Floral structure in Licuala peltata (Arecaceae: Coryphoideae) with special reference to the architecture of the unusual labyrinthine nectary

The structure and late development of the flowers of the South‐East Asian bee‐pollinated palm Licuala peltata are described with special focus on the architecture of the unusual labyrinthine nectaries. The nectaries are derived from septal nectaries by extensive convolution of the carpel flank surfaces below the ovary throughout the inner floral base, thus also encompassing the inner surface of the corolla–androecium tube. A comparison with septal nectaries elsewhere in Arecaceae and with labyrinthine nectaries in other monocots shows that labyrinthine nectaries situated below the ovary, as described here, are not known from any other palms, but are similar to those of a few Bromeliaceae and, less strongly convoluted, some Haemodoraceae and Xanthorrhoeaceae. In addition, the substantial participation of parts other than the gynoecium in the nectary architecture of Licuala appears unique at the level of monocots. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 66–77.     

Floral morphogenesis in Sinofranchetia (Lardizabalaceae) and its systematic significance

The floral organs of Sinofranchetia chinensis Hemsl. (Lardizabalaceae) are all spiral in initiation. Stamen and petal (nectar‐leaf) primordia initiate independently and are different in shape. The petals and three stamens in the first whorl are retarded in the early developmental stages. The carpel primordia are conduplicate; the stigma is formed around the upper part of the ventral slit and the style is not differentiated. The functionally unisexual flowers are bisexual in organization in the early developmental stages. The development of the flowers on the inflorescence is spiral and centripetal. Some floral characteristics of Sinofranchetia appear to be plesiomorphic in Lardizabalaceae. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 82–92.     

采前喷钙对芍药切花生理生化的影响

以芍药切花品种'杨妃出浴'为试验材料,于采前不同时期喷施4%的CaCl2溶液,以不喷钙切花为对照,观察、测定芍药切花瓶插寿命、花径以及瓶插期间生理生化的变化,已探讨采前喷钙及喷钙时期对芍药切花衰老的影响.结果显示,采前喷钙处理有利于芍药切花保持水分平衡,增加切花花径和鲜重,降低切花体内可溶性蛋白质的降解速度,减缓膜透性的增大,延长切花寿命.研究表明,以采前21 d喷钙为最佳处理,可以延长芍药切花瓶插寿命2.3 d.     

The timing of food-deceptive flowers: a commentary on Internicola et al. (2008)

A recent article presents a study of pollinator visitation behaviour that is used to evaluate the selective pressure that pollinator visitation rate might have on the timing of the production of nonrewarding flowers. Here we take issue with the conclusions of the paper that there should be selection pressure for nonrewarding flowers to be available earlier in the season in order to avoid dissimilar sympatric rewarding species. Consideration of selection pressure must take into account temporal variation in total pollinator availability, pollinator longevity and unlearned response, and the stability of plant communities over time, as well as the learned responses of individual pollinators that the original study focused on. Learning alone would not necessarily select for early flowering by nonrewarders if temporal variation in pollinator numbers is strong or naïve pollinators consistently appear throughout the flowering season. Further, we argue that early flowering could simply be a natural corollary of longevity of flowers needed to combat negative frequency‐dependent selection and low overall visitation rates by pollinators, rather than a trait that has been specifically selected to reduce temporal overlap with competing rewarding species.     

Integrating Early Cretaceous fossils into the phylogeny of living angiosperms:Magnoliidae and eudicots

Over the past 25 years, discoveries of Early Cretaceous fossil flowers, often associated with pollen and sometimes with vegetative parts, have revolutionized our understanding of the morphology and diversity of early angiosperms. However, few of these fossils have been integrated into the increasingly robust phylogeny of living angiosperms based primarily on molecular data. To remedy this situation, we have used a morphological dataset for living basal angiosperms (including basal eudicots and monocots) to assess the most parsimonious positions of early angiosperm fossils on cladograms of Recent plants, using constraint trees that represent the current range of hypotheses on higher-level relationships, and concentrating on Magnoliidae (the clade including Magnoliales, Laurales, Canellales, and Piperales) and eudicots. In magnoliids, our results confirm proposed relationships of Archaeanthus (latest Albian?) to Magnoliaceae, Endressinia (late Aptian) to Magnoliales (the clade comprising Degeneria, Galbulimima, Eupomatia, and Annonaceae), and Walkeripollis pollen tetrads (late Barremian?) to Win-teraceae, but they indicate that Mauldinia (early Cenomanian) was sister to both Lauraceae and Hernandiaceae rather than to Lauraceae alone. Among middle Albian to early Cenomanian eudicots, we confirm relationships of Nelumbites to Nelumbo, platanoid inflorescences and Sapindopsis to Platanaceae, and Spanomera to Buxaceae. With the possible exception of Archaeanthus, these fossils are apparently not crown group members of living families but rather stem relatives of one or more families.     

