Leaf Epidermal Micromorphology Research Articles

Economically important species of Asteraceae: An overview of leaf epidermal micro-morphology with respect to water availability

This paper reports the result of a study undertaken with a view to documenting responses of leaf epidermal parameters of three economically important species of the family Asteraceae: Aspilia africana, Chromolaena odorata and Vernonia amygdalina from Nigeria to seasonal water stress. Obtained quantitative data showed a significant decrease (p < 0.05) in stomata density and index on the abaxial surface in Chromolaena odorata in dry conditions. The increased stomata densities and indices on the adaxial surfaces in Aspilia africana and Vernonia amygdalina in the wet season suggest that CO2 was more taken up. The reduction in stomata size (on both leaf surfaces in the three taxa) in the dry season indicated species' adaptations to dry conditions and reduction in stomatal conductance. Turgescent guard cell in the three species in the wet season indicated stomatal opening, which could, though, be a hormonal response to water availability since transpiration needed to be activated. The ability of Aspilia africana to reduce water loss and defend against herbivores greatly increased in plants that developed in dry conditions by possessing more multicellular trichomes in comparison to wet conditions, while in Vernonia amygdalina, the number increased during the wet season. Water stress had little or no effect on the micro-morphology of anticlinal walls and the shapes and arrangements of the epidermal cells in the three species. This study revealed that investigations into leaf epidermal micro-morphology might be a useful tool to elucidate the multiple mechanisms underlying leaf epidermal structure function in response to water availability.

The use of silicon and mycorrhizal fungi to mitigate changes in licorice leaf micromorphology, chlorophyll fluorescence, and rutin content under water-deficit conditions

In this study, the effects of water-deficit conditions, silicon (Si) fertilizer (300 ppm), and arbuscular mycorrhizal (AM) inoculation by Claroiedoglomus etunicatum were evaluated on several features of licorice (Glycyrrhiza glabra L.). The measurable features were photosynthetic parameters, rutin content in aerial parts, and leaf micromorphology. Drought was administered at five levels determined by the percentage of field capacity (FC), i.e. 100, 80, 60, 40, and 20% of FC. Leaf extracts were utilized for measuring rutin content (via HPLC), and photosynthetic pigments; measurement of stomatal density, and trichome analysis were performed by scanning electron microscopy (SEM). Under severe drought stress, leaf area decreased by 50.84%, compared to well-irrigated plants. A significant decrease in leaf numbers (32.52%) was observed because of deficit irrigation. AM and Si improved chlorophyll fluorescence, which corresponded to the maximum efficiency of photosystem II. Rutin content decreased significantly under deficit irrigation. Also, the integration of AM and Si treatments positively affected rutin quantity under various irrigation regimes. Under moderate stress (60% FC), using AM and/or Si treatments reduced the stomatal length by 61.22 and 52.98%, respectively. Interestingly, a significant reduction in stomatal density towards control was observed as a result of the integrated treatments of Si and AM (58.28% at W20 and 59.82% at W100), which helped plants reduce water loss when facing drought stress. Principal component analysis (PCA) showed that photosynthetic pigments, chlorophyll fluorescence, and rutin changed quantitatively under moderate drought stress, while more variations were observed in leaf epidermal micromorphology under severe drought stress. These findings revealed that Si and AM, by exogenous application, synergistically mitigated the effects of drought stress on licorice.

Leaf epidermal micromorphology of Zingiber (Zingiberaceae) from China and its systematic significance.

