A systematic histological study of palm fruits. III. Subtribe Iguanurinae (Arecaceae)

This study represents a preliminary sampling of the pericarp histology of the subtribe Iguanurinae (tribe Areceae, subfamily Arecoideae) of the family Arecaceae. At least one sample from each of the 27 recognized genera was examined and illustrated with a line drawing. This sampling serves to characterize fruit structure in the subtribe as a whole, to illustrate the diversity of pericarp adaptations found in the subtribe, to characterize the monotypic genera, to provide hypotheses about the characterization of the larger genera, and to test existing phylogenetic hypotheses about the Iguanurinae. There are no unique tissues present in the pericarp in this subtribe, but genera can be readily characterized by unique combinations and distributional patterns in common tissues. These patterns, and some prominent evolutionary trends, parallel those in related subtribes of Areceae, such as the Ptychospermatinae and Arecinae. Significant in this subtribe is variation in the distribution of tanniniferous cells, raphide-bearing cells and brachysclereids, in the sculpturing of the seed and the locular epidermis, in the thickness of the locular epidermis, in the thickness of the fibrous vascular bundle sheaths, and especially in the number, orientation and distribution of nonvascular fibrous bundles. One major trend is the formation of systems of separate fibrous bundles and their progressive displacement toward the outer layer of the fruit, where a complex exocarp may form. The diversity of pericarp structure in the Iguanurinae is far greater than in the two subtribes previously studied.     

A systematic histological study of palm fruits. V. Subtribe Archontophoeniciae (Arecaceae)

Pericarp histology in the Archontophoenicinae provides little to characterize the subtribe as a whole, revealing instead two separate trends with parallels in other subtribes of the Areceae. The data support a close relationship among the three genera occurring in New Caledonia:Chambeyronia, Actinokentia, andKentiopsis, in which there is a complex endocarp consisting of short, oblique fibrous bundles embedded in a thick mantle of brachysclereids, and a loose endocarp of heavily fibrous, flattened vascular bundles adjacent to a relatively thin locular epidermis. The data also support a close relationship between the two genera of the New Zealand/Tasman Sea region:Hedyscepe andRhopalostylis, in which the pericarp is more or less fibrous throughout, with purely fibrous bundles in the outer pericarp and heavily fibrous vascular bundles in the inner pericarp. These results confirm relationships revealed by other morphological data.Archontophoenix appears to be most like the New Caledonian genera in its pericarp structure, with a similar mantle of short fibrous bundles embedded in a a mantle of brachysclereids in the outer pericarp, although it differs significantly in other aspects of morphology and anatomy.     

A systematic histological analysis of palm fruits VII. The Cyrtostachydinae (Arecaceae)

Fruit specimens representing five taxa of the genusCyrtostachys were examined histologically in order to characterize the pericarp anatomy of the monogeneric subtribe Cyrtostachydinae (tribe Areceae, subfamily Arecoideae), as part of an ongoing survey of the family. The pericarp in this genus can be characterized by a combination of papillate epidermis, heavy layer of tanniniferous/pigmented cells below the epidermis, a system of vascular bundles with thick fibrous sheaths with purely fibrous bundles frequently above and below, absence of brachysclereids, and a very thin sclerified locular epidermis. On the basis of pericarp structure alone, the genus might be most closely related to theGronophyllum alliance of the subtribe Arecinae. This diverges somewhat from the hypothesis of relationship with theAreca group of the Arecinae resulting from two DNA-based phylogenetic studies, and even further from the hypothesis of relationship withIguanura suggested by another DNA-based phylogenetic study.     

A systematic histological study of palm fruits. VIII. Subtribe Dypsidinae (Arecaceae)

Analysis of the pericarp structure in the four genera of the palm subtribe Dypsidinae reveals tissues similar to those in other taxa within the pseudomonomerous Indo-Pacific arecoid palms, but generally in unspecialized configurations consistent with their presumed basal position within this group. Unique tissues within some members of genus Dypsis include thin-walled, tannin-filled fibers around the vascular bundles. Large-fruited members of the presumably related genera Lemurophoenix, Masoala, and Marojejya show more distinctive arrangements of protective tissues and are quite different from one another. Only Marojejya appears to be closely related to Dypsis. Lemurophoenix and Masoala, by possession of both unsheathed vascular bundles and bundles with heavy fibrous sheaths, show possible affinities with genera well-removed from Dypsis.     

