Epidermal and anatomical studies on Chrysophyllum L. (Sapotaceae) species of South-Eastern Nigeria

The epidermal characters of leaves and anatomical characters of petioles and young stems of some members of the genus Chrysophyllum, viz. C. albidum, C. perpulchrum, C. cainito, and C. delevoyi were analyzed to determine their diagnostic features. Paracytic stomata, crystal sand, prismatic crystals, secretory canals occurred in all the species. All the species are hypostomatic except C. perpulchrum. The midribs of all species have an open semi-circular vascular system except in C. cainito with a closed system. Midrib and petiole of C. albidum and C. cainito have non-glandular T-shaped trichomes. Accessory bundles are only seen in the petioles of C. delevoyi, and in the midribs of C. albidum and C. cainito. The midrib and petiole of C. delevoyi and C. albidum have a central bundle. Laticifers, prismatic and sand crystals occur mainly in the cortical cells, pith cells, xylem, phloem, and mesophyll. Lamina of all species studied showed uniseriate epidermis except C. cainito which has two layers of the adaxial epidermis. The stomatal index, the ratio of the spongy to palisade mesophyll thickness, the ratio of cortex thickness, outline, number, and arrangement of the vascular bundles in the midrib, petiole, and young stem differ and are valuable diagnostic features in Chrysophyllum. Bangladesh J. Plant Taxon. 28(1): 217-231, 2021 (June)

Studying of anatomic structure of Amaranthus retroflexus L. herb

Amaranthus retroflexus L. is a perspective medical plant. We studied anatomic structure specialities of its stems and leaves. We visualized anomocytic stomatas and simple thin-walled multicellular trichomes on both sides of leaves. Big amount of calcium oxalate druses and cells with crystal sand along leaf ribes were found in mesophyll. Many conducting bundles (xylem, phloem and sclerenchyma) were detected on sectional cross of culm. We didn’t detected sclerenchymatous belt, angular collenchyma, simple thin-walled multicellular trichomes and crystalic inclusions.

Comparative wood anatomy of eight tree species of Mimosa sect. Batocaulon (Leguminosae) distributed in Mexico and their taxonomic implications

The great diversity of the genus Mimosa and the difficulty in the circumscription of its species and varieties based on morphology have encouraged the search for characters in other sources of evidence such as wood anatomy, which provides characters of taxonomic importance. The main objective of this study was to identify characters with taxonomic value for Mimosa; we studied the wood anatomy of eight tree species in Mimosa sect. Batocaulon from Mexico: Mimosa acantholoba, M. bahamensis, M. benthamii, M. hexandra, M. leucaenoides, M. tejupilcana, M. tenuiflora, and M. texana belonging to eight series: Acantholobae, Bahamenses, Distachyae, Bimucronatae, Leucaenoideae, Plurijugae, Leiocarpae and Boreales, respectively. One stem fragment (80 cm in length) was collected at 80 cm above soil height, from three plants per species. Twenty-five measurements were taken per individual for 15 anatomical characters. Three species have ring-porous wood and five species have diffuse-porous wood; the species differ in colour, figure, in the prevalence of a certain type of axial parenchyma, in the tangential diameter of the earlywood vessels, in the number of vessels connected by confluent-aliform parenchyma, in the number of series of rays and in the presence or absence of crystal sand in the ray cells. These characters have taxonomic value at species level, but not at series level. At the section level, the presence of homocellular rays distinguished Batocaulon from other sections of the genus. Based on these results, we produced a wood anatomical identification key to the eight studied species.

Leaf anatomy of Cordiera sessilis (Vell.) Kuntze (RUBIACEAE)

A study on the leaf anatomy of Cordiera sessilis (Rubiaceae), a native medicinal shrub from Brazilian Cerrado was carried out to identify features that may be useful in species recognition. Leaves were collected, fixed and processed by usual techniques, and studied by light and electron microscopy. Quantitative analyzes of stomata and trichomes were performed. In addition to the typical anatomical characteristics of Rubiaceae leaves, two types of vascular patterns were identified in the petiole: in distal part, the vascular system is arranged cylindrically surrounded by sclerenchyma sheath and in proximal part the vascular system is arranged in U-shape coupled to sclerified cells. The micromorphological organization of leaf surface, epicuticular wax types, the petiole pattern and histochemical characteristics as the presence of druses, crystal sand and alkaloids and absence of raphides in the mesophyll, midrib and petiole are considerate representative characteristics of C. sessilis and may be useful in the species recognition.

Colleters in 10 species belonging to three tribes of Rubiaceae: morphoanatomical diversity and potential as useful characters for taxonomy

Colleters are common secretory structures in Rubiaceae. In this study, we describe colleter morphoanatomy and histochemistry in 10 species belonging to Chiococceae, Coussareae, and Psychotrieae tribes of Rubiaceae. Colleter morphoanatomy was analyzed by light and scanning electron microscopy. Microscopy analysis revealed that colleters were present on the stipule adaxial surface in all species. In the case of Palicourea marcgravii A.St.-Hil. and Chiococca alba Hitchc., colleters were also found on leaf primordia and at the stipule apex, respectively. Colleters were classified into three types: standard, bifurcated standard, and reduced standard. Further analysis showed that colleter epidermal cells are thin-walled and possess a thin cuticle, conspicuous nuclei located at the equatorial or basal region, and abundant cytoplasm. Intercellular spaces were found among epidermal cells in Chiococca alba, Coussarea triflora Müll.Arg., Coussarea verticillata Müll.Arg., Psychotria conjungens Müll.Arg., and Psychotria sessilis Vell. Crystalliferous idioblasts containing raphides were observed in the colleter central parenchymatous axis of all species, while crystal sand was found only in Chiococca alba. Histochemical tests revealed that colleter secretion is composed of a mixture of mucilage and protein. We conclude that colleter position, typological variation, presence of vascularization, and type of calcium oxalate crystals represent promising characters for future taxonomic and phylogenetic studies in Rubiaceae.