Leaf epidermal characteristics are important for phylogenetic and taxonomic studies of many plants, but there is currently insufficient such data for this application in Zingiber species. Therefore, the leaf epidermal micromorphology of 22 species in three sections of Zingiber was investigated by light microscopy and scanning electron microscopy. Differences between various taxonomic groups of Zingiberaceae were also compared to assess their phylogenetic and taxonomic significance. As in other genera of Zingiberaceae, the epidermal cells in both the adaxial and abaxial epidermis of Zingiber species were found to be hexagonal or polygonal, with non-sinuous anticlinal walls that are arranged parallel to leaf veins. Tetracytic stomata are mostly randomly distributed in the intercostal regions of both surfaces and are more common on the abaxial surface. The stomatal density of the species in sect. Pleuranthesis is significantly lower than that in sects. Zingiber and Cryptanthium. There are two types of trichome in Zingiber: so-called “delicate” trichomes are present in most species, while “stout” trichomes with a swollen base are only found in Z.corallinum and Z.montanum. Oil cells occur in both epidermal layers of some species in sects. Zingiber and Cryptanthium, but only in the abaxial epidermis of Z.ellipticum in sect. Pleuranthesis. Crystals are found in the abaxial epidermis only in all species, but are present in both epidermal layers of Z.corallinum and Z.montanum. Although the epidermal morphology is similar in most Zingiber species, stomatal density, type of trichome and distribution of oil cells and crystals offer valuable information for the systematic and taxonomic studies in this genus.

Two centuries from species discovery to diagnostic characters: molecular and morphological evidence for narrower species limits in the widespread SW Australian Anarthria gracilis complex (Restionaceae s.l./Anarthriaceae, Poales).

BackgroundThe extreme southwest of Australia is a biodiversity hotspot region that has a Mediterranean-type climate and numerous endemic plant and animal species, many of which remain to be properly delimited. We refine species limits in Anarthria, a Western Australian endemic genus characterised by the occurrence of the greatest number of plesiomorphic character states in the restiid clade of Poales. In contrast to many other groups of wind-pollinated Australian Poales, Anarthria was traditionally viewed as having well-established species limits. All six currently recognised species, which are conspicuous members of some Western Australian plant communities, were described in the first half of the 19th century. They are traditionally distinguished from each other mainly using quantitative characters.MethodsWe examined extensive existing herbarium specimens and made new collections of Anarthria in nature. Scanning electron microscopy and light microscopy were used to study leaf micromorphology. Molecular diversity of Anarthria was examined using a plastid (trnL-F) and a low-copy nuclear marker (at103). This is the first study of species-level molecular diversity in the restiid clade using a nuclear marker.ResultsMaterial historically classified as Anarthria gracilis R.Br. actually belongs to three distinct species, A. gracilis s.str., A. grandiflora Nees and A. dioica (Steud.) C.I.Fomichev, each of which forms a well-supported clade in phylogenetic analyses. Both segregate species were described in the first half of the 19th century but not recognised as such in subsequent taxonomic accounts. Anarthria dioica was first collected in 1826, then wrongly interpreted as a species of Juncus (Juncaceae) and described as Juncus dioicus. We provide a formal transfer of the name to Anarthria and for the first time report its clear and qualitative diagnostic characters: an extremely short leaf ligule and distinctive pattern of leaf epidermal micromorphology. A long ligule is present in A. gracilis s.str. and A. grandiflora. These species differ from each other in leaf lamina morphology and anatomy and have mostly non-overlapping distribution ranges. The narrower definition of species provides a basis for future phylogeographic analyses in Anarthria. Our study highlights a need for more extensive use of nuclear DNA markers in Restionaceae. The use of the low copy nuclear marker at103 allowed a clade comprising all three ligulate species of Anarthria to be recognised. The ligule character is used here for the first time in the taxonomy of Anarthria and merits special attention in studies of other restiids. In general, our study uncovered a superficially hidden but, in reality, conspicuous diversity in a common group of wind-pollinated plants in the southwest of Western Australia.