A survey of ontogeny pericarp features as contribution to the infratribal characterization of Myrteae (Myrtaceae)

With the aim of correlating the pericarp structure with current phylogenies of Myrteae, this study describes the ontogeny in five species included in five out of the six South American clades of the tribe. In these taxa, the outer and inner ovarian epidermis gives rise to the exocarp and the endocarp, respectively, both with 1 layer. In the mesocarp, derived from the ovarian mesophyll, secretory cavities are arranged into a circle just below the exocarp and near the endocarp in Campomanesia adamantium; only below the exocarp in Eugenia pitanga and Myrcia multiflora; more internally in Myrciaria cuspidata, and below the exocarp and throughout the mesophyll in Myrceugenia alpigena. The promising traits for phylogenetic studies in the group include: direction of elongation of pericarp layers, regions that develop most in relation to the circle of larger vascular bundles, differentiation of spongy and sclerenchymatous tissues and position of secretory cavities.     

A systematic histological study of palm fruits. IV. Subtribe Oncospermatinae (Arecaceae)

Pericarp histology in the Oncospermatinae reveals distinctive characters at the generic level but no unique characters at the subtribal level. Pericarp structure is diverse but parallels the diversity found in other subtribes of the Areceae. The subtribe appears to be divisible into two distinct groups: one in which sclereids alone provide the primary protective barrier in the outer fruit and one in which fibrous bundles, some-times in combination with brachysclereids, form the outer barrier. This division of the subtribe supports similar conclusions derived from morphological data.     

Pericarp structure and phylogeny within Lamiaceae subfamily Nepetoideae tribe Ocimeae

The pericarp structure has been investigated in about 205 species, representing 43 out of the about 50 genera of Lamiaceae subfamily Nepetoideae tribe Ocimeae (Ocimoideae). In its basic structure, the pericarp of Ocimeae corresponds to that of other Nepetoideae. The exocarp has usually both mucilaginous and non-mucilaginous cells. Below it, there are soft cells (mesocarp), a layer of vertically arranged bone cells and a thin innermost cell layer. The differences discovered in pericarp anatomy essentially agree with the traditional subdivisions of Ocimeae (by e.g. Briquet). The subtribes Hyptidinae and Ociminae and the genus Aeollanthus (in subtribe Plectran-thinae) have, with few exceptions crystals in the bone cells. Unlike other Labiatae, Plectranthinae (except Alvesia, Isodon and Siphocranion ) has a plate-like content in the mucilaginous cell. The systematic position of the latter three genera is discussed. Because of their pericarp anatomy, Hoslundia, Fuerstia, Catoferia, Nosema, Benguellia, Octomeron and Ceratanthus are suggested to belong to Ociminae, and Neohyptis to Plectranthinae. On the basis of pericarp characters an informal division of Ociminae is suggested. Considering the distribution of stamen and pericarp characters, the genera Capitanya, Pycnostachys and Solenostemon are suggested to originate from Plectranthus. Ocimeae species which grow in arid habitats tend to produce more mucilage and to have a larger plate-like content in the mucilaginous cells than species from moist or wet habitats.     

Seed and fruit anatomy ofCocculus hirsutus (Menispermaceae)

The ovules ofCocculus hirsutus are anatropous, bitegmic and, crassinucellate. The fruit is drupaceous, black purple, and laterally compressed and has a pericarp demarcated into exocarp and endocarp. The seeds are curved around the basal bodies. Testa and tegmen cells are thin-walled and unspecialized. In the ripe seed the inner epidermis of the tegmen persists, whereas the entire testa and the outer layer of the tegmen degenerate. Relationships of theMenispermaceae toRanunculaceae, Berberidaceae, andLardizabalaceae are supported.     

Pericarp histogenesis and histochemistry during fruit development in Butia capitata (Arecaceae)

