Exine Sculpture in Pariana Pollen (Gramineae)

Pollen grains of eieven species of Pariana, a small genus of herbaceous bamboos, were studied using LM, SEM and TEM. Ten of them have the Pariana stenolemma-type of pollen characterized by areolate exine due to relatively high and well separated denticulate processes on a slightly undulated tectum, vestigial columellae and no distinct annulus. At the pore edge the foot layer is thickened and folded.

P. campetris (P. campestris-type) shows this exine feature only at magnifications higher than x 2000, whereas the denticulate processes are clearly visible at x 400 magnification in the other ten species. The pores are bordered by a distinct annulus.

The high relief of the Pariana pollen forming a relatively rough surface would offer more friction in wind transport than the smooth surface of other grass pollen grains. Insects visiting the flowers have been observed which support the idea of possible insect pollination. If this would be the case, the parianas would be an example of correlation between pollen form and function in the evolution of the Gramineae.     

POLLEN PORE DEVELOPMENT AND ITS SPATIAL ORIENTATION DURING MICROSPOROGENESIS IN THE GRASS SORGHUM BICOLOR

The spatial relationships observed during microsporogenesis and pollen development in Sorghum bicolor indicate that a strong polarization exists in the anther locule and within individual microspores and pollen grains. During all developmental stages, each sporogenous cell and its derivatives lie continuously adjacent to the tapetum. The microspores and pollen grains form depressions in the tapetal orbicular wall. When the single pore of each microspore is initiated, as a gap in the primexine, it too lies adjacent to the tapetum and remains tightly appressed there until pollen maturity. A sequence of polar phenomena in microspores and pollen grains centers on an axis through the pore and perpendicular to the tapetal surface. These events include migrations of the microspore and vegetative nuclei, initial placement of the generative cell opposite the pore and its later migration, and a polar engorgement process whereby the pore end of the pollen grain (adjacent to the tapetum) fills with starch grains first. The tapetal cytoplasm completely degenerates at precisely the time of pollen engorgement, and its degradation products are believed to be available for pollen uptake at this time. The continuous association of the sporogenous cells or their cellular derivatives and their pores with the tapetum is thought to play an indispensible role in pollen development in sorghum and probably in all other grasses as well. The consistent position of the pore adjacent to the tapetum should be considered another common feature of microsporogenesis in the Gramineae. The characteristic exine pattern forms over the operculum and annulus of the pore, but the lamellae, which underlie the annulus, form a highly modified multilayered nexine. Membrane-like cores are observed in these lamellae and are believed to be involved in the initiation of sporopollenin deposition, but they are obliterated by pollen maturity. Neither the cores nor the lamellae are found in other parts of the pore or in the nonapertured wall.     

Cytochemistry of pollen development in Brachypodium distachyon

Brachypodium distachyon is a widely recognized model plant belonging to subfamily Pooideae with a sequenced genome. To gain a better understanding of the male reproductive development in B. distachyon we examined pollen morphology and cytochemical changes of microspore cytoplasm from pollen mother cell stage to mature pollen using light, fluorescent and scanning electron microscopy. Our results show that B. distachyon exhibits a typical monocot-type pollen ontogeny. Meiosis in the pollen mother cells is accomplished by successive cytokinesis generating isobilateral tetrads. Cytochemical examination indicated that microspore cytoplasm contains variable amounts of insoluble carbohydrates and proteins at different developmental stages. Deposition of starch in the cytoplasm of microspores starts at the bicellular stage and continues till the mature pollen stage. The formation of the exine wall progresses by the deposition of sporopollenin from the tapetum layer of the anther. The mature pollen is trinucleate, spheroidal in shape and possesses a single pore with an annulus and operculum. The exine pattern is smooth and of granular type.     

