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Bat pollination occurs in about 250 genera in 67 plant families and is clearly a derived pollination mode in most plant lineages. Fleming et al. (pp. 1017–1043) examine this mode from a phylogenetic perspective and discuss reasons why plants might want to use energetically expensive bats as their pollen dispersers. They propose that flower-visiting bats provide two important benefits to plants: they deposit large amounts of pollen and a variety of pollen genotypes on plant stigmas and, compared with many other pollinators, they are long-distance pollen dispersers.
The Charophycean green alga, Chara corallina, undergoes a rapid and complex differentiation process during production of multicellular antheridia. Domozych et al. (pp. 1045–1056) use a combination of approaches including immunobinding and ultrastructural analyses to identify cell wall polymers during antheridium development. Many polymers common to embryophyte cell walls are recognized although specific distribution patterns in inclusive ‘tissues’ are found to vary.
Submergence-induced shoot elongation is an essential trait for plants from habitats with shallow, prolonged flooding. Chen et al. (pp. 1057–1067) find variation in this trait both among and within populations of the wetland species Rumex palustris, but this is independent of habitat type. Spatio-temporal variation in flooding may have contributed to the maintenance of this genetic variation in elongation responses. (Featured article in ContentSelect on p. v.)
Conservation measures too often have to be taken without all the desirable genetic information being available. Lorenzo et al. (pp. 1069–1076) illustrate the usefulness of genetic surveys for assessing conservation priorities and strategies in marginal populations, focusing on cork oak, Quercus suber, in the Balearic Islands as a case study. Despite the limited population, the oaks show very high genetic diversity and structure, which should influence the planning of conservation efforts for this endangered species.
Orchids are renowned for their showy, colourful flowers and their specialized interactions with insects; however, pollinator attraction is sometimes primarily mediated by the floral scent, particularly in species that lure their pollen vectors by the false promise of sex. Vereecken and Schiestl (pp. 1077–1084) investigate how perianth colour and floral scent influence pollinator visitation rates in the sexually deceptive species Ophrys arachnitiformis and find that chemical signals alone can mediate the interactions in this highly specialized mimicry system. (Featured article in ContentSelect on p. v.)
In C4 species, high vein density is adaptive and essential for C4 photosynthetic functioning. A leaf development study of C3 and C4 Flaveria by McKown and Dengler (pp. 1085–1098) shows that this shift is achieved primarily through accelerated and earlier offset of minor vein formation, and that the characteristic high vein density in C4 species results from changes in the number of minor veins formed.
Legumes have a great diversity in flower morphology and petal types. Ojeda et al. (pp. 1099–1110) perform a survey of the petal micromorphology of the three types of petals within the family and provide a classification of the epidermal types. They discuss the association of these epidermal types with petal identity, patterns of its evolution and links with their genetic and developmental basis.
In the Amazonian floodplains, plants withstand annual periods of flooding that can last 7 months. Ferreira et al. (pp. 1111–1119) study Himatanthus sucuuba, a tree species found in contrasting floodplain and adjacent non-flooded forest environments (terra firme and várzea populations). They suggest divergent evolution is critical to survival, with larger carbohydrate allocation to germination in non-flooded populations whereas those subject to flooding allocate comparatively more to carbohydrates mobilized during seedling development.
AtSUC2 encodes the predominant Suc/H+ symporter involved in phloem loading and is essential for efficient phloem transport and growth. However, Srivastava et al. (pp. 1121–1128) demonstrate that plants homozygous for a null allele (Atsuc2-4) complete their life cycle and produce viable seed. Arabidopsis thus appears to have mechanisms for mobilizing reduced carbon from sites of photosynthesis to developing seeds independent of AtSUC2. (Featured article in ContentSelect on p. vi.)
Cucumis melo subsp. agrestis (Cucurbitaceae) is cultivated in many African regions for its edible kernels. Kouonon et al. (pp. 1129–1139) study the evolution and maintenance of andromonoecy in this species and find it to be fully self-compatible, with very low inbreeding depression. However, the species is self-infertile and insect-mediated pollination is essential for reproductive success. The role of male flowers could be linked to limitation of pollen transfer.