Taxonomic implications of leaf epidermis in halophytes of Amaranthaceae from Salt Range of Punjab, Pakistan

The leaf epidermal anatomy of 15 salt-tolerant plant species belonging to the Amaranthaceae from the Salt Range of Punjab-Pakistan was studied using light microscopy (LM). The main purpose of this investigation was to compare the leaf micro-morphologies of the studied taxa, which can provide diagnostic characters useful for correct identification of halophytic taxa. Various quantitative and qualitative foliar epidermal features of adaxial and abaxial surfaces, including epidermal cell shape, anticlinal wall pattern, lobes per cell, anomocytic, anisocytic, and paracytic types of stomata and trichome diversity, were studied. Eight types of trichomes reported for the halophytes studied i.e. stellate, glandular, conical, capitate, non-capitate, non-glandular, cylindrical, and falcate. The shapes of epidermal cells found are pentagonal, polygonal, irregular, wavy, and tetragonal. This is the first report on leaf epidermal micromorphology of halophytes of family Amaranthaceae of Salt Range of Punjab. The findings revealed that leaf epidermal features showed adequate variations among genera distinguishing the halophytic taxa of family Amaranthaceae.

Soil and foliar application of rock dust as natural control agent for two-spotted spider mites on tomato plants

Mineral-based products represent a valid alternative to synthetic pesticides in integrated pest management. We investigated the effects of a novel granite dust product as an agent for controlling two-spotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae), on tomato plants (Solanum lycopersicum L.). Two-choice tests for repellency and repulsiveness, and no-choice bioassays with different type of applications (soil, foliar, and soil–foliar) were used in order to evaluate performance and action of the product. Evaluation of epidermal micromorphology and mesophyll structure of treated plants and elemental analyses of leaves were performed. In repulsiveness experiments, almost all dust treatments significantly inhibited mites from migrating to and/or settling on the treated leaf. In repellency experiments, foliar and soil dust treatments were not significantly different from control. Significant mortality was observed for all dust treatments in two-choice and in no-choice bioassays, suggesting mites are susceptible to rock dust by contact, and by indirect interaction through the feeding on plants subjected to soil application of rock dust. Leaf epidermal micromorphology and mesophyll structure of treated plants showed structural variation due to mineral accumulation, which was also confirmed by elemental analyses of leaves. These results demonstrate for the first time that granite rock dust interacts with two-spotted spider mites by modifying pest behavior and via acaricidal action, providing more insights in understanding the mechanism of this novel natural product as pest management tool.

Studies in pharmacognostic characters of the climber <em>Erycibe paniculata</em> Roxb. of Convolvulaceae

The present scientific investigation deals with the pharmacognosy and preliminary phytochemical screening of the leaf and stem bark of Erycibe paniculata Roxb., an ethnomedicinal climber used in curing the fever, cholera, night blindness, sprains, constipation, etc. Standard methods have been followed to study the microscopic, macroscopic, physicochemical characters and fluorescence behavior of the powdered samples of this plant. Phytochemical screening including GCMS of the stem bark has also been performed. In leaf epidermal micromorphology, it was found that stomata are anisocytic type distributed in hypostomatic leaf. Stomatal Index was 13.879.Glandular unicellular type of trichomes found in both surfaces of the leaf. Non-glandular trichomes with 2 to 6-arms were observed on the epidermal surfaces of petiole and stem. Petiole in T.S. is semi-lunar in outline housing 3 vascular bundles. Total ash of the stem bark was found 9%, of which acid insoluble ash and water soluble ash values were observed 0.092% and 7.626%, respectively. Moisture content of the bark sample was 0.5%. Out of five solvent extractsofthe stem bark, methanolic extract showed highest extractive value (8.672%). Important groups of phytochemicals like tannins, alkaloids, flavonoids, etc. are detected in stem bark extract. Nine bioactive compounds have been identified through GCMS analysis from them ethanolic bark extract which, in turn, indicate its therapeutic properties. Present study provides the pharmacognostic characters of both leaf and stem bark of Erycibe paniculata which will be an instrumental in authentication and quality control of the crude drugs procured from this medicinal plant.

