Anatomical studies of the secretory structures: Glandular trichomes and ducts, in Grindelia pulchella Dunal (Astereae, Asteraceae)

The ultrastructure of the glandular trichomes and secretory ducts of Grindelia pulchella was studied. Plastids, mitochondria and endoplasmic reticulum are involved in the secretory process of both, trichomes and ducts. A special tissue with “transfer cells” is associated with the duct epithelial cells. The secretion is produced in the transfer cells and then is transferred to the duct epithelial cells where it accumulates in the vacuoles. The occurrence of cavities within the cell walls of the trichome cells and duct epithelial cells is described. The secretion is accumulated between the cell wall and the cuticle of these cells. When the cuticle is broken the secretion is released. We conclude that granulocrine secretion operates in this species.     

Anatomical evidence and the taxonomic position of Darmera (Saxifragaceae)

GORNALL, R. J., 1989. Anatomical evidence and the taxonomic position of Darmera (Saxifragaceae). Evidence from the anatomy of nodes, petioles, trichomes, leaf crystals, ovules and seed-surfaces agrees with other published data to show that segregation of Darmera from the Saxifragaceae is unwarranted. The combined evidence indicates that the closest relatives of the genus are Astilboides, Bergenia and Mukdenia. A putative hybrid origin for this group of genera is suggested.     

Structures and functions of adventitious roots in species of the genus Philodendron Schott (Araceae)

We discuss here the anatomical variations of the arrangements and compositions of stele types observed in different roots types in four populations of the three species of Philodendron as probable adaptations to their habitats. Terrestrial individuals of P. corcovadense have cylindrical steles while rupicolous individuals have lobate steles with dispersed internal cortical parenchyma. The Philodendron species sampled showed polyarch structures. The crampon roots of P. oblongum and anchor roots of P. cordatum show medullated protosteles, with the former species having a reduced pith with sclerified parenchyma cells while the latter has a wide pith and parenchyma cells with only slightly thickened walls. The feeder roots of P. cordatum also show a medullated protostele—although a central vessel is present until approximately 60 cm from the apex that later disappears, forming a parenchymatous pith. We conclude that the different root types reflect adaptations of the subgenera Philodendron and Meconostigma to their different habits and habitats, such as in P. corcovadense, where the roots of rupicolous individuals have lobate steles while the roots of the terrestrial plants have cylindrical steles.     

Pothos crassipedunculatus,a new species ofPothos sect.Allopothos (Araceae) from India

Pothos crassipedunculatus Sivadasan & Mohanan (Araceae), a new species closely related to the SW. Indian endemic and little known speciesP. thomsonianus Schott is described. It is characterized by the the non-ligulate, shortly vaginate petiole, thickly peduncled inflorescence, broadly ovate spathe and a sessile spadix. It is included in ser.Brevivaginati Engler of sect.Allopothos Schott.     

Fruit anatomy of species of Solanum sect. Acanthophora (Solanaceae)

The fruits of 10 species of Solanum sect. Acanthophora were studied. Cross and/or longitudinal and/or tangential microtome sections, stained mostly with astra blue/basic fuchsin, were made for microscopic examination. Three different kinds of cells were found in the epidermis, immediately below which a hypodermis, consisting in any of four types of structures, was always found. The mesocarp exhibits two histologically differentiated zones, an external one (formed by normal or spongy parenchyma, according to the species), and an internal one, commonly juicy, and with proliferations among the seeds. The diagnostic value of all these structures is assessed. Morpho-anatomical information is used to define fruit types beyond the berry, traditionally described for Solanum, and the probable dispersal syndrome related to them is discussed. Fruit similarities are slightly noticeable in several cases, while differences may be the result of their sexual system – which affects specially the size – and their histology, which is related to the dispersal syndrome. The comparison of our data with previous molecular phylogeny of the section suggests that a significant morphological variation is not associated with significant DNA sequence changes.     