Pollinator‐mediated selection in a specialized pollination system: matches and mismatches across populations

Most studies on pollinator‐mediated selection have been performed in generalized rather than specialized pollination systems. This situation has impeded evaluation of the extent to which selection acts on attraction or specialized key floral traits involved in the plant‐pollinator phenotypic interphase. We studied pollinator‐mediated selection in four populations of Nierembergia linariifolia, a self‐incompatible and oil‐secreting plant pollinated exclusively by oil‐collecting bees. We evaluated whether floral traits experience variable selection among populations and whether attraction and fit traits are heterogeneously selected across populations. Populations differed in every flower trait and selection was consistently observed for corolla size and flower shape, two traits involved in the first steps of the pollination process. However, we found no selection acting on mechanical‐fit traits. The observation that selection occurred upon attraction rather than mechanical‐fit traits, suggests that plants are not currently evolving fine‐tuned morphological adaptations to local pollinators and that phenotypic matching is not necessarily an expected outcome in this specialized pollination system.     

Somatic embryogenesis and plant regeneration from seeds of wild<Emphasis Type="Italic"> Dicentra spectabilis</Emphasis> (L.) LEM

Regeneration via somatic embryogenesis from callus was studied in Dicentra spectabilis. To obtain somatic embryogenic callus, we cultured D. spectabilis seeds on MS basal media supplemented with various concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D). The highest percentage of embryogenic callus formation was observed on media containing 1.0 mg/l 2,4-D under dark conditions. Somatic embryogenesis was studied by transferring the callus onto MS basal medium containing different concentrations (0.0, 0.1, 0.5, 1.0, 2.0 mg/l) of KIN (kinetin) and/or BAP. Somatic embryogenesis on MS basal media with 1.0 mg/l of KIN was excellent under light conditions. Somatic embryos were rooted by transferring them to half-strength MS basal media containing 2 g/l Phytagel. About 64.2% of the somatic embryos converted to rooted plantlets, 4% showed secondary embryogenesis and 31.8% did not develop and died. Rooted plantlets showed a 46% survival rate when acclimatized ex vitro.Abbreviations BAP 6-Benzylaminopurine - 2.4-D 2,4-Dichlorophenoxyacetic acid - KIN Kinetin - SEM Scanning electron microscopyCommunicated by H. Lörz     

Nectarless flowers: ecological correlates and evolutionary stability

In animal-pollinated flowers, the pollinators cannot detect the presence of nectar before entering flowers, and therefore flowers may cheat by not producing nectar. An earlier model suggested that a mixed strategy of producing nectarful and nectarless flowers would be evolutionarily stable. Here we compare nectarless flowers as a cheating strategy with three competing hypotheses namely "visit-more-flowers", "cross-pollination enhancement" and "better contact". We collected field data on 28 species of plants to test some of the differential predictions of the hypotheses. Nectarless flowers were detected in 24 out of 28 plant species. Correlations of percent nectarless flowers with floral and ecological variables support the cheater flower hypothesis. We further model the cost-benefits of cheating and show that an evolutionary stable ratio of nectarless to nectarful flowers can be reached. The equilibrium ratio is mainly decided by factors associated with pollinator density and pollinator learning.     

Flowering process in soybean under water deficit conditions: A review on genetic aspects

Soybean is a key crop in many countries, being used from human food to the animal industry due to its nutritional properties. Financially, the grain chain moves large sums of money into the economy of producing countries. However, like other agricultural commodities around the world, it can have its final yield seriously compromised by abiotic environmental stressors, like drought. As flowers imply in pods and in grains inside it to minimize damages caused by water restriction, researchers have focused on understanding flowering-process related genes and their interactions. Here a review dedicated to the soybean flowering process and gene network involved in it is presented, describing gene interactions and how genes act in this complex mechanism, also ruled by environmental triggers such as day-light and circadian cycle. The objective was to gather information and insights on the soybean flowering process, aiming to provide knowledge useful to assist in the development of drought-tolerant soybean lines, minimizing losses due to delays or anticipation of flowering and, consequently, restraining financial and productivity losses.     

Comparison of Diuraphis noxia resistance in wheat isolines and plant introduction lines

A bioassay to examine the foraging behaviour of the aphidophagous hoverfly, Episyrphus balteatus was used in which various stimuli purported to influence flower choice were tested using model flowers. In choice experiments, E. balteatus exhibited enhanced behavioural responses to the colour yellow, as previously seen in Eristalis by several workers. Previous suggestions that the generalist forager E. balteatus has no preference for colour are re-examined in the light of this new evidence. The other advertisement cue tested, size, was also demonstrated to play an important role in determining foraging behaviour, with the smaller artificial flowers seemingly preferred. Of the rewards tested, E. balteatus showed preference for the greatest nectar concentrations, whilst increasing pollen did not affect behaviour. These bioassays provided an opportunity to isolate the individual components of decision-making by E. balteatus during foraging. The separation of sexes and ages in these experiments permitted analysis of inter-sexual and inter-generation differences in behaviour, a factor apparently not investigated in previous work.