THE SYSTEMATIC SIGNIFICANCE OF LEAF EPIDERMAL MICROMORPHOLOGY OF TEN NEPENTHES SPECIES (NEPENTHACEAE) FROM PENINSULAR MALAYSIA

GHAZALLI, M. N., TAMIZI, A. A., ESA, M. I. M., BESI, E. E., NIKONG, D., NORDIN, A. R. M. & ZAINI, A. Z. 2019. The systematic significance of leaf epidermal micromorphology of ten Nepenthes species (Nepenthaceae) from Peninsular Malaysia. Reinwardtia 18(2): 81−96. — The pitcher plants of Malaysia belong to the genus Nepenthes and can be found thriving in swampy areas, along the roadside, on hillslopes and in mountainous terrains depending on species and their ecological preferences. In this study, cuticle micromorphology of ten species of Nepenthes (Nepenthaceae) collected from Peninsular Malaysia was intensively studied through scanning electron microscopy (SEM) to characterise and investigate diagnostic characters of cuticle micromorphology that can be useful in Nepenthes classification. A total of eleven characters from the inner and outer cuticles were enumerated in details and these characters have a value either for infrageneric classification or for diagnostic identification of the species. Characters observed and analysed were related to the epidermal cells, subsidiary cells, stomatal complex i.e type of waxes on both epidermal surfaces, abaxial and adaxial cuticular ornamentation, stomata characteristics, stomata formation, stomata frequency, cuticular ornamentation on stomata, shape of the stomata, stomata size, trichome existence and type of trichomes. Nepenthes ampullaria is clearly distinguished from the other species by markedly different types of tufted and multicellular trichomes of the epidermal cells on both leaf epidermal surfaces. For N. alba, its cuticular feature showed groovy cuticular pattern on the abaxial and adaxial surface, hence, can serve as a diagnostic cuticular pattern for this species. From these findings, the species delimitation based on cuticular features show a clear resolution, however some species might be individually distinct based on the combination of characters examined.

Leaf epidermal micromorphology and its implications in systematics of certain taxa of the fern family Pteridaceae from Northern Pakistan.

The present study is insights into foliar epidermal anatomy for characterizing clades, and their utility in taxonomic segregation of certain species of Pteridaceae from Northern Pakistan. The leaf epidermal anatomy of 10 species of Pteridaceae representing four genera were examined using light and scanning electron microscope. A micromorphological matrix was constructed for eight qualitative and 12 quantitative characters. unweighted pair group method with arithmetic means and principal components analysis statistical analysis were performed to test the validity of foliar epidermal anatomical features as method of separating species and genera, and phylogenetic clusters among species are constructed using qualitative and quantitative traits. The qualitative characters described here are shape of epidermal cells, stomata, guard cell and subsidiary cells, anticlinal wall pattern, and trichomes types which is helpful in defining groups within Pteridaceae. In addition, the size of stomata, guard cells, subsidiary cells, stomatal pore epidermal cells, and trichomes are quantitatively analyzed. All species have hypostomatic leaves. Two types of stomata were observed in studied species, anomocytic and polocytic. Anomocytic stomata were observed in three genera namely: Adiantum, Onychium, and Chielanthes whereas Pteris can be discriminated from other genera by its polocytic stomata. On the basis of multivariate analysis present study does provides sufficient information on the taxonomic importance of foliar anatomy which validate its efficacy in species and genera discrimination. From result obtained here it is further possible to use leaf micromorphologic data in ferns phylogeny and providing basis for future taxonomic delimitation in other taxa.