Anatomy of the extrafloral nectaries in species of Chamaecrista section Absus subsection Baseophyllum (Leguminosae,Caesalpinioideae)

In this paper the ontogenesis and histochemistry of the petiolar glands found on the petiole/rachis of the eight Chamaecrista species of the section Absus, subsection Baseophyllum (Leguminosae, Caesalpinioideae) are studied by using light microscopy techniques, aiming to characterise these structures and to provide taxonomic characters which may be useful in phylogenetic approaches. Strips for glucose identification reacted positively with the exudates of the glands, confirming the presence of nectar in the secretion, characterising these glands as extrafloral nectaries (EFN). Histochemical tests also detected the presence of neutral and acid muco-polysaccharides, pectins, mucilages, total proteins, and phenolic compounds in the EFNs. The EFNs arise from a group of meristem cells (protodermis, ground meristem and procambium) in the petiole/rachis. All EFNs of the investigated taxa share some morpho-anatomical characters, so that their peculiarities are too weak to be used alone in the identification of particular species. Rather their similarities may be used to include these species into a single group, supporting the hypothesis of monophyly of the subsection Baseophyllum.     

Characterisation of the effects of leaf galls of Clusiamyia nitida (Cecidomyiidae) on Clusia lanceolata Cambess. (Clusiaceae): Anatomical aspects and chemical analysis of essential oil

Galls develop in different plant organs and are induced by the activity of various organisms. Some studies have investigated the ecological interactions between species of Clusia and gall-inducing insects. The goal of our study is to characterise changes in leaf anatomy caused by the activity of gall insects in Clusia lanceolata. Additionally, we also investigated the chemical composition of volatile compounds of normal leaves and those with galls to detect possible effects on the host plants. For anatomical studies, we used botanical material fixed in FAA₅₀. Transversal sections of the leaf blade were obtained from samples of leaves located on the third and fourth nodes from both male and female individuals. Material was studied from both sexes both with unaffected leaves and leaves containing galls. Fresh leaves of C. lanceolata were used for the extraction of volatile compounds, which were submitted to stem distillation using a modified Clevenger apparatus determining the oil yields subsequently (w/w). The unaffected leaves of female and male individuals of C. lanceolata exhibit similar anatomical structures. However, galls on leaves of both sexes show anatomical differences. The activity of the gall insect Clusiamyia nitida induces several changes in the foliar anatomy and the distribution of metabolic compounds in new tissues during gall development. However, the larvae are not able to induce significant changes in the volatile compounds of inflected leaves from male and female individuals.     

Novel reports of glands in Neotropical species of Indigofera L. (Leguminosae,Papilionoideae)

By considering controversial discussions in the literature with regard to gland denomination in Indigofera species, as well as the taxonomic value of secretory structures in Leguminosae, we aim to morphologically detail glands that had been previously observed in I. microcarpa and I. sabulicola, and to investigate the occurrence of glands in vegetative and reproductive organs of other six Neotropical species that belong to the genus. Glands analyzed through scanning electronic microscopy (SEM) in combination with anatomic analyses correspond to secretory trichomes that are classified into seven types. Main variations in relation to types occurred with regard to head shape and peduncle size. Trichome heads were multicellular, with a thin cuticle. Hollow heads with conspicuous inner space characterized only one type (type 1); the other trichome types had massive heads. Peduncles, which varied from biseriate to multiseriate, had thick, pecto-cellulosic cell walls. Trichomes were found on stems, stipules, petioles, rachis, petiolules, leaflets, bracteoles, sepals, standards and fruits, more commonly along the margins. Each of the eight Indigofera species analyzed had at least two different trichome types out of the seven types that occurred in reproductive and vegetative organs of these taxa. Various types of secretory trichomes were found in I. campestris, I. lespedezioides, I. microcarpa, I. spicata, I. suffruticosa and I. truxillensis. Stems and rachis were the vegetative organs in which a greater variety of trichomes occurred, and sepals were parts of reproductive organs with the same status. Five out of the seven secretory trichome types occurred on both vegetative and reproductive organs. Distribution and gland types differed between species and these gland distribution patterns can be used as diagnostic characters. Reports of glands in Indigofera campestris, I. hirsuta, I. lepedezioides, I. suffruticosa, I. spicata and I. truxillensis, their recognition as secretory trichomes, and the morphological variety of types found for such trichomes are novel data for Indigofera.     

