Adriana Hissae Hayashi

Comparative leaf morphology and anatomy of three Asteraceae species

ABSTRACT The objective of this paper was to describe and compare the morphology and anatomy of mature leaves of Mikania glomerata Spreng., Porophyllum ruderale Cass. and Vernonia condensata Baker (Asteraceae) species that have different habits emphasizing their secretory structures. Longitudinal and transversal sections of mature leaf blades of the three species were analyzed at the apex, base, and medium third part of the midvein of the leaf blade and of the margin. M. glomerata had uniseriate glandular trichomes and secretory ducts; P. ruderale had hydathodes and secretory cavities; and V. condensata had idioblasts and uni- and biseriate glandular trichomes. Key words: Mikania glomerata, Porophyllum ruderale, Vernonia condensata, secretory structures, medicinal plants * Author for correspondence INTRODUCTION The Asteraceae family consists of approximately 25000 species (Barroso, 1986) included in over 1100 genera. These species frequently present herbaceous habits, although arboreous and voluble herbaceous habits also occur (Cronquist, 1981). Because of this variety of habits, the family presents various anatomical structures and in some cases ecological specialization may occur (Metcalfe and Chalk, 1950). Secretory structures are of great taxonomical interest and their restricted distribution has an important diagnosis value (Metcalfe and Chalk, 1950; Fahn, 1979). Frequently, in Asteraceae, they occupy distinct positions in different organs of the plant occurring in all, some or in only one organ (Solereder, 1908). Castro et al. (1997) reviewed the types of secretory structures in the leaves of seventy two representatives of the Asteraceae family from the cerrado vegetation in the Reserva Biologica de Mogi Guacu, Sao Paulo, Brazil. When analyzed together these secretory structures presented diagnosis value at genus level. Eight types of leaf secretory structures were mentioned: ducts, cavities, idioblasts, laticifers, hydathodes, extrafloral nectaries, trichomes and glandular appendixes. According to Metcalfe and Chalk (1950), anatomical diversity is commonly observed in the structure of leaves of species belonging to the Asteraceae. Among the features that vary are: (a) stomata distribution on leaf surfaces; (b) guard-cell positioning in relation to ordinary epidermal cells; (c) hypoderm development on the upper side of the leaf surface; (d) mesophyll and fibrovascular system differentiation; and (e) wax secretion on leaf surface (Solereder, 1908). The anatomical features that can be observed in Asteraceae are: (a) presence of various types of glandular or covering trichomes; (b) papillae on

The origin and anatomy of rhizophores in Vernonia herbacea and V.platensis (Asteraceae) from the Brazilian Cerrado

The aim of this work is to study the origin and anatomy of rhizophores in two Asteraceae species from the Brazilian Cerrado: Vernonia herbacea (Vell.) Rusby and V. platensis (Spreng.) Less. In both species, axillary buds from the cotyledonary node give rise to the first rhizophores. As rhizophores develop, these organs branch to form new rhizophores from their axillary buds that constitute a sympodial system of underground branches. Nodes, internodes and axillary buds, protected by cataphylls, are evident in these underground organs. The primary root degenerates and all the root system arises adventitiously from the rhizophores. Under natural conditions, the axillary buds give rise to new rhizophores, but when exposed to the light, these buds develop into aerial stems. When rhizophores are fragmented, each of these structures, which accumulate fructans, are important organs for vegetative propagation mainly in areas subjected to environmental disturbances, such as the Cerrado, where fire and drought frequently occur.

Underground systems of Asteraceae species from the Brazilian Cerrado1

Abstract Underground systems of Asteraceae species from the Brazilian Cerrado. The aim of this study was to describe the underground systems structure, the origin of the shoot buds, and to identify the storage reserve of seven Asteraceae species in order to understand the adaptive strategies of these species in burned Cerrado areas and their higher frequency in the floristic surveys for herbaceous and undershrub layers of this biome. The subterranean systems types—diffuse underground system, rhizophore, tuberous roots, and xylopodium—varied among the studied species, but all of them have high shoot bud-forming potential. Fructans of the inulin type were detected as storage substances. The presence of these characteristics on the underground systems could explain the frequency of these species in the floristic surveys from the Brazilian Cerrado, in which fire and seasonal drought are frequent. It is possible that the belowground bud banks in the Cerrado biome are as important as demonstrated in North American prairies where fire is also frequent. However, in the Cerrado, as demonstrated here, there are types of underground systems other than rhizomes that are usually described in the prairie. Understanding the anatomical features of these plants is one of the steps to appropriate conservation management of these species in the Cerrado.

Anatomy of the underground system in Vernonia grandiflora Less. and V. brevifolia Less. (Asteraceae)

This work dealt with the anatomy of the underground system in Vernonia grandiflora Less. and V. brevifolia Less. (Vernonieae; Asteraceae), two perennial geophytes, to elucidate their ability to sprout in the Brazilian Cerrado conditions. V. grandiflora , a subshrubby species, possessed a thickened under ground system constituted by a xylopodium and many tuberous roots. The xylopodium had stem and root structure and its buds were axill ary or originated from the cortical parenchyma proliferati on. The tuberous roots produced by this organ were adventitious and accumulated inulin-type fructans mainly in the cortical parenchyma. The thickened underground syst em of V. brevifolia , an herbaceous species, was a tuberous primary roo t whose buds originated from the proliferated pericycle. The occurrence of these bud-forming unde rground systems, which stored reserve compounds, en abled these plants to survive throughout unfavourable env ironmental conditions in the Cerrado, such as dry s eason and frequent fires in the winter.

Anatomy of vegetative organs in Aldama tenuifolia and A. kunthiana (Asteraceae: Heliantheae)

The South American species of the genus Viguiera (Asteraceae) have been transferred to Aldama based on molecular studies. However, the circumscription of Aldama tenuifolia and A. kunthiana has not been well established because the two species are morphologically similar. Both occur in areas of the Cerrado domain, especially in “campos sujos”, “campos limpos” and “campos rupestres”, which are characterised by intense solar irradiation, water scarcity during the autumn and winter, and frequent fires. The aim of the present study is to analyse the anatomy of the vegetative organs of both species in order to identify features that may be useful in their circumscription and in understanding their environmental adaptations. Samples of leaves, stems, xylopodia and roots of each species were collected, fixed, and processed according to the usual methods for light and scanning electron microscopy. The anatomical features useful to delimit the two species are the contours of the epidermal cell walls and in the occurrence of secretory ducts in the primary phloem and fundamental parenchyma of the midrib (leaves), the occurrence of secretory ducts in the primary and secondary phloem (stems) and the degree of cambial activity in the tuberisation process (roots). Regarding the environmental adaptation, both species share the presence of a xylopodium with a high bud shoot-forming potential, fructan accumulation in the tuberised roots, root-mycorrhizal associations, the occurrence of secretory structures, such as glandular trichomes (stems and leaves), internal secretory spaces (roots, xylopodia, stems and leaves) and hydathodes (leaves).

Morpho-anatomy and fructans in the underground system of Apopyros warmingii and Ichthyothere terminalis (Asteraceae) from the cerrado rupestre1

Abstract The cerrado rupestre is a physiognomy of the Cerrado biome with a prominent ground layer. It is characterized by rocky outcrops; acidic, nutrient-poor soil; and water shortage due to climatic seasonality. Species of this biome have several mechanisms to survive these adverse conditions. This study aimed to investigate morpho-anatomical characteristics and soluble carbohydrates in underground systems of Apopyros warmingii and Ichthyothere terminalis (Asteraceae), and to evaluate the potentially adaptive roles of these structures under the environmental stressors of the cerrado rupestre. Samples of underground organs were fixed, dehydrated in graded ethylic ethanol, embedded in historesin, and sectioned. Qualitative and quantitative analyses of soluble carbohydrates were performed in distinct portions of the underground systems. Thickened underground systems of both species are composed of stem and root portions with buds in the proximal region. Vascular and cortical parenchymas are abundant and accumulate inulin, which can be visualized as spherocrystals. Secretory structures have lipophilic secretion. High fructan amounts in the parenchyma indicate their use to support resprouting. These carbohydrates may be mobilized to meet the increased demands of phenology and abiotic factors. Secretory structures and sclereids in both species and raphides in A. warmingii may assist the protection of the underground system against herbivores.

Aspectos fisiológicos, anatômicos e ultra-estruturais do rizoma de Costus arabicus L. (Costaceae) sob condições de déficit hídrico

Costus arabicus L. is an herbaceous species, native to the forest that accumulates starch in the rhizome as the main reserve carbohydrate. Water stress is one the most important environmental factor that regulates plant growth and development, leading to changes in physiological, biochemical and anatomical traits. The aim of this study was to evaluate the effect of water deficit on the anatomy, carbohydrate concentration and ultrastructure of starch grains of the rhizome of Costus arabicus L. through the following water regimes: plants irrigated daily and every seven (7d) and 15 days (15d). Anatomical and ultrastructural traits of the rhizome, relative water content in leaves (RWC), leaf water potential (Ψw), osmotic potential of the rhizome (Ψo), total soluble sugars (TSS), reducing sugars (RS) and starch of the rhizome were evaluated. We observed significant reductions in Ψw and Ψs in 15d plants, but with small variations in the RWC. The anatomical analysis showed that the rhizome is covered by epidermis or stratified cork and there is a delimitation between the cortical and vascular regions. We detected the presence of numerous starch grains and idioblasts with phenolic contents in the parenchyma of the two regions. Changes in the anatomy of the rhizomes were only observed in plants irrigated every 15 days, in which cells of covering tissue and the outer cortical layers became more flattened and sinuous walls; however, no ultrastructural differences were observed on the starch grains. The water deficit imposed was sufficient to generate physiological, biochemical and anatomical changes in plants of C. arabicus L. Such alterations suggest the occurence of an avoidance mechanism and that anatomical changes were dependent of the intensity and duration of water deficit.

Anatomy and function of the root system of bromeliad Nidularium minutum

The root anatomy of bromeliad Nidularium minutum Mez was studied and the efficiency of root system in contributing to the growth, development and mineral uptake of the species evaluated. To accomplish this analysis, four treatments were applied as follows: (i) control plants with 5 mL H2O on substrate and 5 mL H2O into tank; (ii) plants supplied with nutrients to the tank with 5 mL H2O on substrate and 5 mL Hoagland and Arnon solution into tank; (iii) plants supplied with nutrients to the roots with 5 mL HA on substrate and 5 mL H2O into tank; and (iv) plants supplied with nutrients to the tank and roots with 5 mL HA on substrate and 5 mL HA into tank. Biometric variables and biomass were measured. Contents of macro- and micronutrients were evaluated in leaves, and the anatomical structure of roots was analysed. Structurally, the roots possess multiseriate epidermis, termed velamen, which is typical in Orchidaceae and other families for taking up water and nutrients. Plants supplied with nutrients to the roots had higher values than control plants for fresh and dry mass of stems, leaves and total (leaves + stems + roots), besides being more efficient than plants supplied with nutrients to the tank for nitrogen uptake. These results indicate that root system of N. minutum is very efficient for nutrients uptake when compared with the tank contributing to plant growth and development, most likely assisted by the presence of velamen.