Comparative studies on leaf epidermal micromorphology and mesophyll structure of Elaeagnus angustifolia L. in two different regions of desert habitat

In order to obtain qualitative and quantitative characteristics of leaf epidermal micromorphology and mesophyll structure to evaluate the responses of Elaeagnus angustifolia L.to different environmental factors,epidermal micromorphology was observed by scanning electron microscopy(SEM),and mesophyll structure was studied by light microscopy(LM) and transmission electron microscopy(TEM).Materials were selected from Linze County,Gansu Province(material A) and Qitai County,Xinjiang Uygur Autonomous Region(material B) of China.Results show that lamina thickness was higher in material A,with one layer of epidermal cells in both adaxial and abaxial surfaces,and epidermal cell radial length was significantly longer in the adaxial surface.E.angustifolia leaves are typically bifacial,with a higher ratio of palisade to spongy tissue in material A.The thickness of trichome layer of epidermis was thicker in material A.In contrast,cell wall and cuticular wax of the epidermal cells were thinner in material A than in material B.Chloroplast ultrastructure was different with the approximate spherical chloroplast containing numerous starch grains and osmiophilic granules in material A,while only the spindly chloroplast contained starch grains in material B.Multiple layers of peltate or stellate-peltate trichomes occupied both leaf surfaces in material A and the abaxial surface in material B,while the adaxial surface of material B contained few trichomes.Stomata were not observed on the leaf surfaces in materials A and B by SEM because of trichome obstruction.Our results indicate that the leaf structure of E.angustifolia is closely correlated with environmental factors,and the combination of leaf epidermal micromorphology and mesophyll structure afford resistance to environmental stress.

The Classification of Bambusa spp. from Celebes Based on the Micromorphological Characters of Leaf Epidermis

Species of Bambusa had widespread in Celebes, especially for Bambusa striata and Bambusa vulgaris . As an effect of the lacking of flowering, species identification mainly depends on vegetative features, and leaf epidermal micromorphology has proven to be useful in bamboo taxonomy. The objective of this research was to describe the classification of Bambusa from Celebes based on the micromorphological characters of leaf epidermis. The specimens were collected from wild population. The samples of leaf were collected from five member of Bambusa i.e.: Bambusa blumeana , Bambusa maculata , B. striata , B. vulgaris and Bambusa sp. Micromorphological characters were identified using Scanning Electron Microscopy (SEM). Leaf epidermis characters separated B. blumeana from other species of Bambusa. Furthermore, B. striata were closely related to B. maculata in variation of bulliform cells. As an invention, we release peltate hair as a new type of trichome in Bambusa. The presence of various prickles, trichomes and bulliform cells may be especially useful in delimiting species.

The adaptive significance of differences of root morphology, anatomy and physiology from three ecotypes of reed (Phragmites communis Trin.)

Reeds are widely distributed in drought and high salt conditions of northwestern China. Leaf epidermal micromorphology, anatomy, chloroplast ultrastructure and physio-chemical characteristics due to long-term adaptation in the natural habitats of common reed ( Phragmites communis Trin.) contrasted considerably among three different ecotypes: dune reed (DR), Gobi salt reed (GSR) and swamp reed (SR). The main objective of the present study is to determine the adapting characteristics of morphology, anatomy and physiological responses of thin roots in DR, GSR and SR. The results show that root length density was higher in SR and few root hairs were observed in DR. Cross-section anatomical features show that each ecotype has an endodermis and exodermis, while cortex thickness and proportion of root cortical aerenchyma and stele in root structure varied among the three ecotypes. The stele and xylem share a larger area in DR compared to GSR and SR. GSR has a large proportion of the cortex with radialized distribution of aerenchyma cells spacing, and the cortex has a peripheral, mechanically stiff ring in the exodermis. SEM and TEM microscope images show that GSR has a sclerenchyma ring with high lignification in the exodermis. The physio-chemical parameters show that GSR had a higher level of stress tolerance than DR. These findings indicate that developed water-absorbing tissues were largely distributed in the root structure of DR, and a main framework with supporting function spacing with aerenchyma was dominant in GSR in the long term adaptation to their natural habitats, respectively.

Epidermal Micromorphology and Mesophyll Structure of Populus euphratica Heteromorphic Leaves at Different Development Stages.