Why does some pollen lack apertures? A review of inaperturate pollen in eudicots

Apertures are key characters of pollen grains with systematic importance in angiosperms. They function as sites for pollen tube exit, water uptake, transfer of recognition substances and accommodation of volume changes. Not all pollen has apertures; inaperturate pollen (lacking obvious apertures) characterizes many angiosperm groups, especially in early divergent angiosperms and monocots, but also eudicots. In order to expand our knowledge of the systematic distribution, possible functional significance and development of inaperturate pollen in angiosperms, this review focuses on inaperturate and cryptoaperturate (with hidden apertures) pollen in the large eudicot clade, which comprises about 75% of present‐day angiosperm species. It includes new TEM observations of inaperturate pollen from four exemplar taxa selected from different parts of the eudicot phylogeny. Two categories of inaperturate (including cryptoaperturate) pollen occur in eudicots. (1) Sterile attractant or feeding pollen associated with functional dioecy has evolved iteratively at least six times in conjunction with complex breeding systems in the core eudicots. (2) Fertile pollen has evolved numerous times independently throughout eudicots, though generally in a relatively small number of individual taxa. Notable exceptions are the petaliferous crotonoid Euphorbiaceae s.s., in which fertile inaperturate pollen occurs in c. 1500 species, and two subfamilies of Apocynaceae s.l. (Secamonoideae and Asclepiadoideae) with c. 2500 species with fertile inaperturate pollen in pollinia. Fertile inaperturate pollen is sometimes (but not always) associated with an aquatic habit, parasitism, insectivory, heterostyly, anemophily or pollinia. Most fertile inaperturate pollen has a thin exine, or the exine is largely restricted to isolated components (muri, protuberances, subunits) separated by thinner areas which probably function as apertures. In cryptoaperturate pollen, the aperture is covered by continuous exine which probably has a protective function, similar to an operculum. Developmentally, inaperturate pollen is not associated with any particular tetrad type or meiotic spindle orientation (unlike some apertures) due to the absence of a colpal shield of endoplasmic reticulum or other organelles and hence is independent of microsporogenesis type. The lack of a colpal shield during the tetrad stage of development permits complete deposition of first primexine and then exine around each microspore, possibly mediated by the action of the DEX1 protein. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155 , 29–48.     

THE POLLEN WALL OF CANNA AND ITS SIMILARITY TO THE GERMINAL APERTURES OF OTHER POLLEN

The pollen wall of Canna generalis Bailey is exceptionally thick, but only a minor part of it contains detectable amounts of sporopollenin. The sporopollenin is in isolated spinules at the exine surface and in the intine near the plasma membrane. There is no sporopollenin in the > 10 μ thick channeled region between spinules and intine. We suggest that the entire pollen wall of C. generalis is similar to the thick intine and thin exine typical for germinal apertures in many pollen grain types. Considered functionally, the Canna pollen wall may offer an infinite number of sites for pollen tube initiation and would differ significantly from grains that are inaperturate in the sense of an exine lacking definite germinal apertures.     

POLLEN GRAIN DEVELOPMENT AND TAPETAL CHANGES IN STRELITZIA REGINAE (STRELITZIACEAE)

The proexine that forms within the callosic envelope before the end of the microspore tetrad period is thick (about 1 μm) and exceptionally complex. It has components equatable with tectum, columellae, and a nexine that includes lamellar zones. All these components persist in the exine although late in development they become difficult to recognize because this exine is reduced in thickness, apparently by stretching, to a maximum of 0.2 μm. Strelitzia is an example of an exine template, with receptors for sporopollenin, that is not maintained during development. The Strelitzia microspore surface changes from an exine like that on an interaperture sector to the channeled intinelike system common for the apertures of pollen grains. The exine on sterile grains gives what may be a rare view of a stabilized immature exine. The mature exine on viable pollen grains resembles this early exine only in the most impressionistic way. Tapetal cells go through at least one cycle of hyperactivity, dedifferentiation, mitosis, and then again hyperactivity before they finally decline.     

Cupressus arizonica pollen wall zonation and in vitro hydration

The structure of Cupressus arizonica pollen at different degrees of hydration was examined by using cytochemical staining and light (LM) and scanning electron (SEM) microscopy. Most pollen grains are inaperturate and a minority are provided with an operculate pore enveloped by a concave annulus. Intine consists of: 1) a thin polysaccharidic outer layer, 2) a large polysaccharidic middle layer that is spongy and bordered by a mesh of large and branched fibrils, and 3) an inner cellulosic thick layer with callose concentrated on the inner side, which forms a shell around the protoplast. The protoplast is egg-shaped with PAS positive cytoplasm and prominent nucleus. Exine splits during hydration and is cast off according to three major steps: 1) the split opens like a mouth and the underlying intine is expelled by swelling like a balloon, 2) the protoplast enveloped by the inner intine is sucked in the outgrowing side, and 3) the backside of the intine gets rid of the exine shell. In water containing salts, exine is rapidly released and the middle intine may expand up to break the outer layer, with disgregation of the spongy material and release of the intine shell including the protoplast. In water lacking salts, the sporoderm hydration and breaking are negatively influenced by the population effect. Pollen when air dried after the exine release become completely flat owing to disappearance of the middle intine layer which may be restored by dipping pollen in water. The results are discussed in relation to the functional potentialities of the sporoderm.     

