Glandular Ones Research Articles

An Integrative Approach to Selected Species of Tanacetum L. (Asteraceae): Insights into Morphology and Phytochemistry.

In this work, we studied Tanacetum vulgare, Tanacetum parthenium, and Tanacetum corymbosum (Asteraceae) cultivated at the Ghirardi Botanic Garden (Toscolano Maderno, Brescia, Northern Italy) of the University of Milan. An integrative research approach was adopted: microscopic and histochemical, with special focus on the secretory structures responsible for the productivity of secondary metabolites; phytochemical, with the analysis of the essential oil (EO) profiles from the air-dried, flowered aerial parts collected in June 2021; bio-ecological, with emphasis, based on literature data, on the ecology and biological activity of the main EO components. In all three species, two basic trichome morphotypes (flagellar non-glandular and biseriate glandular) occurred with different distribution patterns. The glandular ones produced terpenes, along with flavonoids. A high level of chemical variability in the EO compositions emerged, specifically for qualitative data. T. vulgare profile was more complex and heterogeneous than those obtained from T. parthenium and T. corymbosum, with camphor as the predominant compound, followed by farnesol and α-santalone, respectively. Finally, the obtained scientific findings were made available to the visitors of the botanic garden through new dissemination labeling that highlights the "invisible", microscopic features of the plants, from an Open Science perspective ("Botanic Garden, factories of molecules…work in progress"-Lombardy Region Project Lr. 25/2016, year 2021).

Trichomes Morphological Diversity in Some Species from Related Tribes of Asteraceae Family in Iraq

This study includedepidermal appendages characters of ten species belongingto the familyAsteraceae.Most of the studied species are characterized by eglandular, glandular, trichomesand papillae which are variable according to itskind, number of cells, shape, dimensions, characteristicsof surrounding cells, wall thickness and the position. Results showed that all species included glandular and eglandulartrichomes exceptCosmos bipinnatus, Ecliptaprostrate, andEupatoriumcannabinum that lacked in glandular trichomes and were based on their specific details.Trichomes were divided into different groups. The glandular ones involved sessile glandular or group multicellular and the head wasmace-shaped or rounded.Whereaseglandulartrichomes are classified into various groups,unicellular trichomes group with obtuse or acute apex or with tuft shape or dendroid, dicellular.Trichome group uniserriate or biserriate, and multicellular trichome group which is widely different in their shapes, dimensions, number of cell and the position. Papillae distributed on stem, corolla, and stigma have triangular-shape with acute apex or finger-like shape with obtuse apex.Hence,trichomes reveal a taxonomic importance in species identification and determine the relationships among them in their tribes.

Invasion of Eragrostis albensis in Central Europe: distribution patterns, taxonomy and phylogenetic insight into the Eragrostis pilosa complex

The Eragrostis pilosa complex (Poaceae) comprises five widely distributed and regionally invasive species—E. albensis, E. amurensis, E. imberbis, E. multicaulis, and E. pilosa, distinguished by tiny and variable morphological characters and with so far unknown phylogenetic relationships. Recently, some doubts have been raised about the status of an invasive glandular morphotype occurring in Central Europe assigned either to E. amurensis or to E. albensis. Here, we addressed this issue by analysing morphology, internal transcribed spacers of nuclear ribosomal DNA, and five inter-simple sequence repeat markers. The genetic evidence supported closer relationship of this glandular morphotype to eglandular E. albensis, widely established in Central Europe, than to glandular E. amurensis described from Asia. We propose to adopt a new taxonomic treatment that E. albensis includes both eglandular and glandular individuals, and to classify the glandular ones as E. albensis var. scholziana M. Nobis & A. Wróbel var. nova. Currently this new taxon is known from a dozen of localities in Central Europe and is invasive in the lower section of the Oder River valley, whereas Eragrostis albensis var. albensis has already spread widely across Europe in riparian phytocenoses and anthropogenic habitats. Since probably the first registered records in 1940s, it has been observed in European part of Russia, Belarus, Ukraine, Poland, Slovakia, Czech Republic, Germany, Austria, the Netherlands, and its further invasion is likely to proceed. We provided distribution maps concerning spread dynamics of E. albensis in Europe from 1947 to 2020. In total, the species has been observed on over 1300 localities so far, most of which were found after 2000.

