The reproductive biology of 13 South American taxa of Bothriochloa was studied. All surveyed species reproduce sexually and are self-compatible. Several elements also point to self-pollination as their main breeding system: (i) bud pollination that occurs in most species enhancing cleistogamy, (ii) presence of pits in the glumes that impede the opening of flowers and (iii) reduction in the number of stamens, a trend associated with outbreeding.
Helianthemum caput-felis is an endangered plant species growing in fragmented habitats in the western Mediterranean basin. Reproductive traits, breeding system and pollinator assemblage were studied in its largest known (mainland) European population to improve knowledge on the reproductive biology of the species. Hand-pollination experiments were carried out to determine the breeding system. Generalized linear mixed models (GLMM) were fitted to the data to evaluate the effect of treatment on fruit set and number of viable seeds per fruit. We also investigated the composition of the pollinator assemblage by direct observations, and studied their pollen load. Results were then compared to previous studies conducted in an island population. In the studied population, H. caput-felis is partially self-compatible, but mostly an outbreeder species, since outcrossed flowers produced many more fruits and seeds than self-pollinated ones. Conversely, pollination treatments did not affect reproductive output in the island population. We also found several differences between island and mainland composition of floral visitors, as it was expected. The study of pollen loads revealed that insects were mostly visiting H. caput-felis. Despite the low capacity to produce fruits with self-pollination, H. caput-felis presented no reproductive limitations in its main inland population. Reproductive characteristics along with differences among populations should be taken into account for adequate management and conservation practices. (C) 2015 Elsevier GmbH. All rights reserved.
Ranunculus weyleri is a species endemic to Mallorca Island (western Mediterranean basin) that is currently threatened due to its reduced geographical distribution and disjunct, isolated populations. It is a small, perennial herb that inhabits rocky environments, together with other endemic plants with creeping life-forms. In the present study, for the first time the reproductive biology of the species was investigated in terms of its floral phenology (floral stages and times of formation), pollen/ovule (P/O) ratios, and fruit and seed setting under natural and pollen manipulation experiments, assessing the breeding system, pollination vectors and pollen limitations. Cross-pollinations among populations were performed to evaluate the levels of compatibility between populations. In addition, the floral displays and the reproductive outputs of four wild populations were determined. The observed high P/O ratios, results of the hand-pollination experiments, and flower traits indicate that this species is predominantly allogamous. Combinations of both insects (belonging to Coleoptera, Diptera, Lepidoptera and Hymenoptera) and wind (ambophily) constitute the main pollination vectors, and pollen limitation was observed. Interpopulation crossing was effective, and exogamic depression was not present, as evidenced by the fecundity levels. The predation of the floral stems by herbivores (mainly goats) severely limits the reproductive success of this endemic species in wild populations. Finally, several ways of action are proposed for R. weyleri conservation.
Caesalpinia echinata (brazilwood) is a threatened tree endemic to the Brazilian Atlantic forest with a globalimportance as it is worldwide used to manufacture the most desirable bows for violins, violas, and cellos. Althoughthere is an international initiative for its conservation, there is a lack of studies on the reproductive biology of thespecies, as for the genus, a fundamental understanding for the conservation of any species. In this paper, weinvestigated the phenology, pollination, and breeding system of C. echinata, presenting some conservation guidelinesfor the species, together with a review of studies on the reproductive biology in Caesalpinia s.l. The genus has acomplex taxonomic history with recent attempts to reassign its limits. Pending a final resolution of the placing of somespecies (including C. echinata) our revision covers the traditional Caesalpinia s.l. and includes annotations indicating towhich segregate genus each species is now considered to belong, as well as the appropriate combination where this hasalready been published. Field work was undertaken from October/2004 to December/2006 at the Tapacura′ EcologicalStation, northeastern Brazil. Flowering occurred mainly in the dry season and the peak of seed dispersal was at thebeginning of the wet season. Anthesis is diurnal, lasting 1 day. The flowers are zygomorphic, yellow, sweet-scented, andthe effective pollinators were mainly medium-sized to large bees of the genera Centris and Xylocopa, together with theintroduced Apis mellifera. Nectar volume and sugar concentration averaged 2.971.0 mL and 29.579.4%, respectively.The ovary has 1–4 ovules (2.3570.58) and the pollen/ovule ratio was 5631.2; pollen viability was high (95.974.8%).Natural fruit set was low (9.2%) with mature fruits averaging 1.770.9 seeds. Results of the controlled pollinations andanalysis of pollen tube growth revealed C. echinata presents late-acting self-incompatibility. The pollination biologyand breeding system of C. echinata are discussed, together with available data on its genetics and physiology, in termsof best conservation practice for this endangered species. Data on the reproductive biology of the genus are scarce,revealing the predominance of bee pollination and SI system, with the occurrence of late-acting self-incompatibilitymechanisms in some species.