Leaf epidermal micromorphology and mesophyll structure during the development of Populus euphratica heteromorphic leaves, including linear, lanceolate, ovate, dentate ovate, dentate rhombic, dentate broad-ovate and dentate fan-shaped leaves, were studied by using electron and light microscopy. During development of heteromorphic leaves, epidermal appendages (wax crystals and trichomes) and special cells (mucilage cells and crystal idioblasts) increased in all leaf types while chloroplast ultrastructure and stomatal characters show maximum photosynthetic activity in dentate ovate and rhombic leaves. Also, functional analysis by subordinate function values shows that the maximum adaptability to adverse stress was exhibited in the broad type of mature leaves. The 12 heteromorphic leaf types are classified into three major groups by hierarchical cluster analysis: young, developing and mature leaves. Mature leaves can effectively obtain the highest stress resistance by combining the protection of xerophytic anatomy from drought stress, regulation of water uptake in micro-environment by mucilage and crystal idioblasts, and assistant defense of transpiration reduction through leaf epidermal appendages, which improves photosynthetic activity under arid desert conditions. Our data confirms that the main leaf function is differentiated during the developing process of heteromorphic leaves.

Scanning electron microscopy of the leaf epidermis in Arundinarieae (Poaceae: Bambusoideae): evolutionary implications of selected micromorphological features

Arundinarieae (temperate woody bamboos) is a taxonomically challenging group and the taxa in this tribe show a low level of DNA sequence variation, especially for plastid markers. As a result of the scarcity of flowering collections, species identification mainly depends on vegetative features, and leaf epidermal micromorphology has proven to be useful in bamboo taxonomy. In this study, we used scanning electron microscopy to investigate the abaxial leaf epidermal micromorphology of 94 species in 24 genera of Arundinarieae and three species of Bambuseae. Leaf epidermal characteristics differed mainly in the number and distribution pattern of papillae. Seven papilla forms were assigned, which had little taxonomic value at the generic and subtribal levels. However, the papilla patterns combined with other leaf epidermal features were useful in the discrimination of several species. Most papilla types were shared between tribes Arundinarieae and Bambuseae. We assessed the phylogenetic implications of the leaf epidermal micromorphology based on recently published molecular phylogenetic analyses. With one exception, none of the papilla types corresponded to a particular clade in the plastid or nuclear phylogenetic trees. Based on these results, the papilla patterns have limited phylogenetic value. (C) 2014 The Linnean Society of London

Leaf Comparative Anatomy of Styrax(Styracaceae) in Hunan

The leaf epidermal micromorphology and anatomical structures of ten species in the genus Styrax from Hunan province in China were examined and statistically analyzed under light microscopy and scanning electron microscopy( SEM). The results were as follows:( 1) The epidermis was composed of a single layer of cells which are polygonal or irregular in shape and their anticlinal walls are straight,arched,or sinuous;( 2) The size and density of stomata apparatus between species are significantly different;( 3) The inner margin of the outer stomatal rim of stomata apparatus is nearly sinuolate or sinuous,and the cuticular ornamentation around stomata apparatus is characteristically distinguished by the bird's nest-like cuticular ornamentation of S. tonkinensis and the bowl-shaped cuticular ornamentation of S. suberifolius;( 4) The T-shaped thickening at either polar region of stomatal guard cells is found in S. hemsleyanus,S. dasyanthus and S. faberi;( 5) The upper epidermis of S. suberifolius and S. macrocarpus was composed of large cells;( 6) The mesophyll was differentiated into palisade parenchyma and spongy parenchyma,and the thickness of palisade parenchyma and spongy parenchyma and the ratio of palisade to spongy thickness are distinctly different among species. The palisade parenchyma of S. tonkinensis is differentiated into two layers;( 7) The main vein vascular tissues constitute a closed ring structure in S. macrocarpus and S. odoratissimus but an open semicircular structure in other species. The leaf epidermal micromorphology and anatomical structures can be used as an important basis for the identification and classification between species of Styrax,which is of some taxonomic significance.