Palm fruits show great structural complexity, and in-depth studies of their development are still scarce. This work aimed to define the developmental stages of the fruit of the neotropical palm Butia capitata and to characterize the ontogenesis of its pericarp. Biometric, anatomical, and histochemical evaluations were performed on pistillate flowers and developing fruits. The whole fruit develops in three phases: (I) histogenesis (up to 42 days after anthesis – DAA), when the topographic regions of the pericarp are defined; (II) pyrene maturation (42 to 70 DAA), when the sclerified zone of the pericarp is established; and (III) mesocarp maturation (70 to 84 DAA), when reserve deposition is completed. During pericarp ontogenesis (i) the outer epidermis and the outer mesophyll of the ovary give origin to the exocarp (secretory epidermis, collenchyma, parenchyma, sclerenchyma, and vascular bundles); (ii) the median ovarian mesophyll develops into the mesocarp, with two distinct topographical regions; (iii) the inner ovarian epidermis originates the endocarp; and in the micropylar region, it differentiates into the germination pore plate, a structure that protects the embryo and controls germination. (iv) Most of the inner region of the mesocarp fuses with the endocarp and, both lignified, give rise to the stony pyrene; (v) in the other regions of the mesocarp, carbohydrates and lipids are accumulated in a parenchyma permeated with fiber and vascular bundles. The development of the B. capitata pericarp presents high complexity and a pattern not yet reported for Arecaceae, which supports the adoption of the Butia-type pyrenarium fruit class.

     

Pericarp anatomy and evolution inCoriaria (Coriariaceae)

The first overall study of pericarp anatomy ofCoriaria is presented to discuss its evolution and relationships within a genus. All 14 species investigated (including 11 narrowly defined species) have somewhat bilaterally flattened mature fruits with five to seven (or more) longitudinal costae. They share a usually nine-(or more-)cell-layered (at intercostal region), stratified mature pericarp, which is basically constructed by an exocarp, an outer, a middle and an inner zone of mesocarp, and an endocarp. While a multi-layered endocarp is composed of circumferentially elongate fibres, a multi-layered inner zone of the mesocarp comprises longitudinally elongate fibres. Despite its uncertain systematic value, the presence of those fibres arranged crisscross is a characteristic feature of the genus. Comparisons among species indicate thatCoriaria terminalis, a species of the Eastern Hemisphere, retains a basic or archaic, well-stratified pericarp structure similar to the one found in all the species investigated of the Southern and Western Hemisphere, and that four species of Asia,Coriaria napalensis, C. sinica, C. intermedia andC. japonica, share a specialized structure (lacking the outer zone of the mesocarp) indicative of their mutual close affinity. Comparisons further suggest distinctness ofCoriaria intermedia, as well as variously derived position ofC. myrtifolia andC. japonica.     

Pericarp structure and myxocarpy in selected genera of Nepetoideae (Lamiaceae)

The pericarp structure has been analyzed in 37 species representing 13 genera from four tribes of Nepetoideae (Lamiaceae). 11 species are endemics of Balkan Peninsula or other Mediterranean regions. Basically, the pericarp was similar to other Nepetoideae by having exocarp, mesocarp s. str., vertically arranged bone cells and thin innermost cell layer. The ratio between pericarp thickness and nutlet size was the highest in Mentha spp. According to this parameter Micromeria species belonging to different sections could be distinguished. Acinos spp. were characterized by the thickest sclerenchyma in ratio to pericarp thickness. Crystals were present within sclerenchyma region in genera Mentha, Melissa, Nepeta and Prunella . The mucilage production has also been tested. Most of the studied species produced mucilage when becoming wet. The strongest mucilage reaction showed Acinos and Prunella . Pericarp characters studied are of taxonomical interest. They were mainly correlated with the generic or infrageneric classification of some genera.     

Pericarp formation in early divergent species of Arecaceae (Calamoideae,Mauritiinae) and its ecological and phylogenetic importance

Lepidocaryum tenue, Mauritia flexuosa and Mauritiella armata belong to the subtribe Mauritiinae, one early divergent lineage of the Arecaceae and one of the few of Calamoideae that occur in South America. These species occur in swampy environments and have fruits that are characteristically covered with scales. The objective of this study was to describe the formation of the layers of the pericarp within this subtribe and attempt to correlate fruit structure with the environment where species typically occur. Toward this goal, flowers in pre-anthesis and anthesis and fruits throughout development were analyzed using standard methods for light microscopy. The ontogeny of the layers of the pericarp of all three species was found to be similar. The scales were formed from non-vascularized emergences composed of exocarp and mesocarp. The median mesocarp accumulates lipids only in M. flexuosa and M. armata. The inner mesocarp together with the endocarp becomes papyraceous and tenuous in all species. This internal region of pericarp showed collapsed cells due to seed growth at the end of fruit development. Fruits of Mauritiinae are baccate, and the characters of the pericarp, especially the inner mesocarp and endocarp, help to maintain moisture. On the other hand, many species close to Mauritiinae show pericarp with sclerenchyma adjacent to the seed. This variation can contribute to understand the importance of this striking character in dispersal, germination and colonization in Arecaceae.     

Fruit structure of Amborella trichopoda (Amborellaceae)

The indehiscent fruitlets of the apparently basalmost extant angiosperm, Amborella trichopoda, have a pericarp that is differentiated into five zones, a thin one‐cell‐layered skin (exocarp), a thick fleshy zone of 25–35 cell layers (outer mesocarp), a thick, large‐celled sclerenchymatous zone (unlignified) of 6–18 cell layers (middle mesocarp), a single cell layer with thin‐walled (silicified?) cells (inner mesocarp), and a 2–4‐cell‐layered, small‐celled sclerenchymatous zone (unlignified) derived from the inner epidermis (endocarp). The border between inner and outer mesocarp is not even but the inner mesocarp forms a network of ridges and pits; the ridges support the vascular bundles, which are situated in the outer mesocarp. In accordance with previous observations by Bailey & Swamy, no ethereal oil cells were observed in the pericarp; however, lysigenous cavities as mentioned by these authors are also lacking; they seem to be an artefact caused by re‐expanding dried fruits. The seed coat is not sclerified. The fruitlets of Amborella differ from externally similar fruits or fruitlets in other basal angiosperms, such as Austrobaileyales or Laurales, in their histology. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 148 , 265–274.     

Development of ovule,fruit and seed of Xyris (Xyridaceae,Poales) and taxonomic considerations

The development of the ovule, fruit and seed of Xyris spp. was studied to assess the embryological characteristics of potential taxonomic usefulness. All of the studied species have (1) orthotropous, bitegmic and tenuinucellate ovules, with a micropyle formed by both the endostoma and exostoma; (2) a cuticle in the ovules and seeds between the nucellus/endosperm and the inner integument and between the inner and outer integuments; (3) helobial, starchy endosperm; (4) a reduced, campanulate and undifferentiated embryo; (5) a seed coat formed by a tanniferous endotegmen, endotesta with thick‐walled cells and exotesta with thin‐walled cells; and (6) a micropylar operculum formed from inner and outer integuments. The pericarp is composed of a mesocarp with cells containing starch grains and an endocarp and exocarp formed by cells with U‐shaped thickened walls. The studied species differ in the embryo sac development, which can be of the Polygonum or Allium type, and in the pericarp, which can have larger cells in either endocarp or exocarp. The Allium‐type embryo sac development was observed only in Xyris spp. within Xyridaceae. Xyris also differs from the other genera of Xyridaceae by the presence of orthotropous ovules and a seed coat formed by endotegmen, endotesta and exotesta, in agreement with the division of the family into Xyridoideae and Abolbodoideae. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 177 , 619–628.     

Pericarp anatomy of wild roses (Rosa L., Rosaceae)

The pericarp anatomy of representatives of all subgenera and sections of the genus Rosa was studied. All species have the same basic pericarp structure: it is composed of inner and outer endocarps, mesocarp and exocarp formed by the epidermis and hypodermis. The differences concern mainly the thickness of particular layers, and the shape and size of their cells. Cells of the endocarp and mesocarp are thick-walled. The only exception is Rosa rugosa mesocarp, which is composed of rather thin-walled cells with a large lumen. The endocarp structure of Rosa achenes resembles the drupe of the genus Prunus s.l. and drupelets of Rubus species.     

A phylogenetic analysis of the palm subtribe Oncospermatinae (Arecaceae) based on morphological characters

Subtribe Oncospermatinae (Arecaceae: Arecoideae: Areceae) is a diverse group of spiny Old World palms. The subtribe includesOncosperma, a widespread Asian genus of five species, along with seven monotypic genera, all endemic to the Seychelles and Mascarene Islands of the western Indian Ocean. A phylogenetic analysis was conducted in order to test the monophyly of subtribe Oncospermatinae with respect to other Old World genera of tribe Areceae. A matrix of 38 morphological characters was scored for 29 taxa, including 11 species of the Oncospermatinae. A single most parsimonious tree was found, resolving the subtribe as a polyphyletic group of two distinct clades. One clade containingAcanthophoenix, Deckenia, Oncosperma, andTectiphiala was placed as sister to a large group that includes members of subtribes Archontophoenicinae, Arecinae, Iguanurinae, and Ptychospermatinae. The other clade of Oncospermatinae, including the Seychelles endemic generaNephrosperma, Phoenicophorium, Roscheria, andVerschaffeltia, was resolved as sister to the Madagascar endemic subtribe Masoalinae, and may have arisen in the western Indian Ocean region.     