The reproductive system of Orchidaceae is predominantly xenogamous and highly dependent on animal pollen vectors. Nectar is the main floral resource, offered to pollinators in perigonal nectaries, cuniculi or spurs; these structures are often difficult to locate and to evaluate their functionality. The Neotropical Epidendrum denticulatum Barb. Rodr. and Epidendrum orchidiflorum Salzm. ex. Lindl. bloom synchronously throughout the year in the municipality of Marica (Rio de Janeiro State, SE Brazil). The flowers of E. denticulatum open in the morning, have a conspicuous pink colour, a nectar guide, and nuptial and extranuptial nectaries. During the day, they are visited by species of Hesperiidae (Lepidoptera), which remove the pollinia. The flowers of E. orchidiflorum open at night, are green with nuptial and extranuptial nectaries, and have a strong odour at night, suggesting nocturnal pollination agents, possibly moths. To date, no information is available on the reproductive biology and pollination mechanisms for E. orchidiflorum, nor is micromorphological, anatomical or histochemical data related to the presence and functionality of secretory structures associated with pollination in either species. Also, no studies have examined the occurrence of mechanisms that hinder or prevent interspecific pollination. Here, through reproductive, morphological, structural and histochemical analyses, we evaluated the floral biology and reproductive systems of these synchronopatric Epidendrum species. Both species have extranuptial nectaries, a functional cuniculus, and osmophores. Hand-pollination experiments revealed that the species are self-and intercompatible, although individuals with intermediate morphology were not identified. Pre-pollination barriers related to the floral biology of the species seem to be sufficient to prevent hybridization, but other biological aspects certainly contribute to the genetic integrity of the populations, such as the low rates of visits to
We studied the reproductive biology of Cipocereus minensis, an endemic columnar cactus of the Espinhago Mountain Range, Southeastern Brazil, focusing on floral biology, breeding system, and pollination. We described floral morphology and evaluated the role of nocturnal and diurnal pollinators on the reproductive success in two populations. C. minensis has large, horizontal, cream-colored, chiropterophilous flowers with rigid petals that open at dusk and close on the following morning. Flowers produced a huge amount of pollen grains and nectar production was nocturnal. Controlled pollination experiments revealed that the cactus is an obligate xenogamous species. Visitor-exclusion experiments revealed that the nocturnal visitors (bats) are the prominent pollinators whereas hummingbirds and social bees, which visited the flowers early in the morning, contributed little to fruit set. We conclude that the reproductive success of this endemic columnar cactus is threatened in the absence of the effective pollinating bats. (C) 2015 Elsevier GmbH. All rights reserved.