Towards uncovering evolution of lineage-specific calcium oxalate crystal patterns in Piperales

Piperales is among the largest and most diverse angiosperm orders (>4000 species), occurring broadly in tropical and temperate habitats. Twenty-four of the species from 12 genera, representing all lineages of Piperales, except the holoparasitic Hydnoraceae, display a mixture of leaf calcium oxalate crystal types found in previous studies of the two genera of Piperaceae subfamily Piperoideae (Peperomia Ruiz & Pav. and Piper L.). Crystal macropatterns, a result of varying leaf anatomies and diverse habitats, are investigated in a comparative way by using clearings and recent molecular phylogenetic hypotheses to trace crystal types and macropattern evolution. Ancestral character reconstruction reveals that the most recent common ancestor of Piperales had either crystal sand or druses or both and that prisms, raphides, and styloids are derived from the ancestral crystal type(s). These results are also recovered for both the ancestors of the perianth-less and the perianth-bearing Piperales. Raphides or druses are found in the two other subfamilies of Piperaceae (Verhuellioideae and Zippelioideae). Asaraceae and Lactoridaceae display crystal sand, whereas Aristolochia L. (Aristolochiaceae) species display mainly druses. Our crystal investigation, combined with ancestral character reconstruction, suggests that styloids, raphides, and prisms are derived within Piperales from crystal sand or druses.

Diversity of calcium oxalate crystals in Cactaceae

The occurrence of various types of calcium oxalate crystals was studied in 251 species and subspecies of Cactaceae to determine whether they are useful characters for Cactaceae systematics. Crystal hydration states were identified by X-ray powder diffraction and polarizing microscopy as monoclinic calcium oxalate monohydrate (COM) and tetragonal calcium oxalate dihydrate (COD). Ninety-eight percent of taxa studied contained either COM or COD crystals, or both. Different morphologies of crystals were further defined by light microscopy and scanning electron microscopy as druses, raphides, styloids (prisms), and crystal sand. In particular, the preponderance of one of the hydration states (COM or COD) was characteristic for certain Cactus subfamilies. Data showed that in Pereskioideae, Maihuenioideae, and Opuntioideae COM is predominant, while in Cactoideae COD prevails. In the remainder of Cactoideae, the crystals were quite variable. In tribe Hylocereeae, many species form both COM and COD as well. In the genera Hylocereus , Epiphyllum , Selenicereus , and Weberocereus , COM forms were almost exclusively represented by raphides together with different crystal forms in their epidermal cells. In the remainder of the Cactoideae, crystals did not follow any observable patterns. Development of crystallographic standards for identifying crystal forms microscopically is proposed for future crystal studies.

Research note:Autoradiography utilising labelled ascorbic acid reveals biochemical and morphological details in diverse calcium oxalate crystal-forming species

Many plant species accumulate calcium oxalate crystals in specialised cells called crystal idioblasts. In one species of crystal-forming plants (Pistia stratiotes L.; forming raphide crystals), it has been shown that ascorbic acid is the primary precursor of oxalic acid. The question remains if this is true of other calcium oxalate crystal-forming plants. One way of answering the above question is by examining ascorbic acid as the oxalic acid precursor in diverse species with a variety of crystal types. In this study we tested ascorbic acid as the primary precursor of oxalic acid in four different species, each forming one of the four, thus far, unexamined crystal types: water hyacinth, styloid (and raphide); tomato, crystal sand; winged-bean, prismatic; water lily, astrosclereids with surface prismatic crystals. Pulse–chase feeding of 1-[14C]-ascorbic acid followed by resin embedding, microautoradiography and light microscopy were employed to examine incorporation of label into calcium oxalate crystals. For the species and crystal types studied, ascorbic acid is the primary precursor of oxalic acid and further, oxalic acid is added to crystals in patterns that correlate with the age and type of crystal involved.

Les cystides à cristaux des Inocybes (Agaricales): étude histochimique et cristallographique

Histochemical and cristallographic studies were performed in light microscopy and scanning electron microscopy on crystal-bearing cystidia of several Inocybe spp. (Agaricales) and confirmed the excretory function of these sterile cells of the hymenium. At the apex of these bottle-like cells, the wall had an axial polysaccharidic matrix rich in carboxyl groups. It also presented an enhanced permeability and a local concentration of Ca2+. Functioning as an hydathode, the cystidium secreted, at its apex, an aqueous droplet into which twin crystals developed. In addition, crystal sand were found in the cystidium wall. These two crystalline products were calcium oxalate as confirmed with anthracene green and the Pizzolato test. A detailed crystallographic study showed that these twin crystals undoubtedly belong to the monoclinic system, i.e., the monohydrated form of the calcium oxalate or whewellite. In the case of Inocybe asterospora Quél., these grouped crystals were formed regularly by two pairs of twin crystals. The identification and localization of the Ca2+ ions have been determined with the scanning electron microscope by means of the X-emission pictures and the resulting energy dispersive X-spectrum for the latter element. Key words: Inocybe, cystidium, hydathode, calcium oxalate, whewellite.