Morphological evolution in the graminid clade: Comparative floral anatomy of the grass relatives Flagellariaceae and Joinvilleaceae

New comparative data are presented on the reproductive morphology and anatomy of two genera closely related to grasses, Flagellaria and Joinvillea, in which the flowers are superficially similar, especially in stamen morphology. This investigation demonstrates some anatomical differences between the two genera. For example, both genera depart from the 'typical' condition of tepal vasculature (three-traced outer tepals and one-traced inner tepals): in Flagellaria, each tepal receives a single vascular bundle and, in Joinvillea, each tepal is supplied by three vascular bundles. Joinvillea possesses supernumerary carpel bundles, as also found in the related family Ecdeiocoleaceae, but not in Flagellaria or grasses. In the anther, the tapetum degenerates early in Flagellaria, and is relatively persistent in Joinvillea, in which the pollen grains remain closely associated with the tapetum inside the anther locule, indicating a correlation between peripheral pollen (a feature that is common in grasses) and a persistent tapetum. This study highlights the presence of a pollen-tube transmitting tissue (PTTT) or solid style in the gynoecium of Flagellaria, as also in many Poaceae, but not in Joinvillea or Ecdeiocoleaceae. We speculate that the presence of a PTTT could represent one of the factors that facilitated the subsequent evolution of the intimately connected gynoecia that characterize grasses. © 2012 The Linnean Society of London.

Anatomia floral de espécies de Cyperaceae (Poales)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ecologia da polinização de Eschweilera nana Miers, uma Lecythidaceae do cerrado

Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

Floral anatomy of Bromeliaceae, with particular reference to the evolution of epigyny and septal nectaries in commelinid monocots

Floral anatomy is described in ten genera of Bromeliaceae, including three members of subfamily Bromelioideae, three Tillandsioideae, and four genera of the polyphyletic subfamily Pitcairnioideae (including Brocchinia, the putatively basal genus of Bromeliaceae). Bromeliaceae are probably unique in the order Poales in possessing septal nectaries and epigynous or semi-epigynous flowers. Evidence presented here from floral ontogeny, vasculature, and the relative positions of nectary and ovules indicates that there could have been one or more reversals to apparent hypogyny in Bromeliaceae, although this hypothesis requires a better-resolved phylogeny. Such evolutionary reversals probably evolved in response to specialist pollinators, and in conjunction with other aspects of floral morphology of Bromeliaceae, such as the petal appendages of some species. The ovary is initiated in an inferior position even in semi-epigynous or hypogynous species. The ovary of all so-called hypogynous Bromeliaceae is actually semi-inferior, because the septal nectary is infralocular; in these species the nectaries have a labyrinthine surface and many vascular bundles. Brocchinia differs from most other fully epigynous species in that each carpel is secretory at the apex and reproductive, rather than secretory, at the base.

Morphology, development and homologies of the perianth and floral nectaries in Croton and Astraea (Euphorbiaceae-Malpighiales)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Differentiation of floral color and odor in two fly pollinated species of Metrodorea (Rutaceae) from Brazil

We investigated if differences in morphological characters in two species of Metrodorea (Rutaceae) from Brazilian semideciduous forests correspond to some pollination divergence. M. nigra and M. stipularis are sympatric species, display a similar floral morphology, are protandrous, self-incompatible, their flower periods overlap, and both are pollinated by flies. M. nigra main pollinators are Pseudoptiloleps nigripoda (Muscidae) and Fannia sp. (Fanniidae); M. stipularis major pollinators are Phaenicia eximia (Calliphoridae), Palpada sp. and Ornidia obesa (Syrphidae). The distinct floral odor (disagreeable in M. nigra and sweet in M. stipularis) and color (brownish violet vs. pale yellow) determine the differences on type and number of floral visitors observed. Several species from semideciduous forests initially considered to be pollinated by diverse insects, present flies as main pollinators, stressing the importance of fly pollination in such habitats.

The taxonomic value of floral characters in Rapateaceae (Poales-Monocotyledons)

The floral anatomy of Cephalostemon, Monotrema, Rapatea, Spathanthus, and Stegolepis was studied for taxonomic purposes. All species studied share colleters between the floral parts; sepals, petals, anthers, and style covered by an ornamented cuticle; short epidermal cells with sinuous walls on the abaxial surface of the petals; tetrasporangiate anthers with phenolic idioblasts in the epidermis; endothecium with spiral thickenings; incompletely septate ovary; and anatropous, bitegmic ovules. The floral anatomy is useful not only for characterizing the family, but also for delimiting the subfamilies and genera. Sepals with silica bodies in the epidermal cells; mature anther wall composed of epidermis, endothecium, and middle layer; absence of phenolic idioblasts in the sepals, filaments, and ovary; and stylar epidermal cells with thickened external periclinal wall support Rapateoideae. Cephalostemon and Rapatea show a great number of similarities, corroborating their close relationship indicated in the phylogenetic analyses of the family. Monotrema shares few characters with the genera of Rapateoideae, corroborating its placement in Monotremoideae. Stegolepis shows several distinctive characters, probably related to the greater diversity found in this genus. © 2012 Springer-Verlag Wien.