Анатомическое строение листовой пластинки у некоторых представителей родов Comarum, Dasiphora и Potentilla (Rosaceae), произрастающих в Приамурье

The structure of leaf blades was studied in nine species of the genus Potentilla s. l., as well as in two species representing the genera Comarum L. and Dasiphora Rafin., close to Potentilla collected in the Priamurye. In all studied species they are fairly monotonous in structure and have a dorsiventral mesophyll. Most species have hypostomata leaves. P. paradoxa Nutt. ex Torr. et Gray has an amphistomatic leaf type. Anomocyte type of stomata was revealed in all studied species. Differences in the structure of leaf blades in the species are expressed mainly in the size and shape of the cells of the upper and lower epidermis (the shape of the anticlinal walls of the cells of the upper and lower epidermis), in the leaflet. The cells of the upper epidermis are larger than the cells of the lower epidermis, mostly with straight, sometimes tortuous or strongly tortuous anticlinal walls. Cells of the lower epidermis with weakly sinuous, sinuous and strongly tortuous anticlinal walls. Leaves on the upper side of the leaf in most species are covered with simple covering hairs, rarely there is no pubescence. On the underside, the leaves are mostly covered with simple hairs covering them, and glandular ones are also found. Leaf scarring with glandular and covering hairs,with the exception of P. sawiczii Schischk. et Kom., in conjunction with the shape of the leaf blade, is a sectional feature to delineate sections of one subgenus Hypargyrium. The sign of absence of pronounced protrusion from the underside of the leaf that forms the central vein in the representatives of the subgenus Schistophyllidium (P. bifurca L., P. semiglabra Juz.), could be successfully used in the taxonomy of the genus Potentilla at subgenus level.&nbsp

The tomato B-type cyclin gene, SlCycB2, plays key roles in reproductive organ development, trichome initiation, terpenoids biosynthesis and Prodenia litura defense

Cyclins exist extensively in various plant species. Among them, B-type cyclins play important roles in the transition of G2-to-M. However, few B-type cyclins have been reported to participate in reproductive organ development and trichome formation. In this study, transgene analysis showed that SlCycB2 overexpression caused abnormal flower with the unclosed stamen, shortened style and aberrant pollen. In addition, nearly all non-glandular trichomes, as well as the glandular ones were disappeared. On the contrary, suppression of SlCycB2 could promote type III and type V trichomes formation. Detection of secondary metabolites indicated that the production of monoterpene and sesquiterpene were significantly decreased in SlCycB2-OE plants, which thus resulted in the reduction of the defense against Prodenia litura. Transcriptome profile demonstrated that the differentially expressed genes mainly participate in the biosynthesis of terpenes, cutin, suberine and wax. Furthermore, we identified several homologs of SlCycB2, SlCycB3, NtCycB2, AtCycB2, which have similar regulatory functions in trichome formation. These results indicate that SlCycB2 plays a critical role in reproductive organ development, multicellular trichome initiation, secondary metabolite biosynthesis and Prodenia litura defense in tomato. The similar roles of its homologs in multicellular trichome formation suggest that Solanaceous species may share common regulatory pathway.

Morphoanatomical and preliminary phytochemical studies of two specimens of Dorstenia Contrajerva native to Guatemala

This work presents a descriptive study of the morphoanatomical characters and preliminary phytochemical data, of the vegetative organs and the inflorescences of Dorstenia contrajerva L. and D. contrajerva var. tenuiloba (Blake) Standl. & Steyerm. that grows in Guatemala, useful to establish identity characters for quality control standards, especially when they are dry and/or fragmented. The techniques used were freehand cutting, leaf diaphanization, maceration and screening of secondary metabolites by histochemical and thin layer chromatography methods. Both specimens of D. contrajerva showed widely simple lobed leaves, actinodromous reticulate venation, hypostomatic leaves with anisocytic and anomocytic stomata at level and sunk. Glandular hairs with 1-2 cellular head and unicellular stalk, uncinate, large and small simple hairs. The stem and rhizome, circular and irregular, present simple uncinate hairs, laminar collenchyma and open collateral vascular bundles, arranged in a eustele. A polyarch root and evident cuticle was found. Inflorescence shows simple uncinate and hispidule large and small hairs, glandular ones with unicellular stalk and 1-2 cellular head and papillary hairs. The phytochemical screening showed the presence of starch grains, fats and oils, mucilages, saponins and coumarins. Most of the findings in this study, matches the ones reported for other authors to other species of Moraceae family, but many of them were no previously reported for other species of Dorstenia genus. Original photomicrographs show the main characters.

