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Although the petiole glands in Chamaecrista are usually termed extrafloral nectaries (EFNs), additional studies on the morphoanatomy and chemical nature of the exudates are necessary to properly classify a plant secretory structure. The correct classification of such structures is also important in taxonomic and phylogenetic studies. Based on standard anatomical procedures for light microscopy our study aims to broaden our current understanding of the EFNs in Chamaecrista. We describe and compare the ontogenesis and the morphoanatomy of the petiole EFNs in C. debilis and C. desvauxii var. langsdorfii, species that belong to two distinct sections in Chamaecrista. The morphoanatomy along with the presence of sugars in exudates supports the classification of the petiole glands in both species as EFNs. The EFN development is rapid, and their secretory activity starts before the young leaves complete their expansion. The major difference among the EFNs of both species is their outer morphology which is useful on the taxonomy. Both EFNs are anatomically similar and composed of a secretory epidermis, a nectariferous parenchyma and vascular tissue more abundant in phloem in comparison to xylem. [ABSTRACT FROM AUTHOR]

Leaf teeth are projections on the leaf blade margin. They are structurally variable, with characters that are important for taxonomy and phylogeny, but there is a paucity of information on the anatomy of these structures and little understanding of the features and their functions. Here we describe and compare the leaf tooth anatomy of 47 eudicot species. Toothed margin samples from leaves at different developmental stages were collected, fixed and studied under light and scanning electron microscopy. We identified eight leaf tooth morphotypes, six of which occurred with glands. Hydathodes were the most common glands, being found in 11 species; colleters were found in ten species and extrafloral nectaries were found in two species. Cunonioid teeth either devoid of glands or associated with hydathodes were found in Lamiales, Asterales and Apiales. Dillenioid teeth associated with hydathodes were found in Dilleniales. Spinose teeth associated with colleters were found in Aquifoliales. In rosids, we found begonioid, malvoid, theoid, urticoid and violoid teeth, which may be associated with either colleters or nectaries or lack an associated gland. For each family studied, there was only one type of association between gland and tooth, demonstrating the systematic potential of these glands in eudicots. [ABSTRACT FROM AUTHOR]

Colleters are secretory structures located in reproductive and (or) vegetative organs of many eudicots. In Gentianaceae Juss., the presence of foliar colleters has been neglected, and anatomical and histochemical studies are scarce. The objectives of this study were to investigate the anatomy, ontogeny, and chemical nature of the secretion found in Macrocarpaea obtusifolia (Griseb.) Gilg colleters to establish a relationship between their structure and function and check whether these structures are similar to those described for other genera of the Gentianaceae and other families of the Gentianales. Samples of leaves at different developmental stages were collected and processed for anatomical and histochemical analysis using light microscopy and scanning electron microscopy. Colleters in M. obtusifolia have a protodermal origin, are of standard type, and are not vascularized. Young colleters are translucent and produce an abundant amount of sticky secretion. Later, they turn yellowish with a blackened region at the apex of the head, and the secretion, composed of polysaccharides and proteins, becomes less abundant and brownish. During senescence, the process begins with complete degradation and cell collapse of the secretory portion. The colleters of the standard type in M. obtusifolia have been observed for the first time in the Gentianaceae and represent additional evidence that reinforces how common this type of colleter is in the Gentianales. Such results provide new information on the anatomy, ontogeny, histochemistry, and colleter types of Gentianaceae. [ABSTRACT FROM AUTHOR]

Schultesia Mart. comprises 21 closely related taxa. The revision of the genus showed that Schultesia pachyphylla Griseb. and Xestaea lisianthoides Griseb. are different from other species. The aim of this study was to describe the morphoanatomy of S. pachyphylla, comparing it with other Schultesia species and X. lisianthoides, and to provide data on their geographical distribution and habitat. Morphological and anatomical data were subjected to multivariate analysis. Schultesia pachyphylla is endemic to the state of Bahia, Brazil, and is separated from the other species by having 5-merous flowers, 5-winged calyx, wings between the calyx lobes, loss of interveinal tissue on sepals during fruit maturation, dark red colored immature calyces, capsules opening from base to apex, 3-anaporate pollen grains, and epidermal papillae evident in the field. Schultesia pachyphylla has amphistomatic leaves with anisocytic stomata, uniseriate epidermis, dorsiventral mesophyll, and bicollateral vascular bundles. The stem has small wings, cortical and medullary parenchyma, and internal phloem. Foliar colleters and nectaries on leaves and stem were observed. We believe that morphological and anatomical data could support the creation of a monotypic genus or the relocation of this species into another genus. Phylogenetic analyses are in progress to define the species' positioning. [ABSTRACT FROM AUTHOR]

• Glands at the leaf tooth apex in loquat are colleters of the standard type. • Polysaccharides, pectins and proteins was confirmed in the colleter exudates. • Phenolic compounds accumulated as glands age and cease exudate production. • An abscission zone at the base of the colleter is responsible for the falling of older non-secreting colleters. Several representatives of Rosaceae are characterized by presenting leaf teeth. These projections on the leaf margins may be associated with different secretory structures such as extrafloral nectaries, hydathodes or colleters. Colleters are the secretory structures far less kwon in Rosaceae. Although colleters were previously mentioned in species from subfamily Amygdaloideae, authors fail to provide a detailed morphoanatomical description and the chemical nature of the secretion for those colleters. Therefore, we aimed to morphoanatomically describe the leaf teeth of Rhaphiolepis loquata , confirming the nature of the gland associated with the teeth and shedding light on the chemical composition of the gland exudates. For that, samples from the leaf margins at different stages of development were collected and fixed according to standard techniques for both light and scanning electron microscopy. The leaf teeth in R. loquata presented a colleter at its apex. Colleters were rounded with covered by single- or doubled-layered secretory palisade covered with thick cuticle and the central axis was made up of parenchyma cells. The presence of polysaccharides, pectins and proteins was confirmed in the exudates and phenolic compounds accumulated as the gland aged and ceased the exudate production. An abscission zone at the base of the colleter was observed what could cause the falling off of older, non-secreting colleters. This is the first study on the chemical composition of colleter exudates as interpreted through histochemical tests, being a novelty not only for R. loquata but for the Rosaceae family. [ABSTRACT FROM AUTHOR]

Clusiaceae species are known globally for the economic importance of their secretory structures; however, reports of colleters in the family are scarce. In the present study, we characterised the leaf colleters in Clusia burchellii by investigating the morphology and anatomy of the glands, the histolocation of the major chemical substances present in the secretory cells and the cellular aspects associated with the synthesis and release of the secretion. Leaf samples at different developmental stages were collected and examined under light and electron microscopy. Histochemical tests were performed. Colleters of the standard type occur at the base of the petiole, are sessile or short pedunculated, and originate from protoderm and ground meristem cells. During leaf development, young, active, and whitish colleters become brownish and inactive at late developmental stages. Alkaloids and phenolic compounds were common in central axis cells. A mixture of hydrophilic and lipophilic substances histochemically detected, which can prevent water loss under hot tropical climates, were also found. Secretion accumulation was observed in the periplasmic region of the secretory cells and in the subcuticular spaces. Cuticular pores were present especially in the apical portion of the colleters. Our data revealed some cellular aspects of the secretion mechanisms in the leaf colleters of C. burchellii. [ABSTRACT FROM AUTHOR]

• This is the first description of colleters in Violaceae. • Trichomes, colleters, and mesophyll features allow species to be distinguished. • The morphoanatomical characters reflect the adaptability of the species to the Cerrado. • The anatomical data highlight the taxonomic potential of anatomy in future analyses of additional Pombalia and Hybanthus species. As traditionally circumscribed, Hybanthus Jacq. was the third-largest Violaceae genus, and the circumscription of its 9-10 lineages has been very problematic, particularly Pombalia Vand.. This largest and most heterogeneous segregate genus includes a phylogenetically strongly supported subclade exclusive of the Brazilian Cerrado known as Pombalia lanata complex comprising six species. Though this complex is readily distinct due to its adaptations to the Cerrado environment, the often sympatric species exhibit a high degree of superposition in its features, hampering their precise identification. Here, we aim to verify the taxonomic value of leaf anatomy for the species of the Pombalia lanata complex, comparing them to its sister group Pombalia calceolaria. An additional goal was to identify characters related to the adaptation of these species to the constraining environmental conditions of the Cerrado. Expanded leaves (field-collected and herbarium materials) were processed using light and scanning electron microscopy and histochemistry. The species present diminutive and densely hairy leaves, with simple or branched (stellate) trichomes, colleters, uniseriate and mucilaginous epidermis and prismatic calcium oxalate crystals. Among these characters, the distribution and morphotype of tector trichomes, and presence of marginal colleters are potentially useful in distinguishing the species of the complex. The remaining anatomic characters are mostly effective in circumscribing the complex as a whole, and reinforce the proximity to its sister group P. calceolaria. Moreover, such characteristics reflect adaptative strategies to the unique Cerrado conditions of high temperatures and solar irradiance, severe seasonal water shortfall, low humidity, and nutrient-poor soils with high aluminum content. This is the first description of colleters in Violaceae, opening perspectives in studies with secretory structures in the group. Our work highlights the potential of anatomy in taxonomic studies, which can be applied to Pombalia s. str. and the remaining lineages of Hybanthus s.l. [ABSTRACT FROM AUTHOR]

• The colleters of Prepusa have a secretory portion with homogeneous cells. • The colleters have intercellular spaces which accumulate polysaccharides and proteins. • The presence of phenolic compounds is associated with senescence of the colleters. • Congeneric species have alterations in secretion composition. Although the Atlantic Forest is considered a humid environment, plants that grow on rock outcrops present adaptive strategies, which correlate with tolerance to desiccation. Colleters are secretory structures that protect meristems and developing organs from dehydration and attack by herbivores or pathogens. Colleters are common in Gentianaceae; however, there is little research from an anatomical perspective. This study evaluated three Prepusa species (P. connata, P. hookeriana, and P. viridiflora) that are endemic to rock outcrops associated with the Atlantic Forest to investigate the distribution, anatomy, and histochemical composition of secretion of the their colleter throughout leaf growth and maturation. Samples of young, mature, and senescent leaf bases were collected, fixed, and processed following routine techniques in anatomical and micromorphological studies. In the three species, the colleters are located at the base of the leaves, on the adaxial surface. They are non-vascularized and have a short peduncle and a multicellular secretory portion coated by the cuticle. They develop asynchronously, as they are active in young leaves, and cease their activity in fully expanded leaves, but they are not deciduous. They have intercellular spaces, in which polysaccharide and protein secretions accumulate. Moreover, lipids were observed only in P. hookeriana and P. connata. Phenolic compounds are common and occur during colleter senescence, which is characterized by total cell collapse. Even though this study examined congeneric species from similar environments, the results confirm alterations in secretion composition and structural and chemical changes throughout leaf growth and maturation. [ABSTRACT FROM AUTHOR]