Morphological characters of leaf epidermis in schisandraceae and their systematic significance

The leaf epidermis of 23 species belonging to 2 genera within Schisandraceae was investigated using light and scanning electron microscopy. Many characters of the leaf epidermis in Schisandraceae, such as shape of epidermal cells, type of stomata, and cuticular ornamentation, are usually constant within species and thus helpful for elucidating the relationship between and within genera. Leaf epidermal cells are usually irregular or polygonal in shape. The patterns of anticlinal walls are straight, sinuolate, sinuous or sinuate. The stomatal apparatus belong to paracytic or laterocytic type and the latter is subdivided into various subtypes based on the number and arrangement of subsidiary cells. Under scanning electron microscopy observation, the cuticular membrane is often striated, sometimes squamulate or granular; the inner margin of the outer stomatal rim is nearly smooth or denticulate. Evidences from shape of epidermal cells, patterns of cuticular intrusions between the ends of each guard cell of a pair and distribution of stomatal apparatuses support the viewpoint thatKadsura is more primitive thanSchisandra. Study on leaf epidermis also shows thatKadsura interior deserves the rank of a distinct species and the treatment of the evergreen groups, includingS. propinqua andS. plena, as distinct from the deciduous species of the genus is quite natural.     

Development and structure of the pericarp and seed of Rhus lancea L. fil. (Anacardiaceae), with taxonomic notes

The pedicel of the female flower of Rhus lancea is distinctly articulated and usually carries three bracteoles. In the linear tetrad the micropylar megaspore forms the 8-nucleate embryo sac of the Oenothera-type. The single, bitegmic ovule is anatropous. The ripe, loose, papery exocarp consists mainly of the outer epidermis and a sclerified hypodermis. The mesocarp is not a typical sarcocarp, since the ridges and the inner layers are sclerenchymatous. The endocarp, originating from the inner epidermis, consists of four layers and its structure and microchemistry emphasize the close alliance of Rhus with other genera of the section Rhoideae. The endotestal seed indicates a phylogenetic affinity between the Anacardiaceae and the Burseraceae.     

Development and structure of the drupe in Sclerocarya birrea (Richard) Hochst. subsp. caffra Kokwaro (Anacardiaceae), with special reference to the pericarp and the operculum

The development and structure of the exo-, meso- and endocarp of the drupe of Sclerocarya birrea subsp. caffra were examined. The mature exocarp comprises the outer epidermis with stomata and lenticels, subepidermal collenchyma and parenchymatous layers with secretory canals. This exocarp sensu lato develops from the outer epidermis and the outer layers of the ovary wall. The fleshy parenchymatous mesocarp or sarcocarp also contains secretory tissue. The mesocarp develops after endocarp differentiation and lignification. The developmental sequence within the pericarp corresponds to the general pattern in drupes. The endocarp or sclerocarp, which is not stratified, consisting mainly of brachysclereids, fibres and vascular elements, develops from the inner epidermis and adjacent tissue of the young ovary wall including the procambium strands. The operculum represents a well-defined part of the endocarp. Early in its development a parenchymatous zone already clearly demarcates the operculum. The literature on the pericarp of the Anacardiaceae drupe is discussed to establish the diagnostic value of these morphological characteristics for future taxonomic studies.     

Embryology of tribeDrypeteae, an enigmatic taxon ofEuphorbiaceae

The tribeDrypeteae, whose traditional assignment inPhyllanthoideae ofEuphorbiaceae is now doubtful, is studied embryologically on the basis of a literature survey and examination of six additional species in two of the four constituent genera.Drypeteae are characterized by having several embryological features that are unknown in otherPhyllanthoideae, such as a two- or three-celled ovule archesporium; a thin, two cell-layered parietal layer in the nucellus; no nucellar beak or cap; an early disintegrating nucellar tissue; thick, multiplicative, inner and outer integuments; an endothelium; a few discrete vascular bundles in the outer integument; and a fibrous exotegmen (or its derived state). EmbryologicallyDrypeteae do not fit within thePhyllanthoideae and, as available nucleotide sequence data from therbcL gene suggest, are rather placed nearErythroxylaceae, Rhizophoraceae, Chrysobalanaceae, andLinaceae. Drypeteae share with those families a combination of the fibrous exotegmen, the endothelium, and the thick, multiplicative inner integument.