Comparative glycopattern analysis of mucins in the Brunner's glands of the guinea-pig and the house mouse (Rodentia)

The mucins secreted by the Brunner's glands and the duodenal goblet cells of the Guinea-pig and the house mouse were compared by conventional and FITC-conjugated lectin histochemistry. Methylation/saponification and sialidase digestion were performed prior to lectin binding to detect the residues subterminal to sulfated groups and sialic acid, respectively. In the Guinea-pig the Brunner's glands produce class-III stable sulfosialomucins. Sialic acid is mostly 2,6-linked to galactose or to N-acetylgalactosamine and is in part O-acetylated in C7, C8, and C9. Sulfated groups are probably linked to sialic acid and N-acetylgalactosamine. Terminal residuals of N-acetylglucosamine, galactose, N-acetylgalactosamine and fucose linked in α1,2, α1,3, and α1,4 are also present. Duodenal goblet cells of the Guinea-pig present a lower number of residuals in respect to the Brunner's glandular ones, with sialic acid and N-acetylgalactosamine subterminal to sulfated groups. In the house mouse the Brunner's glands produce class-III stable neutral mucins, binding to same lectins as in the Guinea-pig except for those specific to sialic acid. A diversity of fucosylated residuals higher than in the Guinea-pig is observed. The mouse duodenal goblet cells lack stable class-III mucins, have little sialic acid and present a lower number of residuals in respect to the correspondent Brunner's glands. Regulation of the acidic intestinal microenvironment, prevention of pathologies and hosting of microflora can explain the observed results and the differences observed between the two rodents.

Identity Characteristics of three Guatemalan Edible and Medicinal species

The diagnostic characteristics for the correct identification of Fernaldia pandurata, Cucurbita argyrosperma and Solanum nigrescens, popularly used as food and medicine, were established in the present study. The macroscopical and microscopical description, histochemical screening of secondary metabolites, organoleptical analysis of fresh and dry drug, acute toxicity, determination of total and acid ashes, and moisture percent for each species, were carried out. F. pandurata flowers, strongly aromatic and greenish-white in fresh plant material, become brown in the dry drug, which include some leaves and stem parts. Microscopically, large epidermal cells, evident cuticle, lacunar collenchyma, paracytic type stomata, and different varieties of hairs, appear. Non-glandular hairs show multicellular, verrucous, or acicular shape, and diversity of bases; glandular ones with unicellular blunt heads, and unicellular short stalks; sclereids, prismatic calcium oxalate crystals and pollen of circular shape with size ranges from 60-80 microns and pore-like opening were also found. C. argyrosperma seed with green color, microscopically exhibits reticulated cover and undulations; the leaves and stem, like other Cucurbitaceae members, show angular collenchyma, anomocytic type stomata, bicolateral vascular bounds surrounded by sclerenchyma, abundant non-glandular multicellular large and short elevated hairs, multicellular glandular ones with unicellular foot. S. nigrescens flowers are pale purple or white and exhibit a dark zone near de base; microscopically, leaves and stem shows non-glandular hairs, multicellular, verrucous with four and six cells in the base, plains and unicellular with blunt end with diversity of bases, glandular ones with unicellular foot and multicellular blunt heads and calcium oxalate druses. None of the species showed significant toxicity.

ANÁLISE MICROSCÓPICA FOLIAR DE MUTAMBA (Guazuma ulmifolia LAM., MALVACEAE)

Guazuma ulmifolia Lam. é uma planta arbórea, nativa das Américas e reposicionada atualmente na família Malvaceae. É conhecida comumente como mutamba ou chico-magro, e utilizada na medicinal popular como cicatrizante e no tratamento de distúrbios gastrointestinais e respiratórios. Estudos fitoquímicos indicaram a presença de taninos e flavonoides nos órgãos vegetativos aéreos. Ensaios farmacológicos comprovaram as atividades gastroprotetora e antibacteriana de extratos da planta. Ao analisar a anatomia foliar de G. ulmifolia, este trabalho buscou estabelecer os caracteres estruturais de fácil reconhecimento para a identificação microscópica dessa potencial droga vegetal. O material foi coletado de espécimes cultivados no Cerrado. Estudaram-se o terço inferior do limbo e o pecíolo de folhas adultas, por meio de observações feitas em microscopia fotônica e eletrônica de varredura. Testes microquímicos foram também conduzidos com reativos usuais. Em ambas as faces epidérmicas, ocorrem tricomas estelares e glandulares. Os primeiros são formados por tricomas tectores unicelulares, reunidos pela base. Os glandulares são capitados, apresentando um pedicelo curto e glândula ovoide. A cutícula é nitidamente estriada e os estômatos são anomocíticos e restritos à superfície abaxial. O mesofilo é dorsiventral e a nervura central tem secção biconvexa e é percorrida por um único feixe vascular em arco aberto, envolto sucessivamente por bainhas esclerenquimática e parenquimática, esta contendo compostos fenólicos. O pecíolo tem contorno circular e um ou mais feixes vasculares colaterais. Ocorrem células com conteúdo mucilaginoso e fenólico na folha, bem como cristais prismáticos de oxalato de cálcio.

