Automatic Leaf Epidermis Assessment Using Fourier Descriptors in Texture Images.

The identification of plant species is not a trivial task, since it is carried out by experts and depends on the presence of fruits, flowers and leaves. However, fruits and flowers are not available throughout the year, while leaves are accessible most of the year. In order to assist the specialized work of species identification, methods of texture image analysis are used to extract characteristics from samples of imaged leaves and thus predict the species. Texture image analysis is a versatile and powerful technique able to extract measurements from patterns in the images. Using this technique, recent research has found a close relationship between texture and plant species (da Silva et al., 2015 and 2016). Here, we describe the procedure to extract texture features from microscopic images of leaves using Fourier (Cosgriff, 1960; Azencott, 1997; Gonzalez and Woods, 2006). It is important to highlight that other methods for texture extraction can be used as well. This protocol is split into two parts: (A) leaf epidermal dissociation and (B) automatic method for leaf epidermal image analysis.

Leaf epidermis images for robust identification of plants.

This paper proposes a methodology for plant analysis and identification based on extracting texture features from microscopic images of leaf epidermis. All the experiments were carried out using 32 plant species with 309 epidermal samples captured by an optical microscope coupled to a digital camera. The results of the computational methods using texture features were compared to the conventional approach, where quantitative measurements of stomatal traits (density, length and width) were manually obtained. Epidermis image classification using texture has achieved a success rate of over 96%, while success rate was around 60% for quantitative measurements taken manually. Furthermore, we verified the robustness of our method accounting for natural phenotypic plasticity of stomata, analysing samples from the same species grown in different environments. Texture methods were robust even when considering phenotypic plasticity of stomatal traits with a decrease of 20% in the success rate, as quantitative measurements proved to be fully sensitive with a decrease of 77%. Results from the comparison between the computational approach and the conventional quantitative measurements lead us to discover how computational systems are advantageous and promising in terms of solving problems related to Botany, such as species identification.

Plant Identification Based on Leaf Midrib Cross-Section Images Using Fractal Descriptors.

The correct identification of plants is a common necessity not only to researchers but also to the lay public. Recently, computational methods have been employed to facilitate this task, however, there are few studies front of the wide diversity of plants occurring in the world. This study proposes to analyse images obtained from cross-sections of leaf midrib using fractal descriptors. These descriptors are obtained from the fractal dimension of the object computed at a range of scales. In this way, they provide rich information regarding the spatial distribution of the analysed structure and, as a consequence, they measure the multiscale morphology of the object of interest. In Biology, such morphology is of great importance because it is related to evolutionary aspects and is successfully employed to characterize and discriminate among different biological structures. Here, the fractal descriptors are used to identify the species of plants based on the image of their leaves. A large number of samples are examined, being 606 leaf samples of 50 species from Brazilian flora. The results are compared to other imaging methods in the literature and demonstrate that fractal descriptors are precise and reliable in the taxonomic process of plant species identification.

Pimenta pseudocaryophyllus (Gomes) L.R. Landrum (Myrtaceae): stem and leaf anatomy of a medicinal plant

O estudo de plantas medicinais envolve várias áreas da ciência. Neste contexto, a anatomia contribui para a identificação da espécie e consequentemente, com a qualidade do produto da planta. Este trabalho descreve a anatomia do caule e da folha de Pimenta pseudocaryophyllus (Gomes) L.R. Landrum (Myrtaceae), coletada em Floresta Estacional Semidecidual. Os órgãos estudados apresentaram epiderme unisseriada, recoberta com cutícula espessa, e cavidades secretoras. O caule apresentou anel contínuo de tecido vascular ao redor da medula, com o floema em ambos os lados do xilema. A folha foi hipoestomática com tricomas na face abaxial, com mesofilo bifacial e feixe vascular anficrival circundado por periciclo esclerenquimático no pecíolo e na nervura principal. Entre os testes histoquímicos, resultados positivos foram obtidos para lipídeos, compostos fenólicos, amido e oxalato de cálcio (drusas). A espécie apresentou aspectos anatômicos típicos da família e as cavidades secretoras presentes nas folhas foram relacionadas aos compostos secundários detectados.

The study of medicinal plants involves several areas of science. Anatomy contributes to species identification and consequently, with quality control of plant product. This paper describes the leaf and stem anatomy of Pimenta pseudocaryophyllus (Gomes) L.R. Landrum (Myrtaceae), collected in Seasonal Semideciduous Forest. The studied organs presented uniseriate epidermis covered by a thick cuticle and secretory cavities. The stem showed a continuous ring of vascular tissues around the pith, with phloem on both sides of the xylem. The leaf was hypostomatic, with trichomes on the abaxial face, with bifacial mesophyll and amphicrival vascular bundle, surrounded by a sclerenchymatous pericycle in the petiole and in the midrib. Among the histochemical tests, positive results were obtained for lipids, phenolic compounds, starch and calcium oxalate (druses). The species had anatomical features typical of the family and the secretory cavities present in leaves and stems were related to the secondary metabolites detected.

Morpho-anatomical alterations in plants of Lithraea molleoides (Vell.) Engl. submitted to flooding / Alterações morfoanatômicas em plantas de Lithraea molleoides (Vell.) Engl. submetidas ao alagamento - DOI: 10.4025/actascibiolsci.v29i1.408

Flooding effects in Lithraea molleoides plants were studied. Young plants were kept under drained and flooded soil over a period of 35 days. For growth and development analyses, the length and diameter of stem and main root and the dry weight of roots, stem, and leaves were measured. For anatomical studies, sections of fresh and fixed roots, stem bases and leaves were made using standard procedures in vegetal anatomy. The stress reduced the dry weight increment of plants without causing the death of roots or the abscission of leaves. In the stem base, flooding induced the hypertrophy of lenticels and the increase of intercellular space and reduction lower starch contents, in the cortex. Plants flooded displayed greater percentage of cortical intercellular space in the secondary roots and lower investment in secretory structure formation in the stem base. It can be suggested that flooding reduced the recourses allocation to growth. These recourses could be used in morphological alterations, such as hypertrophied lenticels and increase of intercellular spaces, that could contribute to plants survival during stress period, probably, due maintenance of aerobic respiration.

Visando contribuir para o conhecimento das estratégias de tolerância de espécies arbóreas à hipoxia, os efeitos do alagamento em plantas de Lithraea molleoides foram estudados. Indivíduos jovens foram mantidos em condições de solo drenado e alagado por 35 dias. Para as análises de crescimento e desenvolvimento, o comprimento e diâmetro do caule e raiz principal e o peso seco de raízes, caule e folhas foram medidos. Para os estudos anatômicos, foram realizados cortes de material fresco e fixado, de acordo com técnicas usuais em anatomia vegetal. As plantas alagadas apresentaram menor massa seca sem, contudo, ocorrer morte de raízes ou abscisão de folhas. Observou-se maior volume de espaços intercelulares nas raízes secundárias e na base dos caules dessas plantas, sendo que a última região apresentou lenticelas hipertrofiadas. As plantas alagadas apresentaram menor teor de amido na base do caule e menor investimento em estruturas secretoras. Sugere-se que o alagamento provocou redução na alocação de recursos para crescimento, os quais foram utilizados na produção de alterações morfológicas, como lenticelas hipertrofiadas e aumento dos espaços intercelulares. Essas alterações contribuíram para a sobrevivência das plantas durante o período de estresse, possivelmente por manter a respiração aeróbia

Parameters affecting the early seedling development of four neotropical trees under oxygen deprivation stress.

Some of the parameters that determine flooding resistance-and consequently habitat zonation-were investigated in four neotropical trees (Schizolobium parahyba, Sebastiania commersoniana, Erythrina speciosa and Sesbania virgata). The constitutive parameters of seeds (size, nature and amount of reserves) only partly influenced resistance to flooding, mainly through a high carbohydrate : size ratio. Parameters describing metabolic efficiency under stress conditions were more important. Among them, fermentation capacity and levels of ATP and of total adenylates played a key role. The highest resistance to anoxia was associated with increased availability of free sugars, elevated alcohol dehydrogenase activity and corresponding mRNA levels, more efficient removal of ethanol and lactate, and higher adenylate levels. Finally, as a lethal consequence of energy shortage, free fatty acids were released on a massive scale in the flooding-sensitive species Schizolobium parahyba, whereas lipid hydrolysis did not occur in the most resistant species Sesbania virgata.