Colleters in Bathysa cuspidata (Rubiaceae): Development,ultrastructure and chemical composition of the secretion

This paper describes the development of colleters of Bathysa cuspidata, Rubiaceae, considering anatomical, histochemical and ultrastructural aspects and going from first differentiation stages until senescence. Further, the chemical composition of the secretion is investigated. The samples were prepared according to the usual techniques for light microscopy and scanning and transmission electron microscopy. Electrophoresis and thin layer chromatography (TLC) were used to confirm the results obtained in the histochemical tests. The colleters occur at the ventral surface of the stipules which protect the leaf primordia as well as the shoot meristem. The origin of the colleters is mixed, involving protoderm and ground meristem. The Bathysa colleters are of the standard type or are bifurcated; this latter type is documented here for the first time for Rubiaceae. Colleter secretion is a mucilage rich in protein, as determined by histochemical tests and confirmed by chemical analysis. Phenolic compounds and terpenes were detected only in the colleters themselves, but not in the secretion. The epithelial cells present conspicuous nuclei and nucleoli and the cytoplasm is rich in dictyosomes, endoplasmic reticulum, mitochondria, vesicles and small vacuoles with a fibrillar content. The accumulation of phenolic compounds and terpenes, the formation of a large central vacuole, the increase of the intercellular and subcuticular spaces occupied by the secretion and, finally, the darkening and the wilting of the colleters characterize the senescence of these structures. The secretion process of the colleters of B. cuspidata suggests a process of programmed cell death.     

Cortinarius sect. Brunnei (Basidiomycota, Agaricales) in North Europe

The section Brunnei was extensively studied based on material from North Europe. To stabilise the nomenclature we studied the relevant types of taxa included in this section. Phylogenetic relationships and species limits were investigated using rDNA ITS sequences and the results were compared with the morphological data. We recognised 11 species: Cortinarius brunneus, C. clarobrunneus comb. nov., C. coleoptera, C. ectypus, C. gentilis, C. glandicolor (neotypified), C. pseudorubricosus, and four species described as new C. caesiobrunneus, C. albogaudis, C. carabus, and C. cicindela. They are described here and their taxonomy, ecology, distribution, and relationships are discussed. In addition, a key to species of the section Brunnei is provided. A total of 77 new sequences of 11 species are published including nine type sequences. Also the taxonomic assignments of sequences in the public databases belonging to the section Brunnei are revised.     

Floral-like destiny induced by a galling Cecidomyiidae on the axillary buds of Marcetia taxifolia (Melastomataceae)

The galls induced by Cecidomyiidae, Diptera, are very diverse, with conspicuous evidence of tissue manipulation by the galling herbivores. Bud galls, as those induced by an unidentified Cecidomyiidae species on Marcetia taxifolia, Melastomataceae, can be considered as one of the most complex type of prosoplasma galls. The gall-inducer manipulate the axillary meristem of the plant in a way that gall morphogenesis may present both vegetative and reproductive features of the host plant. Herein, we analyzed traces of determinate and indeterminate growth in the bud gall of M. taxifolia, looking for parallels between the features of the leaves and flowers, natural fates of the meristematic cells. The bud galls are induced by the cecidomyiid fly, and are formed by the connation of eight leaf primordia, a common process in ovary morphogenesis. The bud gall corresponds to a pistil-shaped gall morphotype, with anatomical features similar to those of an hypanthium and sepals. The gall mimics an ovary, which has protective barriers at the apex, and a nutritive tissue (with storage of lipids and proteins) or a placenta, respectively, at the basal portion. The redifferentiation of the promeristem into a nutritive tissue at the base of the gall confers a determinate destiny to the axillary bud. Comparatively, the gradients of cell expansion and of accumulation of primary metabolites also indicate that the gall and the ovary are convergent structures. Some constraints of the host plant cells, such as the absence of lignification, and the accumulation of polyphenols, lipids and terpenoids, are not altered and may confer chemical protection for plant tissues and the larva against oxidative stress.     

Gagea tisoniana, a new species of Gagea Salisb. sect. Gagea (Liliaceae) from central Italy

Gagea tisoniana Peruzzi et al. sp. nov. is described and its taxonomic relationship is discussed. The new species, which appears to be endemic to central Italy, is close to G. pratensis (Pers.) Dumort., G. pusilla (F. W. Schmidt) Sweet, and other mainly poorly known [i.e. G. succedanea Griseb. et Schenk, G. transversalis Stev., and G. paczoskii (Zapal.) Grossh.] or as yet undescribed taxa from eastern Europe and the eastern Mediterranean area. The recognition of the new taxon G. tisoniana is claimed on the basis of anatomical, karyological, ecological, and phytogeographical data. Maps of the Italian distribution of G. pratensis (2 n  = 60), G. pusilla (2 n  = 24), and G. tisoniana (2 n  = 24) are presented, together with an analytical identification key. Finally, G. pratensis is recorded here for the first time in Tuscany (Monte Cetona).  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 337–347.     

Anatomical development of the pericarp and seed of Oncidium flexuosum Sims (ORCHIDACEAE)

Interpretation of the anatomical structure of the ovary and fruit of the Orchidaceae family is still controversial, which makes it difficult to understand the development and dehiscence of the fruit. The genus Oncidium is polyphyletic and is currently the subject of taxonomic studies. In this study, we have investigated the anatomical development of the pericarp and seed of Oncidium flexuosum Sims to determine important diagnostic characters that, along with molecular data, can assist in defining this group. We have found a new anatomical characteristic of the family: the presence of precursor cells for fruit dehiscence, which were visible from the beginning of development and located on the outer walls of the sterile valves. In contrast with what has been observed by different authors with other species, in the mature fruit of O. flexuosum, only the endocarp of the fertile valves and a few cells near the exocarp and the vascular bundle in the sterile valves show parietal thickening, while the rest remains parenchymatous. During the development of the ovule and embryo, we have shown that the embryonic sac of this species has eight nuclei and that the embryo has a long and elaborate suspensor.     

Distribution, structural and ecological aspects of the unusual leaf nectaries of Calolisianthus species (Gentianaceae)

Nectaries in leaves of Gentianaceae have been poorly studied. The present study aims to describe the distribution, anatomy, and ecological aspects of extrafloral nectaries (EFNs) of three Calolisianthus species and in particular the ultrastructure of EFNs in Calolisianthus speciosus during leaf development, discussing its unusual structure. Leaves of Calolisianthus species were fixed and processed by the usual methods for studies using light, scanning microscopy and transmission electron microscopy (TEM). Ion chromatography was used to analyze the nectar exudates of C. speciosus. The distribution patterns of nectar secretion units were analysed by ANOVA and t-tests. Two EFNs that can be seen macroscopically were observed at the bases of C. speciosus and C. pendulus leaves. Such large nectaries are absent there in C. amplissimus. Another similarly large EFN is observed at the apex of each leaf in all species. The EFNs at the base of the young leaves in C. speciosus are visited by ants during the rainy season. EFNs are formed by several nectar secretory units (nectarioles) that are present throughout the leaves. Each nectariole is formed by rosette cells with a central channel from which the nectar is released. Channels of old C. speciosus and C. pendulus EFNs were obstructed by fungi. TEM of EFNs in young leaves showed cytoplasms with secretion, small vacuoles, mitochondria, cell wall ingrowth, and plasmodesmata. TEM of EFNs in old leaves demonstrated dictyosomes, plastids, mitochondria, segments of endoplasmatic reticulum, and lipid droplets. The nectar contains sucrose, glucose and fructose.     

Development and morphology of the gynoecium and nutlet in two South-American Bulbostylis (Cyperaceae) species

The anatomy and ontogeny of the gynoecium and nutlets of two Bulbostylis species with different micro-morphology, Bulbostylis capillaris sensu Barros and B. major, were analyzed. The specific aim of this work was to identify which part of the pericarp determines the differences in the nutlet surface between these two species. We found that pre-fertilization development is the same in both species, with differences between species appearing only after fertilization. In the nutlet of B. major, the exocarp forms a tuberculate primary sculpture that has nipple-like protuberances consisting of one conoidal silica body per cell, whereas the secondary sculpture is micro-granulose and is constituted by the cuticle. In the nutlet of B. capillaris, the primary sculpture is granulose and is formed by the presence of starch granules in the exocarp that do not degrade, whereas the secondary sculpture is smooth.     

Leaf structure and histochemistry of Ecballium elaterium (L.) A. Rich. (squirting cucumber)

Light, scanning and transmission electron microscopy as well as histochemical reactions were employed to study the leaf structure and secretory activity of Ecballium elaterium, a hairy pharmaceutical perennial common in the Mediterranean region. The amphistomatic leaf has a peculiar structure due to special cells supporting the conductive bundles, a remarkable shortage of mechanical tissue, and the existence of pectin strands between mesophyll cells. The secreting activity is limited mostly to secretary hairs. These attributes of the Ecballium leaf fine structures do not resemble the common structure of leaves from Mediterranean plants and point to a peculiar strategy of this species coping with stress conditions of its habitat.     