Aberrant Cdx2 expression in endometrial lesions with squamous differentiation: important role of Cdx2 in squamous morula formation

Only a few reports have described Cdx2 expression in endometrial lesions of the uterus. Our aim was to determine whether Cdx2 expression is related to squamous differentiation in endometrial lesions. Furthermore, we examined whether there is any correlation between Cdx2 and beta-catenin, a well-known marker of aberrant nuclear accumulation in endometrial squamous foci secondary to mutation. We performed immunohistochemical analysis of 225 cases (29 normal endometrium, 28 nonproliferative conditions, 21 polyps, 46 hyperplasias, and 101 endometrioid carcinomas) that included 72 cases (4 polyps, 16 hyperplasias, and 52 carcinomas) showing morular or keratinizing squamous differentiation (SD(+)). Normal endometrium and nonproliferative conditions showed no staining for Cdx2. Whereas there was a low rate of Cdx2 positivity in SD(-) polyps (5.9%) and hyperplasias (10%), all SD(+) lesions expressed Cdx2 (P < .001). Thirty-eight (73%) of the SD(+) carcinomas were positive for Cdx2, whereas only 6 SD(-) cases (14.0%) were positive (P < .001). Furthermore, the larger the number of squamous foci, the greater the number of Cdx2-positive cells that was found. The labeling indices of Cdx2 were significantly higher in morular components than in keratinizing or glandular ones (P < .001). There was a strong correlation of the labeling indices of Cdx2 and beta-catenin in squamous foci of hyperplasias and carcinomas. Using immunofluorescence, we confirmed the coexpression of the 2 markers. The Cdx2 protein is expressed frequently in endometrial lesions with squamous differentiation, especially morular-type differentiation, and correlates strongly with nuclear beta-catenin expression. These facts suggest that Cdx2 plays an important role in squamous morula formation.

Estudo anatômico de folha e caule de Elephantopus mollis Kunth (Asteraceae)

Conhecida comumente como erva-de-colégio, erva-grossa e sussuaiá, Elephantopus mollis Kunth (Asteraceae) é uma espécie herbácea perene, de base sublenhosa, ramos curtos e flores arroxeadas. Suas folhas são empregadas como emoliente, resolutivo, sudorífico e no tratamento de bronquite, tosse e gripe na medicina popular. O objetivo deste trabalho foi estudar caracteres anatômicos foliares e caulinares, a fim de fornecer subsídios aplicáveis à identificação da planta medicinal. Folhas adultas e fragmentos de caules foram fixados, seccionados e corados com azul de astra/fucsina básica ou com azul de toluidina. Testes microquímicos e análise ultra-estrutural de superfície foram também executados. A folha possui epiderme uniestratificada, recoberta por cutícula estriada e, em vista frontal, tem células com contorno ondulado. Ocorrem tricomas tectores e glandulares. Os primeiros são eretos, pluricelulares e unisseriados. Os tricomas glandulares são capitados e bisseriados. O mesofilo é dorsiventral e a nervura central é percorrida por feixes vasculares colaterais dispostos em arco aberto. O caule, em estrutura secundária inicial, possui epiderme unisseriada com cutícula estriada e tricomas semelhantes aos da folha. No córtex, observam-se colênquima anelar alternado com clorênquima e endoderme com estrias de Caspary. Calotas esclerenquimáticas apõem-se ao floema. Este é formado pelo câmbio vascular em direção à periferia e o xilema é gerado de modo centrípeto. A medula é parenquimática. Pequenos cristais de oxalato de cálcio estão presentes na folha e no caule.

