Nanuza Luiza de Menezes

Cytogenetics and cytotaxonomy ofVelloziaceae

Chromosome number and other cytological features are reported from 35 species ofVelloziaceae, including several African and Brazilian populations. All analyzed species show areticulate interphase nuclei and prophase/prometaphase chromosomes with proximal early condensation. Most heteropycnotic blocks do not seem to correspond to heterochromatin since, at least inVellozia patens, they do not stain differentially after C-banding procedures. Regarding the chromosome number, three main groups could be identified. The first comprised diploid species of the generaNanuza, Vellozia and the Brazilian species ofXerophyta with 2n = 14 or 16; the second comprised tetraploid species with 2n = 34, and included all Brazilian species of subfam.Barbacenioideae; the third group, of hexaploid species, comprised the African representatives of the genusXerophyta. A single population ofVellozia, possibly of hybrid origin, had 2n ≅ 32. A basic number of x = 8 is proposed for the family. The karyological information supports the hypothesis that theVelloziaceae originated on the South American, rather than on the African continent.

Alkanes of foliar epicuticular waxes of velloziaceae

Abstract One hundred and ten species of Velloziaceae were surveyed for the distribution of the alkanes in their foliar epicuticular waxes. Longer chains were found in waxes of representatives of subfamily Barbacenioideae, the main homologues being mostly n -C 33 or n -C 35 except most members of Pleurostima , which had n -C 31 or n -C 33 the main alkane. In Vellozioideae, the main alkane was chiefly n -C 29 . The results support proposals for the establishment of Burlemarxia and the re-establishment of Pleurostima , but does not lend support to the recognition of Brazilian Xerophyta as distinct from Vellozia and of Aylthonia as distinct from Barbacenia . In some cases very small or no differences were noted among the alkane profiles of different specimens of the same species, but in other cases substantial differences were detected.

Meristematic endodermis and secretory structures in adventitious roots of Richterago Kuntze (Mutisieae-Asteraceae)

The meristematic endodermis in adventitious roots of Richterago species originates in one of the fundamental meristem cells, which undergo sucessive anticlinal and periclinal divisions to build the inner cortex. The meristematic endodermis or proendodermis remains as a meristematic layer until its differentiation into endodermis, with Casparian strip. When sieve elements differentiate, endodermic secretory canals of esquizogenous origin are present at the region adjacent to primary phloem. Articulated laticifers, with cells perforated at both terminal and transversal walls, also occur during initial phases of secondary development. Presence of inulin as reserve carbohydrate in the inner cortex and vascular tissue may be related to abiotic factors, as an adaptive strategy of these species.

Anatomia da raiz de espécies de Dyckia Schult. f. e Encholirium Mart. ex Schult. & Schult. f. (Bromeliaceae, Pitcairnioideae) da Serra do Cipó (Minas Gerais, Brasil), com especial referência ao velame

An anatomical study of roots in species of Dyckia and Encholirium demonstrates as principal feature the presence of several layered epidermis that forms a velamen. The epivelamen has root hairs. The hypodermis has thickened walled, non living cells and some non thickened walled and living passage cells. It is one or several layred in different levels and entirely lignified. Its also observed that the other zones of the cortex are more or less thickened, depending on the level (thicker when next to the stem). The roots examined were adventiceous, with a pith, except the tap root of the young plant.

Vegetative organ anatomy of Ianthopappus corymbosus Roque & Hind (Asteraceae-Mutisieae)

A study on the vegetative organ anatomy of Ianthopappus corymbosus was conducted in order to provide a basis for comparison with the genus Richterago, since this species had been previously included in that genus. The anatomical characters of I. corymbosus that support its exclusion from the genus Richteragon are: epithelial cell organization of adventitious root secretory canals, non-glandular trichomes, and presence of cortical vascular bundles in the stem. In Ianthopappus corymbosus, the underground system consists of rhizophore from which adventitious roots branch off. The subapical meristem of the adventitious root revealed that the ground meristem forms the inner layer which in a meristematic phase, forms 2/3 of the cortex. This layer will differentiate in the endodermis, with Casparian strips, and is referred to as meristematic endodermis. Endodermic secretory canals, limited by four epithelial cells, appear in the region adjacent to the primary phloem.