Aperture development in spores of the moss,Trematodon longicollis Mx.

Summary Young spores of the mossTrematodon longicollis Mx. are highly polar. Immediately after meiotic cytokinesis an extensive system of microtubules associated with the single plastid develops under the entire distal face. Following exine initiation on the distal surface a microtubule system is elaborated at the site of aperture development on the proximal surface. Both plastid and nucleus move from distal to proximal pole and are attached to microtubules of the proximal system. Microtubules underlie the plasma membrane as it withdraws from the exine in the initiation of both the surrounding annulus and central aperture pore. The central pore enlarges to form a bowl-shaped concavity in which a fibrillar plug develops basipetally. The annulus expands into a fibrillar-filled protrusion surrounding the central pore. The mature aperture consists of a central pore plug covered by a thin roof of exine and separated from the surrounding annulus by exine lamellae. The aperture of the mature spore is obscured by development of the ornate exine and is not a prominent feature of the mature spore surface.     

A Ploidy-Sensitive Mechanism Regulates Aperture Formation on the Arabidopsis Pollen Surface and Guides Localization of the Aperture Factor INP1

Pollen presents a powerful model for studying mechanisms of precise formation and deposition of extracellular structures. Deposition of the pollen wall exine leads to the generation of species-specific patterns on pollen surface. In most species, exine does not develop uniformly across the pollen surface, resulting in the formation of apertures–openings in the exine that are species-specific in number, morphology and location. A long time ago, it was proposed that number and positions of apertures might be determined by the geometry of tetrads of microspores–the precursors of pollen grains arising via meiotic cytokinesis, and by the number of last-contact points between sister microspores. We have tested this model by characterizing Arabidopsis mutants with ectopic apertures and/or abnormal geometry of meiotic products. Here we demonstrate that contact points per se do not act as aperture number determinants and that a correct geometric conformation of a tetrad is neither necessary nor sufficient to generate a correct number of apertures. A mechanism sensitive to pollen ploidy, however, is very important for aperture number and positions and for guiding the aperture factor INP1 to future aperture sites. In the mutants with ectopic apertures, the number and positions of INP1 localization sites change depending on ploidy or ploidy-related cell size and not on INP1 levels, suggesting that sites for aperture formation are specified before INP1 is brought to them.     

The Apertural Wall in Pollen of Linum grandiflorum

The apertural wall in tricolpate pollen of Linum grandiflorumwas investigated in order to understand its functioning duringdesiccation and rchydration. Whole and sectioned pollen grainswere studied with light or electron microscopy and by cytochemicalmeans. The areas of the apertures were examined in fresh drypollen, in grains moistened on agar gel or removed from compatiblestigmas, and in pollen from mature undehisced anthers The intine was found to consist of an inner ß-glucanlayer and an outer pectic layer. At the apertures the pecticlayer is thickened and overlaid by a ß-glucan layer.The pectinaceous intine stains red with basic fuchsin. The presenceof a third wall layer, the medine, was not confirmed. The aperturalintine thickenings possess considerable imbibitional capacityand at rehydration they appear as swollen lenticular bodies A procedure is described for obtaining intact exine free grains(EFG's) and whole, separated exines of L. grandiflorum. Invariably,the released EFG's consisted of protoplasts encased in the cellulosicintine. In most grains the outer intine remained attached tothe separated exine In L. grandiflorum the outer wall of the aperture expands whilethe protoplast and endintine are still infolded. Apparently,the exintine becomes detached from the endintine during desiccationand re-attaches at rehydration. It is suggested that the transientdetachment controls the influx of water into the vegetativecell Except for morph-specific exine processes no differences instructure of the aperture wall or its functioning at rehydrationwere observed between pin and thrum grains Pollen wallM, apertures, exintine, exine free grains, rehydration, desiccation, Linum grandiflorum     

Release of proteins from the pollen wall of Linum grandiflorum

Summary The emission of proteins from the pollen wall of Linum grandiflorum stained with Coomassie blue was followed directly in moistened grains as well as in pollen prints. Within the first minute of the grain being moistened exine-borne proteins emerged from both inter-apertural and apertural sites; subsequently, proteins of a different nature were discharged from the apertures only. In a fraction of the grains the release of intine proteins was not preceded by that of exine proteins. Pin and thrum pollen did not differ in terms of mode or site of this protein emission. The presence and emergence of exine proteins from the apertures is explained by the process of infolding of the colpal wall at desiccation and its expansion at rehydration, which causes an initial trapping and subsequent re-exposure of surface materials. This explanation may also account for the occurrence of poral sporophytic proteins in the pollens of many dictoyledons.     

