Doryopteris triphylla (Pteridaceae-Cheilanthoideae) grows in xeric habitats in Brazil, Paraguay, Uruguay and Argentina. The aim of this study was to characterize D. triphylla anatomically, histochemically and cytogenetically. For anatomical characterization, rhizomes, roots, petioles and leaves were made and then stained using Safranine-Astra Blue for further observations. Leaf blades were also cleared. For histochemical analysis, leaf cross sections were stained with different reagents to identify glandular trichomes compounds. For cytogenetic characterization, a karyogram was performed using laboratory cultivated roots. Results show a dictyostelic rhizome covered with scales with apical secreting gland; diarch roots; petiole cross-sections show thick cuticle, uniseriate epidermis, parenchymatic cortex cells with thick walls and a vascular bundle with two xylem groups; and hypostomatic fronds with glandular trichomes. Histochemical studies of secretion products of the glandular trichomes were positive for polysaccharides, pectins, lipids, acid lipids, dihydroxyphenols, phenols and flavonoids. Cytogenetically, D. triphylla is described as a diploid species (2n = 60), with chromosomes gradually decreasing in size. The apical glands in scales of rhizomes, the presence of two xylem groups in the vascular bundle in the petiole and the glandular trichomes on the abaxial surface are new contributions to the species. The type of chemical products secreted by glandular leaf trichomes and karyotype estimation is shown for the first time in this species.
Argyrochosma nivea var. tenera is a cheilanthoid fern from the American continent. We present herewith the study of meiotic behavior and gametic number as well as number of spores and reproduction mode (with observations from cultured gametophytes). The study material is from Northwestern Argentina. For the study of meiosis, sporangia were fixed in ethanol-acetic acid (3:1) and stained with 2% propionic haematoxylin. Micrographs were taken using light and scanning electron microscopes. Meiotic chromosome number is 2n = 3x = 81 and the presence of lagging chromosomes at telophase II is mentioned for the first time; three sets of chromosome occur at diakinesis. Sporangia have 32 trilete spores. Adult gametophytes are laminar, cordiform, asymetrical, glabrous, without glandular trichomes. In our samples, the adult gametophytes were neuter, without antheridia or archegonia, with obligate apogamous reproduction. Both populations studied might be of hybrid origin.
Two new infraspecific taxa of Begonia micranthera Griseb. are described. Begonia micranthera subsp. albonervia Tebbitt is described and illustrated as a new subspecies native to the Andes of southern Bolivia (Chuquisaca, Cochabamba and Santa Cruz Departments). Begonia micranthera subsp. micranthera var. flava Andrada & Bulacio is newly described from Argentina's Jujuy Province. Begonia micranthera var. rhacophylla Irmsch. is raised to subspecies and newly recorded from Bolivia. Begonia micranthera var. hieronymi (Lindau) L.B.Sm. & B.G.Schub. is recognised as B. micranthera subsp. rhacophylla var. hieronymi (Lindau) L.B.Sm. & B.G.Schub. The type collection of Begonia micranthera var. foliosa L.B.Sm. & B.G.Schub. is newly recognised as a hybrid between B. micranthera Griseb. subsp. micranthera and B. micranthera subsp. rhacophylla (Irmsch.) Tebbitt. Begonia micranthera var. fimbriata L.B.Sm. & B.G.Schub. is newly synonymised with B. cinnabarina Hook. Begonia cinnabarina is newly recognised from Argentina and is lectotypified. Begonia micranthera subsp. micranthera var. nana L.B.Sm. & B.G.Schub. is also lectotypified. A key, diagnoses and illustrations are provided for all the recognised infraspecific taxa of Begonia micranthera.
Halerpestes (Ranunculaceae) es un género pequeño el cual contiene 13 especies. Tres de ellas son típicas de la región del Noroeste Argentino: H. cymbalaria, H. exilis y H. uniflora. En investigaciones recientes se separó a H. exilis como una especie diferente de H. cymbalaria, ya que era considerada una forma de esta última. En este trabajo se realizaron recuentos cromosómicos y cariotipos de H. cymbalaria y H. exilis mediante técnicas citogenéticas clásicas. Los resultados fueron concluyentes en que ambos taxones son diploides y presentan 2n = 16 cromosomas, cariotipos asimétricos y unimodales; sin embargo, existen diferencias en el tamaño cromosómico y la organización de la cromatina, teniendo H. exilis un par cromosómico con satélite no observado en el otro taxón. La ubicación de H. cymbalaria y H. exilis como especies diferentes, realizada por diferentes autores, es afianzada por nuestros resultados.
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