The redifferentiation of nutritive cells in galls induced by Lepidoptera on Tibouchina pulchra (Cham.) Cogn. reveals predefined patterns of plant development

Insect galls may present nutritive tissues with distinct cytological features related to the order of the gall inducer. Galling Lepidoptera larvae chew plant cells and induce the redifferentiation of parenchymatic cells into nutritive ones. The nutritive cells in the galls induced by a microlepidoptera on the leaves of Tibouchina pulchra (Cham.) Cogn. (Melastomataceae) are organelle-rich, with developed Golgi apparatus, endoplasmic reticulum, ribosomes, polyribosomes, mitochondria, plastids, and one great central or several fragmented vacuoles. The nonobservance of the nuclei in the nutritive cells deserves special attention, and confers a similarity between the nutritive cells and the vascular conductive ones. The great amount of rough endoplasmic reticulum, ribosomes, polyribosomes, and mitochondria is indicative of the high metabolic status of these cells. They are vascular cambium-like, with high protein synthesis and lipid storage. The proteins are essential to enzymatic metabolism, and secondarily, to larvae nutrition, similarly to the lipid droplets which confer energetic profile to these nutritive cells. The living enucleated cells receive mRNA from their neighbor ones, which may support the high metabolic profile of endoplasmic reticulum and ribosomes observed in galls. Thus, the nutritive cells are stimulated by the galling larvae activity, generating a new cell type, whose redifferentiation includes a mix of intrinsic and common plant pathways.

Morfoanatomia do sistema subterrâneo de Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson (Asteraceae)

Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson (Asteraceae), known as yacon is a high-altitude tropical herbaceous species. It was introduced into several countries, including Brazil, because of its nutritional potential, high yield but mainly as a source of inulin. Although its agronomy and biochemistry are relatively well established, little is known about the morphology and nature of its underground system, the main inulin source. The underground system is heterogeneous in nature, consisting of rhizophores, and adventitious thin and tuberous roots. The rhizophores and roots present secretory ducts of lipid in the inner cortical layers, which is derived from the meristematic endoderm.

Aspectos da anatomia foliar de algumas espécies de Paepalanthus Kunth, Eriocaulaceae da Serra do Cipó - Minas Gerais

O estudo da anatomia foliar das especies de Paepalanthus Kunth.: P. bromelioides Silv.; P. macropodus Ruhl.; P. microphyllus (Giull.) Kunth; P. paulinus Ruhl.; P. robustus Silv.; P. scleranthus Ruhl. e P. speciosus (Bong.) Koer. mostrou uma semelhanca no numero e distribuicao dos feixes vasculares, Em P. robustus e, menos marcadamente, em P. speciosus, estes feixes de tamanhos diferentes, encontram-se distribuidos em series, com os feixes menores mais proximos da epiderme adaxial. As folhas revelam caracteristicas xerofiticas em diferentes graus. Chama-se a atencao para a formacao de feixes vasculares anfivasais no apice das folhas.

Primary and secondary thickening in the stem of Cordyline fruticosa (Agavaceae)

The growth in thickness of monocotyledon stems can be either primary, or primary and secondary. Most of the authors consider this thickening as a result of the PTM (Primary Thickening Meristem) and the STM (Secondary Thickening Meristem) activity. There are differences in the interpretation of which meristem would be responsible for primary thickening. In Cordyline fruticosa the procambium forms two types of vascular bundles: collateral leaf traces (with proto and metaxylem and proto and metaphloem), and concentric cauline bundles (with metaxylem and metaphloem). The procambium also forms the pericycle, the outermost layer of the vascular cylinder consisting of smaller and less intensely colored cells that are divided irregularly to form new vascular bundles. The pericycle continues the procambial activity, but only produces concentric cauline bundles. It was possible to conclude that the pericycle is responsible for the primary thickening of this species. Further away from the apex, the pericyclic cells undergo periclinal divisions and produce a meristematic layer: the secondary thickening meristem. The analysis of serial sections shows that the pericycle and STM are continuous in this species, and it is clear that the STM originates in the pericycle.The endodermis is acknowledged only as the innermost layer of the cortex.

Anatomia do escapo e rizoma de espécies brasileiras de Bulbostylis Kunth (Cyperaceae)

Bulbostylis Kunth (subfamily Cyperoideae) comprises approximately 150 species with centers of distribution in South America and Africa. The anatomy of the scapes was studied in 40 species of Bulbostylis. The characters found to be of taxonomic value in the key species are: the shape of the scape in transverse section, the presence of ribs and furrows, the aspect of the epidermal cells and stomata, the shape of the cortical sclerenchymatous strands, the number of vascular unit, a fistulose medulla, and the occurrence of radiate parenchyma. These characters were found to be diagnostically useful at the specific level. We also show that the scape should be considered a monostele. The atactostele appears in the rhizome.