Microgramma

Abstract: A B S T R A C T Investigation of the development and organography of the shoot systems of Microgramma vacciniifolia and M. squamulosa was undertaken for the purpose of determining: (1) the features of shoot growth that are responsible for the distinctive vining character of these epiphytic ferns; and (2) the mode of origin of branches and their contrast with leaf initiation. Shoots of both species are dorsiventral and plagiotropic (i.e., parallel to the substrate) in habit. Since the shoot apical meristem is radial in transectional symmetry, shoot dorsiventrality in Microgramma is a postgenital or secondary developmental event, and its inception is related to the initiation of lateral appendages. Leaves and buds arise in a distichous phyllotaxis and occupy opposite and alternating positions on the dorsal surfaces and flanks of the rhizome. Endogenous roots are initiated in two rows from the ventral surface of the stem, in the vicinity of the rhizome meristem; however, they do not emerge from the rhizome until some distance behind the tip and do not elongate until the region of substrate contact. We conclude that the vining nature of this fern rhizome is a result of precocious internodal elongation and the concomitant delay of leaf and bud expansion in the region of stem elongation. In addition, observation of branch origin confirms previous suggestions that branching in Microgramma is strictly lateral and extra-axillary and not a dichotomous derivative as proposed by some workers. Leaf and bud primordia differ not only in the nature of their respective vascular supplies but also in their actual course of initiation. In the case of the leaf, the primordium is precociously emergent and exhibits a lenticular apical cell at its summit when it is only one plastochron removed from the flanks of the apical meristem. By contrast, initials of the bud primordium divide less actively and remain in a sunken position for at least 5-6 plastochrons; only when the bud apex becomes expanded and emergent does a tetrahedral apical cell become recognizable at the tip of the bud promeristem. Because of the distinctive pattern of branch and leaf origin, as well as the lack of adventitious and phyllogenous origin of branch primordia, we suggest that the shoot of Microgramma is a useful test organism for the re-examination of the problem of leaf and bud determination in the ferns.

Abstract: In this paper is presented the taxonomic treatment for the species of Polypodiaceae from the west border of Brazilian Pantanal. The family is represented by 14 species, corresponding to the genera Pecluma (four species), Pleopeltis (three species), Campyloneurum, Microgramma and Phlebodium (two species each), and Serpocaulon (one specie). Identification keys, descriptions of genera and species, illustrations, geographic distribution, and comments on the closest species are presented.

Abstract: Thi s wor k pre sent s a flori sti c survey o f the pterido phyte s (Lycophyta e Monilo phyta ) o f the Parque Ambiental of Belem in the Municipality of Belem, State of Para. This Park is part of the a Environmental Protected Area, representing one of the last relatively conserved forest remnants in Belem metropolitan area. Through collections realized from October 2002 to January 2004, 18 families, 30 genera and 49 species were recorded. The families with the largest number of species were Polypodiaceae and Hymeno phylla ceae , both with six specie s, folo wed by the Pterida ceae , with fi ve specie s. The mostre - presentative genera were Trichomanes L., with fi ve specie s, folo wed by Cyathea Sm., Microgramma C. Presl, Thelypteris Schmidel, Nephrolepis Schott and Lindsaea Dryand, with three species each. Of the 49 species recorded for the area, two are new references for the State of Para, Danaea trifoliata Kunze and Lindsaea divaricata Klotzsch, and two, for the North Region of Brazil: Cyclodium heterodon (Schrad.) T. Moore var. abbreviatum (Presl) A.R. Sm. and Thelypteris chrysodioides (Fee) C.V. Morton.

Abstract: This paper provides keys, illustrations, short descriptions, and voucher specimen citations for the ferns and lycophytes of Acre, Brazil. We recognize a total of 212 species in 66 genera and 28 families. Of these, the lycophytes are represented by 14 species, 4 genera, and 2 families, and the ferns by 8 varieties, 1 subspecies, 198 species, 62 genera, and 26 families. The total represents an increase of 22 species and two varieties compared to a checklist published in 2009. The six most species-rich genera are Adiantum (21 spp.), Asplenium (14), Selaginella (12), Trichomanes (11), Lindsaea, and Microgramma (9 each). None of the species treated here are endemic to Acre. A new combination is made for Meniscium chrysodioides Fee var. goyazense.