A histological study of microsporogenesis in Tarenna gracilipes (Rubiaceae)

We studied the microsporogenesis in Tarenna gracilipes (Hayata) Ohwi, with special attention to the mode of exine deposition and tapetum development. We based this research on light (LM), scanning electron (SEM) and transmission electron microscopic (TEM) observations of developing anthers of T. gracilipes, from the microspore mother cell stage towards anther dehiscence. Evidence is supplied that the microsporogenesis in T. gracilipes can be considered as simultaneous. Columellae, foot layer and tectum develop in a fibrillar matrix. Similar with earlier studies in Rubiaceae species, a single white line formed near the plasmalemma in the extra‐apertural region. The developing endexine dilated into several white line centered lamellae at the apertures. An annulus is formed around the inner surface of each pore. In the mature intine two strata can be distinguished. At the apertures thick onci are formed protruding through the apertures thereby forming papillae, a common feature in Rubiaceae. In Rubiaceae species amoeboid as well as secretory tapeta are reported. In T. gracilipes it is shown that the tapetum cells possess in all developmental stages characteristics of the secretory type. During microsporogenesis the tapetum cytoplasm undergoes considerable changes which may indicate cycles of hyperactivity. Sporopollenin deposition on the pre‐orbicules is mediated by white lines showing correlations with endexine, annulus and columellae ontogeny. These findings corroborate the idea that orbicule wall development can represent a model to study sporopollenin deposition. At anther dehiscence Ca‐oxalate crystals are released out of the ruptured septum cells into the locule, providing a possible visual signal for pollinators.     

Immunolocalisation of arabinogalactan proteins and pectins in Actinidia deliciosa pollen

Summary. The cell wall composition of germinating pollen grains of Actinidia deliciosa was studied by immunolocalization with monoclonal antibodies against arabinogalactan proteins (AGPs) and pectins. In ungerminated pollen, the JIM8 epitope (against a subset of AGPs) was located in the intine and in the cytoplasm, while the MAC207 epitope (against AGPs) was only located in the exine. After germination, the JIM8 and MAC 207 epitopes were located in the cytoplasm and in the pollen tube wall. The Yariv reagent that binds to AGPs was added to the germination medium inducing a reduction or inhibition in pollen germination. This indicates that AGPs are present in the growing pollen tube and play an important role in pollen germination. To identify the nature of the pectins found in pollen grains and tubes, four monoclonal antibodies were used. The JIM5 epitope (against unesterified pectins) was located in the intine, more intensely in the pore region, and along the pollen tube wall, and the JIM7 epitope (against methyl-esterified pectins) was also observed in the cytoplasm. After germination, the JIM5 epitope was located in the pollen tube wall; although, the tube tip was not labelled. The JIM7 epitope was located in the entire pollen tube wall. LM5 (against galactans) showed a labelling pattern similar to that of JIM5 and the pattern of LM6 (against arabinans) was similar to that of JIM7. Pectins show different distribution patterns when the degree of esterification is considered. Pollen tube wall pectins are less esterified than those of the pollen tube tip. The association of AGPs with pectins in the cell wall of the pollen grain and the pollen tube may play an important role in the maintenance of cell shape during pollen growth and development.Correspondence and reprints: Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal.     

Palynological survey of the subtribe Elephantopinae (Asteraceae, Vernonieae)

Despite the taxonomic value of pollen morphology within the tribe Vernonieae, a detailed study of the pollen of the subtribe Elephantopinae is still lacking. The pollen morphology of ten species, representing three of the four genera of the subtribe, Elephantopus, Pseudoelephantopus and Orthopappus, was studied with LM, SEM, and TEM. The pollen of all the species studied was found to be echinolophate, although the differences in aperture features and both sculpture and exine structure allowed recognizing two pollen types. The species of Elephantopus (except for E. elongatus) and Pseudoelephantopus share the regular or more or less regular ridges pattern, the colporate condition but with the ectoapertures little developed, and the acaveate exine structure. From the sculpture and the apertures, the pollen of Caatinganthus harleyi was found to be similar to that of Elephantopus and Pseudoelephantopus. The pollen morphology of the monotypic Orthopappus, which is shared with that of E. elongatus, was further investigated for the first time. We found that it differs from that of the other species in having an irregular pattern of ridges, colporate condition but with a well-developed ectoapertures, and caveate exine. Additional studies of the exine structure and apertures features, coupled with molecular phylogeny, are needed to understand the evolution of pollen characters and re-evaluate the intergeneric relationships within the tribe.     

