cytoplasmic flux through these channels, resulting in the formation of symplastic domains. Maintenance of these domains may be essential for the co-ordination of growth and development. While cells in the center of the meristem divide slowly and remain undifferentiated, cells on the meristem periphery divide more frequently and respond to signals determining organ fate. Such symplastic domains were visualized within shoot apices of Arabidopsis, by monitoring fluorescent symplastic tracers (HPTS: 8-hydroxypyrene 1,3,6 trisulfonic acid and CF: carboxy fluorescein). Tracers were loaded through cut leaves and distributed throughout the whole plant. Confocal laser scanning microscopy on living Arabidopsis plants indicates that HPTS moves via the vascular tissue from leaves to the apex where the tracer exits the phloem and moves symplastically into surrounding cells. The distribution of HPTS was monitored in vegetative apices, and just prior to, during, and after the switch to production of flowers. The apices of vegetative plants loaded with HPTS had detectable amounts of tracer in the tunica layer of the meristem and in very young primordia, whereas the corpus of the meristem excluded tracer uptake. Fluorescence signal intensity decreased prior to the onset of flowering. Moreover, at approximately the time the plants were committed to flowering, HPTS was undetectable in the inflorescence meristem or young primordia. Later in development, after several secondary inflorescences and mature siliques appeared, inflorescence apices again showed tracer loading at levels comparable to that of vegetative apices. Thus, analysis of fluorescent tracer movement via plasmodesmata reveals there is distinct temporal and spatial regulation of symplastic domains at the apex, dependent on the developmental stage of the plant.     

STRUCTURAL AND HISTOLOGICAL STUDIES OF THE CAMBIUM AND SHOOT MERISTEMS OF SOYBEAN TREATED WITH 2,3,5-TRIIODOBENZOIC ACID

Flowering soybeans were sprayed at the tips with 50 ppm TIBA. Microscopic and macroscopic observations were made of the nodes, internodes, and shoot meristems every week for 4 wks after TIBA treatment. TIBA-treated plants produced open flowers at the upper nodes 1 week earlier than did control plants. Accompanying this early flower development, the following changes occurred in the upper internodes, as compared to controls: (a) increased activity of the procambium; (b) rapid development of thick-walled protophloem cells; (c) production of small vessels. Three weeks after treatment middle internodes of treated plants showed less cambial activity than did corresponding internodes of controls. The changes in the middle internodes of treated plants suggest a close correlation with increased flowering. Two weeks after treatment some lateral shoot apices at nodes nearest the main shoot apex exhibited the following changes, in contrast with controls: (a) development of conical apices with stack-of-brick-like peripheral cells; (b) shrinkage of protoplasmic contents in some rib meristem cells and young pith cells; (c) frequent thickening of primary walls in young pith cells. Three weeks after treatment cells of lateral shoot meristems with conical axillary buds showed a denser stain for protein than did cells of corresponding meristems of controls. Floral apices in these meristems also stained more densely for protein than did similar apices in control plants. Together with early flower production in the upper nodes of treated plants, less starch occurred 2–3 weeks after treatment than in corresponding nodes of controls. Two to three weeks after treatment lateral shoot apices of both treated and control plants had numerous, large starch grains in the rib meristem, young pith, leaf and bud primordia, and developing flowers but few starch grains appeared in the tunica, corpus, and procambium.