Anatomy of the floral nectaries of some neotropical Salacioideae (Celastraceae)

Floral nectaries have contributed to the systematics of different taxonomic groups. Since those of the neotropical genera included in subfamily Salacioideae-Cheiloclinium Miers, Peritassa Miers, Salacia L. and Tontelea Aubl.-have different forms and positions, we explored their anatomy to delimit more precisely the genera of subfamily Salacioideae. Buds and open flowers of six species were treated following the usual techniques in plant anatomy. The obtained data were helpful in characterizing the floral nectary anatomy of the studied species. Furthermore, some features such as form, position and surface of nectaries; form of their epidermal cells; presence and distribution of stomata; occurrence of idioblasts containing druses in the nectariferous parenchyma; and absence of nectary vascularization can contribute to the taxonomy and phylogeny of the Salacioideae studied. In most of the studied species the nectar is probably released by both the stomata and the nectary epidermal surface. In Cheiloclinium cognatum, the structure acknowledged as nectary is actually a vestigial tissue and the functions of attracting and rewarding pollinators has phylogenetically migrated to the stigmatic region. The druses and phenolic substances observed in the nectariferous parenchyma probably help defend flowers against herbivore attacks. The minute size of the nectaries of Salacioideae may explain the absence of vascularization. The floral nectaries of Salacia elliptica are epithelial while those of the other species are mesenchymal. © 2012 Springer-Verlag Wien.

Evaluation of the floral vasculature of the Janusia, Mascagnia and Tetrapterys species as a tool to explain the decrease of floral organs in Malpighiaceae

The family Malpighiaceae is considered monophyletic, but the intra-family classification is conflicting. Analyses of floral vasculature allow the identification of reductions, connations and adnations and can even reveal evolutionary steps prior to current floral morphology. The present work analysed the floral vasculature of Janusia mediterranea, Mascagnia cordifolia and Tetrapterys chamaecerasifolia using material processed by traditional methods for light microscopy. A general pattern was observed of three bundle traces supplying each sepal and one trace per petal and stamen; Mascagnia is an exception, as its eglandular sepal has only a median trace but shares lateral traces with adjacent sepals. No dorsal traces are emitted to the carpels; however, three intercarpellary complexes are emitted that divide into six ventral bundles, supplying the ovule. Mascagnia demonstrates connation between the anterior and adjacent sepal glands; reductions of the anterior sepal glands were registered in Tetrapterys and Janusia. This work reveals two distinct processes for gland loss in non-related groups of the family that resulted in similar present appearances. Our evaluation of the number of calyx glands and the processes of glandular loss in species with less than ten glands improves our understanding of the evolution of calyx glands in Malpighiaceae. © 2013 Elsevier GmbH.

The systematic significance of floral morphology, nectaries, and nectar concentration in epiphytic cacti of tribes Hylocereeae and Rhipsalideae (Cactaceae)

A long-standing interest in cactus taxonomy has existed since the Linnaean generation, but an appreciation of the reproductive biology of cacti started early in the 1900s. Numerous studies indicate that plant reproductive traits provide valuable systematic information. Despite the extensive reproductive versatility and specializations in breeding systems coupled with the striking floral shapes, the reproductive biology of the Cactaceae has been investigated in approximately 10% of its species. Hence, the systematic value of architectural design and organization of internal floral parts has remained virtually unexplored in the family. This study represents the most extensive survey of flower and nectary morphology in the Cactaceae focusing on tribes Hylocereeae and Rhipsalideae (subfamily Cactoideae). Our objectives were (1) to conduct comparative morphological analyses of flowers and floral nectaries and (2) to compare nectar solute concentration in these two tribes consisting of holo- and semi-epiphytic species. Flower morphology, nectary types, and sugar concentration of nectar have strong taxonomic implications at the tribal, generic and specific levels. Foremost, three types of nectaries were found, namely chamber nectary (with the open and diffuse subtypes), furrow nectary (including the holder nectary subtype), and annular nectary. All Hylocereeae species possess chamber nectaries, in which the nectarial tissue has both trichomes and stomata. The Rhipsalideae are distinguished by two kinds of floral nectaries: furrow and annular, both nectary types with stomata only. The annular nectary type characterizes the genus Rhipsalis. Nectar concentration is another significant taxonomic indicator separating the Hylocereeae and Rhipsalideae and establishing trends linked to nectar sugar concentration and amount of nectar production in relation to flower size. There is an inverse relationship between flower size and amount of nectar production in the smaller Rhipsalideae flowers, in which nectar concentration is more than two-fold higher despite the smaller volume of nectar produced when compared to the large Hylocereeae flowers. Variability of nectary morphology and nectar concentration was also evaluated as potential synapomorphic characters in recent phylogenies of these tribes. In conclusion, our data provide strong evidence of the systematic value of floral nectaries and nectar sugar concentration in the Cactaceae, particularly at different taxonomic levels in the Hylocereeae and Rhipsalideae. © 2013 Perspectives in Plant Ecology, Evolution and Systematics.

Órgãos reprodutivos em Hylocereeae e Rhipsalideae (Cactaceae): morfologia floral e desenvolvimento estrutural do fruto e da semente

Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

Development and evolution of the gynoecium in Myrteae (Myrtaceae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)