Oils are an unusual floral reward found in the Orchidaceae and are produced by elaiophores; they have been described in a few species of Oncidiinae. Aliscioni et al. (pp. 1141–1149) identify the presence of elaiophores in the labellar callus of Gomesa bifolia and find them to be of the epithelial type. The oil appears to pass through the outer tangential wall and the cuticle, covering the latter without forming cuticular blisters.
The rate of plant decomposition depends on both the decomposition environment and the functional traits of the individual species (e.g. leaf and litter quality), but their relative importance in determining interspecific differences in litter decomposition remains unclear. By studying 17 herbaceous species representative of three stages of a Mediterranean succession, Kazakou et al. (pp. 1151–1161) demonstrate that species litter decomposability is affected by some leaf and litter traits but not by soil nitrogen supply.
Lotus tenuis is a forage legume of increasing importance in areas prone to soil waterlogging, or shallow to complete submergence. Manzur et al. (pp. 1163–1169) show that L. tenuis is able to change its growth strategy depending on the degree of plant submergence. Either an escape strategy based on promoted shoot elongation or a quiescence strategy based on consumption of stored reserves is selected depending on whether plants are partially or completely submerged. (Featured article in ContentSelect on p. vi.)
Flowering and fruit production of oil palm, Elaeis guineensis, show seasonal maxima whose causes are unknown. Legros et al. (pp. 1171–1182) study phenological and growth responses of adult oil palms and suggest that even near the equator seasonal peaks of flowering in oil palm are controlled by photoperiod response within a phytomer. These patterns are confounded with drought effects that affect flowering (yield) with a long time-lag.
Despite its simple architecture and small phenotypic plasticity, oil palm (Elaeis guineensis) has complex phenology and source–sink interactions. Legros et al. (pp. 1183–1194) use fruit pruning to determine that although sink limitation results in an increase in the rate of development and the proportion of female inflorescences, the low plasticity of plant architecture limits compensatory growth. Non-structural carbohydrate storage is thus the main adjustment process.
Masting, or synchronized intermittent reproduction, is a common phenomenon among tree species; however, underlying physiological mechanisms such as resource allocation are unclear. In Betula grossa, Ishihara and Kikuzawa (pp. 1195–1205) find that masting causes annual variation in shoot demography and leaf area, and resource-allocation models may thus benefit from incorporation of this variation in masting species.
There is a need for relatively easy-to-use phenotyping tools for breeding programmes aimed at improving drought adaptation in C4 crops such as maize. Cabrera-Bosquest et al. (pp. 1207–1216) compare the use of ash content with the stable isotopes Δ13C and Δ18O in assessing yield potential of Zea mays. They find that ash content in leaves and kernels proves a useful alternative or complementary criterion to Δ18O in kernels for assessing yield performance in maize grown under drought conditions.
Based on pre-existing data from quadrat surveys and information from published floras, Meng et al. (pp. 1217–1229) analyse changes within six plant morphometric traits along gradients of growing season temperature and plant water availability in northern China, and find that all traits show clear patterns along the gradients. This opens the possibility of using quadrat- and flora-based trait analyses to examine climate–trait relationships in other regions of the world.
Using nuclear and chloroplast microsatellite markers, Andrianoelina et al. (pp. 1231–1242) analyse the impact of fragmentation on 18 populations of Dalbergia monticola, an endangered tree species in Madagascar. They find a high diversity, an absence of a bottleneck, a pattern of isolation by distance and a moderate differentiation among populations, which suggest a weak genetic signal of fragmentation that could be due to the small number of D. monticola generations since its establishment on the island.
Decaisnea is a monotypic genus of Lardizabalaceae, and its embryology has only been subject to one study, over 50 years ago. Wang et al. (pp. 1243–1253) re-examine early embryological events in D. insignis, and determine that pollen is shed when 3-celled, not 2-celled, as previously reported, and that endosperm formation is nuclear. These two characters are not found in any other members of Lardizabalaceae, leading to the suggestion that Decaisnea needs elevation in taxonomic status above the level of genus.