Morphological characteristics, distribution and taxonomic consideration of Chionanthus retusus Lindl. & Paxton in Korea

The morphological characteristics of Chionanthus retusus Lindl. & Paxton in Korea are reviewed in this study through the comparison with its previous records and a distribution map of this species is created using previous flora and voucher specimens. The leaf epidermal micromorphology and the petiole anatomy are also briefly described.

Studies on leaf epidermal micromorphology, wood element characters and phytochemical screening of three medicinal plants of Convolvulaceae

The scientific evaluation of ethnomedicinally important plants is now being done thoroughly covering various aspects of study like efficacy of the crude drugs, chemistry of active principles, different pharmacognostic parameters, etc. The use of micromorphology and anatomy is now a recognised tool in the field of plant systematics. Therefore, in this investigation the micromorphology of leaf epidermis, stem xylem element characters and phytochemical screening of three ethnomedicinally important members of the family Convolvulaceae namely Evolvulus alsinoides, Evolvulus nummularius and Ipomoea cairica have been studied. The epidermal cells are found to be irregular in shape and the outlines of the cells are wavy in every species. Stomata are amphistomatic and mainly of paracytic type except in Evolvulus nummularius. Trichomes are glandular and non-glandular, unicellular or multicellular, straight or curved. The range of stomatal index varies from 11.40 to 20.00. Palisade ratio ranges from 6.2 to 9.8. The vessel element length ranges from 60.71 um to 357.10 um and the diameter varies from 21.78 um to 66.06 um. Perforation plate is simple and transverse or obliquely placed. Fibres are typical libriform, very long and diameter ranges from 10.71 um to 16.78 um. In every case, tracheids are long with spiral to condensed spiral type of sidewall thickening and diameter is from 07.14 um to 16.07 um. The active compounds are identified by the chemical colour reaction tests belonging to the phytochemical groups of amino acids, alkaloids, reducing sugars, flavonoids, saponins, steroids and triterpenoids, tannins, etc. The findings will be a useful marker for identification of the crude drugs obtained from the selected taxa. The purpose of the study is to know the leaf epidermal micromorphology, wood element characters and phytochemical screening of three ethnomedicinally important plants of the family Convolvulaceae as it has not been properly worked out. These micromorphological features and phytochemical screening will be very helpful in proper identification of respective crude drugs obtained from these three members of Convolvulaceae and also be used in detection of drug adulterants. Thus, it will be a tool in maintaining the quality of the drug obtained from these three plant species.

The Trillium pusillum Michaux Complex (Trilliaceae): Analysis of Pollen and Leaf Epidermal Micromorphology

TIMMERMAN-ERSKINE, M., R. R. DUTE, AND R. S. BOYD (Department of Biological Sciences, Auburn University, AL 36849-5407). The Trillium pusillum Michaux complex (Trilliaceae): Analysis of pollen and leaf epidermal micromorphology. J. Torrey Bot. Soc. 129:175-186. 2002.-The T. pusillum complex consists of five or six southeastern morphogeographical taxa with a confused taxonomic history. Some authors have considered them as a single species, whereas others have split the complex into various combinations of species and varieties. Our study examined pollen and stomatal characteristics of these taxa for their utility as taxonomic characters. All T. pusillum varieties have pollen characterized by somewhat spherical and inaperturate grains with rounded granulate ornamentation. Stomatal complexes lacked subsidiary cells and were aperigenous and homostomatic. Although trends were identified in both pollen diameter and stomatal size and shape, these characters were not reliable variety-specific taxonomic characters. Only T. pusillum var. texanum exhibited both abaxial and adaxial stomata, a feature that consistently distinguished it from other putative varieties that we examined. We suggest that this complex be subdivided into two species, T. texanum Buckley and T. pusillum Michaux, based upon these stomatal distribution patterns.