地黄叶和茎的解剖学及组织化学研究

采用解剖学和组织化学方法对地黄叶和茎的显微结构以及梓醇、多糖的分布进行观察研究,以明确梓醇和多糖在地黄叶和茎中的分布特征。结果显示:(1)地黄叶的上、下表皮均分布有腺毛和非腺毛,腺毛都属于头状腺毛,包括长柄和短柄的头状腺毛,两类腺毛的分泌物化学成分主要是黄酮和多糖;叶的上、下表皮上都分布有无规则型气孔,下表皮的气孔密度比上表皮的大,但气孔指数相差不大;栅栏组织由2～3层薄壁细胞构成,排列紧密,海绵组织薄壁细胞形状无规则,细胞间隙大。(2)组织化学研究表明,海绵组织中黄斑样的薄壁细胞是梓醇和多糖的贮存场所,这类薄壁细胞在叶片边缘的齿末端处最为集中,茎的皮层、韧皮部和木质部的薄壁细胞也都是梓醇和多糖的贮存场所。     

Anatomy and histochemistry of the nectaries of Rodriguezia venusta (Lindl.) Rchb. f. (Orchidaceae)

Orchidaceae is one of the largest angiosperm families. Although extensively studied, reports of anatomy of secretory structures of orchids are relatively scarce. Rodriguezia venusta is an epiphytic orchid occurring in Brazil and Peru that has floral and extrafloral nectaries. This study describes the structure and the histochemistry of these secretory structures. Floral and extrafloral nectary samples were obtained from R. venusta plants that were collected in a gallery forest in the State of Bahia, Brazil, and grown in a greenhouse. Theses samples were fixed and processed according to routine procedures in plant anatomy and histochemistry or for scanning electron microscopy. The extrafloral nectaries occur on the edge and sub-edge of young leaves and at the basal portion of bracts that subtend the floral buds. They are structurally very similar, being formed by a nectary parenchyma and a simple epidermis with stomata (“non-structured nectaries”). The floral nectary is inserted at the floral receptacle fused with the labellum base, between this structure and the two inferior connate sepals. This nectary consists of an epidermis with numerous specific nectar secreting trichomes, a subnectary and a nectary parenchyma abundantly supplied by vascular terminations. Its structure is complex and distinct from other floral nectaries described for Orchidaceae.     

Histopathology of Aerococcus viridans var. homari infection (Gaffkemia) in the lobster, Homarus americanus, and a comparison with histological reactions to a gram-negative species, Pseudomonas perolens

Histological response of lobsters to injection of Aerococcus viridans var. homari, cause of gaffkemia, was followed over a 14-day period. Salient features in infected lobsters, Homarus americanus, were: aggregations of hemocytes occurring in hemal spaces throughout the tissues and increasing in number and size with time; the early phagocytosis of bacteria by the system of fixed phagocytes (FPs) present in hemal spaces of the hepatopancreas; and premature release of differentiating hemocytes from the hemopoietic tissue, so that by 14 days that tissue consisted mainly of large stem cells. Mass release of differentiating hemocytes presumably occurred to replace hemocytes lost from the circulation by their incorporation into aggregations or by lysis of individual cells ruptured through the pressure of phagocytized bacteria that were multiplying in them. Bacteria and their remains were present in FPs at 2 days but not visible in single or aggregated hemocytes until 6 days, when free bacteria were also present in the hemolymph. By 6 days, all bacteria, whether phagocytized or free, appeared normal and were surrounded by nonstaining halos that extended well beyond the stainable capsular material. As predicted earlier in physiological studies, gaffkemia is a nontoxic, noninvasive bacteremia. There was hemal stasis and consequent injury in the antennal gland due to free and aggregated hemocytes that occluded hemal spaces of that organ, but other tissues and organs appeared normal except for depletion of glycogen. Aggregations of hemocytes were present in lobsters 2 and 12 days after injection of a nonpathogenic, Gram-negative bacterium, Pseudomonas perolens. Unlike the case with gaffkemia, necrotic hemocytes were common in the aggregations, presumably in response to damage by endotoxin. A further difference was that aggregations were common in the heart of P. perolens-injected lobsters but rare in the heart of gaffkemic lobsters. Bacteria were not seen in hemolymph, hemocytes, or other cells of P. perolens-injected lobsters.