国产爵床科芦莉花族植物的花粉形态

报道了国产爵床科Acanthaceae芦莉花族Ruellieae芦莉花亚族Ruelliinae 2属7种、假杜鹃亚族Barlerinae 1属3种和马蓝亚族Strobilanthinae 16属34种植物扫描电镜下的花粉形态.芦莉花亚族的地皮消属Pararuellia和喜花草属Eranthemum的花粉均为圆球形,具3孔或3孔沟,外壁为不同的网状结构; 假杜鹃亚族的假杜鹃属Barleria的花粉为长球形,具3孔沟,外壁亦为网状结构;马蓝亚族植物(包含广义的马蓝属Strobilanthes s.l.)花粉形态多样,结构复杂.依据花粉萌发孔和外壁纹饰特征,可将马蓝亚族16属植物和上述两亚族3属植物的花粉形态归纳成3大类型: 1. 具3孔类型.其中又有(1)外壁具网状纹饰者,见于地皮消属; (2)外壁具芽胞状纹饰者,见于黄猄草属Championella; (3)外壁具刺状(棒状)纹饰者,见于南一笼鸡属Paragutzlaffia、叉花草属Diflugossa和假蓝属Pteroptychia.2. 具3孔沟及具3孔沟与假沟类型(肋条带型).其中又有(1)具3孔沟和网状纹饰者,见于喜花草属和假杜鹃属; (2)具刺状(棒状)纹饰者,见于南一笼鸡属、叉花草属和假蓝属; (3)具3孔沟与假沟,外壁纹饰具节隔、肋条带状或网状,网眼纵向排列成行,网眼内有细网纹者,见于耳叶马蓝属Perilepta、马蓝属Pteracanthus(大部分)、金足草属Goldfussia、紫云菜属Strobilanthes(部分)和合页草属Sympagis; (4)具3孔沟与假沟类型,肋条带状,但不具节隔,外壁纹饰网状,网眼不成行或不明显纵向排列,网内无细网纹者,见于尖蕊花属Aechmanthera、板蓝属Baphicacanthus、马蓝属(部分)和糯米香属Semnostachya; (5)具双脊及细网状纹饰者,见于环毛紫云菜Strobilanthes cycla.3. 具(4-)5孔沟及假沟类型(肋条带型),外壁具网状或拟网状纹饰,见于腺背蓝属Adenacanthus.另外兰嵌马蓝属Parachampionella、山一笼鸡属Gutzlaffia和肖笼鸡属Tarphochlamys的花粉有无萌发孔尚不清楚,有待进一步研究.综上所述,芦莉花族植物的花粉形态具有较高的多样性,是重要的分类性状.利用花粉形态特征能较好地区分高级分类群如亚科、族以及亚族,有时也有助于阐明类群之间的相互关系,甚至也能用于区分属、种和阐明其关系.     

A new look at the acetolysis method

The acetolysis method intreduced byGunnar Erdtman is still a very welcome and highly successful technique in palynology. However, acetolysis destroys all pollen material with the exception of sporopollenin that forms the outer pollen wall, the exine. Modern palynology in its application to plant systematics and phylogeny must consider all sporoderm characters, not only those of the exine. The neglect of the intine may distort some principal palynological aspects. This is illustrated by cases of total breakdown or gross modification of thin exine structures (e.g. inBeilschmiedia, Strelitzia) and by the clarification of apertures (e.g.,Polyalthia, Fissistigma, Calluna). In our view the investigation of both acetolysed and non-acetolysed pollen is obligatory for a well balanced view of pollen structure and function.     

