Nelson Luiz Cosmo

Fruit and seed morphology and morpho-anatomy of seedlings of Vitex megapotamica (Spreng.) Moldenke (Lamiaceae)

Vitex megapotamica (taruma) e especie arborea, decidua, com ocorrencia, no Brasil, desde Minas Gerais ate o Rio Grande do Sul. Visando a caracterizacao morfologica do fruto, da semente e morfo-anatomica da plântula, frutos desta especie foram coletados e as sementes postas para germinar em laboratorio. As plântulas foram coletadas desde a protrusao da raiz ate o desenvolvimento do primeiro par de eofilo. Foram realizadas medicoes e pesagem de frutos, e contagem do numero de sementes por frutos. As caracteristicas morfologicas do fruto e da semente sao aqui descritas e ilustradas, assim como a morfo-anatomia da plântula. O fruto e drupoide, nuculânio, tetralocular, contendo apenas uma ou duas sementes com fina camada de endosperma e embriao axial, foliaceo. O diasporo (pirenio) e constituido pelo endocarpo mais a semente. O endocarpo lenhoso parece exercer restricao sobre a germinacao das sementes desta especie. A plântula e epigea, fanerocotiledonar, com paracotiledones elipticos, com margem inteira, e eofilos opostos, simples, elipticos, com margem serreada, apresentando tricomas tectores. Tanto o paracotiledone quanto o eofilo apresentam mesofilo heterogeneo, dorsiventral, feixe colateral em forma de arco e estomatos anomociticos. A raiz e poliarca, com cortex parenquimatico; o hipocotilo possui tricomas glandulares e nao-glandulares, colo distinto, e com cerca de 20 dias encontra-se em inicio de crescimento secundario. Diversas das caracteristicas da plântula de Vitex megapotamica estao relacionadas a sua condicao de especie heliofila.

Leaf Morphological Plasticity of Tree Species from Two Developmental Stages in Araucaria Forest

ABSTRACT This study compared the morphological and anatomical variations of the leaves of four shade-tolerant tree species Allophylus edulis (St.-Hil.) Radlk (Sapindaceae), Casearia sylvestris Sw. (Salicaceae), Cupania vernalis Cambess. (Sapindaceae) and Luehea divaricata Mart. (Malvaceae) from a fragment of Araucaria forest in two developmental stages. Morphological and anatomical traits, such as leaf and tissue thickness, leaf area, leaf dry mass, specific leaf area, leaf density and stomata density were measured from 30 leaves of each developmental stage. The phenotypic plasticity index was also calculated for each quantitative trait. The results showed that the four species presented higher mean values for specific leaf area and spongy/palisade parenchyma ratio at young stage, and higher mean values for stomata density, total and palisade parenchyma thickness in the adult stage. The plasticity index demonstrated that L. divricata presented highest plasticity for both the morphological and anatomical traits while A. edulis displayed the lowest plasticity index. The results of this study indicated that the leaves of these species exhibited distinct morphological traits at each stage of development to cope with acting environmental factors. Key words: leaf anatomy, leaf morphology, Ombrophyllous Mist Forest, shade tolerance

Influence of Guadua paraguayana Döll on the structure and regeneration of a remaining forest at the high lands of Tibagi River, Paraná state.

As soon as the bamboo’s invasion was diagnosed in the alluvial floodplain of Tibagi’s river, Ponta Grossa-PR, the study started evaluating, through phytosociological study and indicators associated with the structure and functioning of the forest, the aggression and influence of the bamboo species on the structure and regeneration of a subtropical ombrophilous alluvial forest remnant. The phytosociological study was developed by an installation of sixteen plots (50m2) to inventory all the trees with CBH ≥ 15 cm and sixteen other plots (4m2) for studying the regeneration: individuals with up to 1.30 m high. The results show that the effect of G. paraguayana in species richness, mortality and number of trees, vitality of the remaining trees, abundance of vascular and nonvascular epiphytes, regeneration and in the incidence of radiation inside the plots, is very significant. But even though the changes caused by this bamboo compromise the regeneration dynamics of alluvial formations in the high Tibagi’s areas, the species is only an aggravating and not the cause of environmental degradation.

Wood anatomy of Sebastiania commersoniana (Baillon) Smith & Downs (Euphorbiaceae): functional and ecological aspects

Sebastiania commersoniana is a very common tree species in alluvial environments with diverse soil conditions due to its plasticity and ability to tolerate periods of flooding. In this study we sampled 21 adult individuals of this species on the Iguacu River plain, for wood anatomy characterization and interpretation using a functional approach. S. commersoniana has diffuse porous, solitary vessels and multiples of two to six, radially arranged with simple perforation plates; low vessel frequency (12-16-20/mm2), with diameter of 54-88-117 µm, and vessel elements 164-602-1025 µm in length. The fibers are 656-1222-2050 µm in length, 10-26-42 µm wide, the walls are 1.0-2.8-5.1 µm thick. Fibers with a gelatinous layer are common. Apotracheal parenchyma diffusein-aggregates is found, while paratracheal parenchyma is scanty. Rays are uniseriate, 164-805-2787 µm tall and 12-22-35 µm wide. Perforated ray cells are frequent, as well as scar tissue containing starch grains. Starch also occurs in the radial and axial parenchyma. This species develops tension-wood in inclined trees. Most of the features observed coincide with available descriptions of the genus and family to which the species belongs. Some qualitative features are discussed on the base of possible roles and implications for species autoecology.