The pollination syndrome hypothesis predicts a direct relationship between a set of floral characters and the principal pollinating agent. The presence of flowers with poricidal anthers, heterostemony and pollen as the only reward are common traits in Melastomataceae species and are associated with buzz pollination by bees. Trembleya laniflora Cong. (Melastomataceae: Microlicieae) is an endemic species from campo rupestre tropical grassland, with large and white pollen flowers differing from the common purple-colored flowers of the Tribe. We examine the relationship between the distinct floral characteristics of T. laniflora and its pollination syndrome and reproduction ecology. We observed different individuals of T. laniflora randomly sampled in Serra do Cipo, Espinhaco Range, Minas Gerais, southeastern Brazil. We carried out observations on their reproductive phenology (31 individuals), flower biology (3), pollination (23), and tested the reproductive system (29). Trembleya laniflora presented a seasonal flowering pattern in the dry and post-dry seasons (MayOctober) and set fruits during the dry, post-dry and rainy seasons (June-December). Floral aperture occurred mainly during the night and the first hours of the morning, the period with the greatest availability of fresh flowers and with the highest visitation by Xylocopa bimaculata. Tests identified the species as non-apomictic, self-incompatible and dependent on large bees such as Xylocopa, Bombus, Centris and Ptiloglossa for pollination. Trembleya laniflora showed a specialized pollination system mediated by a restricted group of bees that perform crepuscular buzz pollination. Floral characteristics and reproductive biology of T. laniflora are likely adaptive responses to pollination by large bees foraging during the crepuscular hours. Our results support the pollination syndrome hypothesis, demonstrating a direct relationship between a set of floral characters and the principal pollinators of the species. D
Plant interactions with flower visitors are essential to understand the reproductive biology, evolution and distribution of flowering plants. Morphological convergences of flower traits have allowed flowers to maximize their attraction to pollinator agents leading to the concept of pollination syndromes. Due to habitat heterogeneity, low water retention and resource availability in the soil, as well as broad altitudinal range of the system, plants often show restricted distributions in rupestrian grasslands. The present study aimed to describe the floral biology and reproductive aspects of Collaea cipoensis, a shrub restricted to small patches alongside watercourses in rupestrian grasslands of Serra do Cipo, Brazil. Specifically, weexamined the dependence on pollinators to set fruits and the functional role of floral visitors (i.e. pollinators, nectar-robbers, nectar-thieves, and florivores). Collaea cipoensis is a strictly xenogamous species and two hummingbirds (Colibri serrirostris and Eupetomena macroura) are its potential pollinators. Although C. serrirostris also behaves as illegitimate visitor, it represents 90% of legitimate visits, thus being the most important pollinator. However, the most common flower visitors are two important nectar-robbers, the bee Trigona spinipes and the syrphid Toxomerus musicus. The species is self-incompatible and pollen-limited, as hand-pollination increased fruit production more than 50%. Still, hand-pollination set only 20% of fruits and 48% of seeds. Overall, the dependence on cross-pollination, the stressful environmental conditions and the high floral visitation rates by illegitimate visitors may limit reproduction of this species, leading to a fitness reduction. Our results reinforce the idea that rupestrian grasslands conforma complex scenario that restricts the species distribution. (c) 2017 Elsevier GmbH. All rights reserved.
Annual alien species are dependent on their sexual reproductive success to establish, maintain and spread their populations. As the annual exotic Impatiens balfourii (Balsaminaceae) is spreading in several temperate countries, we assessed its characteristics linked to sexual reproduction. The reproductive traits and the breeding system which could indicate some trends that might favour population spread and invasion were examined. Hand pollination treatments were performed under controlled conditions to evaluate (1) autonomous selfing ability, (2) self-compatibility and (3) inbreeding depression. Floral biology including morphology as well as nectar and pollen production was also assessed.
In Orchidaceae, nectar offering has been reported in many unrelated groups, including Oncidiinae. Among members of Oncidiinae, pollination by hummingbirds has been recorded for Comparettia in Central America, but nothing is known for the Brazilian species. The phenology, floral morpho-anatomy, production of floral rewards, pollinators, pollination mechanisms, and breeding system of Comparettia coccinea were investigated in a nature reserve in southeastern Brazil. The reddish flowers of C. coccinea produce nectar (volume 0.5-5 mu L, sugar concentration 17-28%) by two cylindrical glands located at the end of the labellum horns that can be accessed via two nectary entrances. The studied species is exclusively visited and pollinated by Nymphalidae butterflies and flower features, such as color, symmetry and morphology, support the occurrence of psychophily in C coccinea. Pollinaria are attached to the butterfly eyes during the collection of nectar from the spur. When a butterfly visits the right nectar entrance, pollinaria are deposited on its left eye and vice versa. The species is self-compatible and depends on a biotic pollen vector to set fruits. This is the first record of effective pollination by butterflies in Oncidiinae. (C) 2015 Elsevier GmbH. All rights reserved.