Smallanthus sonchifolius (Poepp.) H. Rob. (yacón): identificação microscópica de folha e caule para o controle de qualidade farmacognóstico

Yacon is the common name of the perennial herb native to the Andes, Smallanthus sonchifolius (Poepp. ) H. Rob. (Asteraceae), cultivated in different countries as food and medicinal resource. Fleshy roots and aerial vegetative organs are often used in the treatment of diabetes. This work has aimed to study the anatomical characters of the leaf and stem, aiming to supply information for microscopic identification of the pharmacognostic quality control. The botanical material was fixed and prepared according to standard techniques of light and scanning electron microscopy. The leaf is amphistomatic, predominantly with anomocytic stomata. Non-glandular and glandular trichomes are present, being the former multicellular and uniseriate. The glandular ones are short and multicellular, with two series of cells. The mesophyll is dorsiventral and the midrib has various collateral vascular bundles in centric arrangement. The young stem has remaining epidermis, angular collenchyma, cortical parenchyma, endodermis and continuous cylinders of phloem and xylem. Secretory ducts are found in the leaf and stem. The assembled characters, such as non-glandular and glandular trichomes as well as secretory ducts and endodermis with Casparian strips, are useful for the quality control of this species.

Stem and leaf anatomy of Plectranthus neochilus Schltr., Lamiaceae

Plectranthus neochilus Schltr. is an aromatic herb named boldo or boldo-gamba and employed for treating hepatic insufficiency and dyspepsia in folk medicine. This paper has investigated its stem and leaf anatomy, in order to contribute for the medicinal plant identification. The botanical material was prepared according to standard microtechniques. The stem has quadrangular transection and, in secondary growth at the level analyzed, shows uniseriate epidermis and numerous trichomes. The glandular ones are capitate and peltate. The former has short unicellular or long multicellular stalk and uni- or bicellular head. The latter presents short stalk and eight-celled ovoid head. The non-glandular trichomes are multicellular, uniseriate and coated with granular cuticle. It is observed angular collenchyma, cambia forming phloem outward and xylem inward, and perivascular fiber caps next to the phloem. The blade has uniseriate epidermis coated with striate cuticle, diacytic stomata on both surfaces, numerous trichomes similar to the stem ones, and homogeneous mesophyll. The midrib shows one or two collateral bundles and the petiole has many of them distributed as an open arc.

Induction of glandular and non-glandular trichomes by damage in leaves of Madia sativa under contrasting water regimes

Plant traits may play multiple functional roles simultaneously. Leaf trichomes have been related to resistance against herbivores as well as to enhanced water economy in the plant. In a greenhouse study, we evaluated the interactive effect of damage (control vs. mechanical damage) and water availability (control vs. low watering) on the expression of glandular and non-glandular leaf trichomes in the annual Chilean tarweed Madia sativa (Asteraceae). We found that the overall trichome density increased both after damage and when plants were grown under water shortage. Interestingly, the type of trichome induced after damage varied with each water environment. While damage induced glandular trichomes only under control watering, non-glandular trichomes were induced by damage only under experimental drought. Results indicate that in M. sativa glandular trichomes are equally induced by drought or damage but there is no additive effect of these factors. In both cases glandular trichome density apparently reached a limit, which may be interpreted in terms of constraint or efficacy. On the other hand, the synergistic effect of damage and drought on non-glandular trichomes might suggest that, compared to glandular ones, these trichomes are less responsive to each stress factor separately. Thus, for plants to induce non-glandular trichomes they must be subjected to a degree of stress above a threshold that was not reached for each individual factor in our experimental setting. We did not detect a significant correlation between trichome types. Thus, the contrasting patterns observed likely reflect independent responses of trichomes to the evaluated factors.

DIAGNOSE MORFOANATÔMICA DE AROEIRA (Schinus terebinthifolius RADDI, ANACARDIACEAE)

A família Anacardiaceae é de ocorrência pantropical e inclui espécies de importância alimentar, ornamental e medicinal. Schinus terebinthifolius Raddi, conhecido como aroeira, tem folhas e cascas de caule preparadas tradicionalmente na forma de decocto, com fins expectorante, anti-séptico, antidiarréico e cicatrizante. Com o objetivo de apresentar dados úteis à diagnose morfoanatômica, este trabalhou analisou os caracteres macro e microscópicos de folha e caule dessa planta medicinal. O material vegetal foi identificado, fixado, seccionado e corado de acordo com microtécnicas usuais. Análise ultra-estrutural de superfície foi também realizada. As folhas são alternas, compostas, imparipenadas, geralmente com nove ou onze folíolos. As células epidérmicas são poligonais e revestidas por cutícula estriada. