Methods for double staining plant materials using astra blue and basic fuchsin are described here. These methods can be applied to free hand and microtome sections embedded in paraffin, paraplast or historesin. Also, they can be used to study isolated epidermal peels and pollen preparations. Temporary, semipermanent and permanent preparations were studied. Astra blue stained polysaccharides of the cell wall such as cellulose and pectins. Basic fuchsin showed an affinity for lignified, suberized or cutinized walls. The easy preparation of the reagents, excellent color contrast of the histological preparations, and brief staining times of some methods makes them useful for both routine research and didactic purposes. Also, excellent color or black and white photomicrography can be obtained after the double staining described here.

This paper proposes a new interpretation for primary thickening in monocotyledons. The anatomy of the vegetative organs of the following species was examined: Cephalostemon riedelianus (Rapataceae), Cyperus papyrus (Cyperaceae), Lagenocarpus rigidus, L. junciformis (Cyperaceae), Echinodorus paniculatus (Alismataceae) and Zingiber officinale (Zingiberaceae). The endodermis with meristematic activity was observed in the root of all the species, in the stem of Cyperus, Cephalostemum and Lagenocarpus rigidus, and in the leaf trace of Cyperus and leaf of Echinodorus. Considering the continuity of tissues through the root, stem and leaf, the authors conclude that in the stem the pericycle remains active throughout the life of the plant as the generator of the vascular tissue. The "Primary Thickening Meristem" is in fact the pericycle plus the endodermis and its derivatives (or only the pericycle). Close to the stem apex, the assemblage of seems to be a unique meristem, giving rise to the inner cortex and vascular tissues.

Palavras chave: Eriocaulaceae; Paepalantilus; anatomia foliar; feixes anfivasais; bainha mestomática.ABSTRACT: (Aspects of leaf anatomy of some species of Paepalanthus Kunth, Eriocaulaceae from Serra do Cipó -Minas Gerais). The anatomical studies in species of Paepalantlzus Kunth: P. brome/ioides Silv.; P. macropodus Ruhl.; P. microph)'llus (Giull.) Kunth; P. pau/inus Ruhl. ; P. robustus Silv.; P. scleranthus Ruhl. and P. speciosus (Bong.) Koem., show similarity in the number and distribution of the vascular bundles. In P. robusfus and, to a lesser extent, in P. speciosus, theses bundles of differing sizes occur in series, the smaller ones being closer to the adaxial epidermis. The leaves exhibit varying degrees of xeromorphy. Attention is drawn to the development of anphyvasal vascular bundles in the leaf apices.

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