国产省藤属植物的花粉形态学

对国产棕榈科省藤属(Calamius L.)15种植物的花粉进行了光学和扫描电镜观察,其中12种为首次报道。省藤属的花粉均为两沟型花粉,外壁覆盖层多为网状纹饰(大喙省藤C．macrorrhynchus)或具穿孔(华南省藤C.rhabdocladus)。首次发现省藤属花粉的外壁纹饰存在穿孔和外壁疣状突起的类型(阔叶鸡藤C.pulchellus)以及皱波状突起的类型(长鞭省藤C.flagellum)。花粉的大小、形状、外壁纹饰、外壁是否有突起,外壁厚度和网状纹饰网眼的大小,对于省藤属的种级分类有较大的意义。     

Using palynomorphological characteristics for the identification of species of Alsinoideae (Caryophyllaceae): a systematic approach

Palynological characters of 18 species belonging to seven genera of the traditional subfamily Alsinoideae including Arenaria, Cerastium, Eremogone, Lepyrodiclis, Minuartia, Sabulina and Stellaria were studied in detail using light and scanning electron microscopy. Pollen grains of subfamily Alsinoideae are subspheroidal or prolate, pantoporate and 20.04 to 51.4 µm in size, prominent and sunken apertures uniformly distributed on the pollen surface. Two types of pollen grain ornamentation were observed, i.e. microechinate-punctate or microechinate-perforate. Echini are present on the surface of the pollen of all investigated species with medium, dense, or sparse echinodensity. These species exhibit variation in polar view, equatorial diameter, number of apertures, exine thickness, diameter of pore, appendages per pore, pore ornamentation, echini arrangement, echinidensity and shape of pollen. Based on qualitative characters, a dichotomous key has been developed for quick and easy identification. The present investigation contributes to the systematic approach using palynological characteristics and correct identification of species for members of subfamily Alsinoideae (Caryophyllaceae).     

Pollen morphology of endemic species of the Gonospermum Less., Lugoa DC. and Tanacetum L. complex (Asteraceae: Anthemideae) in the Canary Islands (Spain), and its taxonomical implications

The pollen of nine endemic taxa of the Gonospermum Less., Lugoa DC. and Tanacetum L. complex and of T. parthenium L. (introduced species from the Canary Islands) was studied using light and scanning electron microscopy with the aim of extending the knowledge of their morphology and to investigate whether pollen morphology may help clarifying the controversial taxonomy of these taxa. Twenty six populations in the Canary Islands (Spain) were studied and the following parameters were measured: polar axis (P), equatorial diameter (E), polar exine thickness (Ex1), length (L) and thickness (A) of the spines in the meridional optical section, exine thickness at the centre of the mesocolpium in the interapertural area (Ex2) and distance between spines (De) in the equatorial optical section. The studies show that the pollen of the three genera is very similar regarding shape, apertures, and ornamentation, but may be distinguished by size and exine thickness.     

Pollen morphology of the tribe Ruellieae (Acanthaceae) from

Pollen morphology of seven species in two genera in the Ruelliinae, three species in one genus in the Barlerinae and 34 species in 16 genera in the Strobilanthinae (Ruellieae, Acanthaceae), were observed under SEM. Pollen grains in Ruellieae, particularly in Strobilanthinae (including Strobilanthes s.l.) exhibit great diversity and are most eurypalynous in the family. In light of the aperture types and exine ornamentation patterns, pollen grains of the genera examined fall into three major types: 1. 3-porate pollen, which includes, (1) pollen with reticulate exine ornamentation (Pararuellia); (2) pollen with gemmate exine ornamentation (Championella); (3) pollen with echinate exine ornamentation (Paragutzlaffia, Diflugossa and Pteroptychia). 2. 3-colporate pollen or 3-colporate pollen with pseudocolpi, which includes, (1) 3-colporate pollen with reticulate exine ornamentation (Eranthemum and Barleria); (2) 3-colporate pollen with pseudocolpi and ribbed or banded, and septate exine ornamentation, the lumina rounded, finely reticulate inside and arranged in longitudinal rows (Perilepta, Pteracanthus, Goldfussia, Sympagis and some species of Strobilanthes); (3) 3-colporate pollen with ribbed or banded yet not septate exine ornamentation, the lumina neither distinctly rounded and finely reticulate inside, nor conspicuously arranged in longitudinal rows (Aechmanthera, Baphicacanthus, Semnostachya and some species of Pteracanthus); and (4) 3-colporate pollen with ribbed and finely reticulate exine ornamentation but with broader bands, each band with two ridges (Strobilanthes cycla). 3. (4-)5-colporate pollen with pseudocolpi and reticulate or ornate exine ornamentation (Adenacanthus). No distinct apertures were observed in three genera, Parachampionella, Gutzlaffia and Tarphochlamys. Pollen morphological characters in the Acanthaceae can be used not only to distinguish taxa of higher ranks (subfamily, tribe and subtribe) and elucidate their relationships, but sometimes can also be used to distinguish genera and species.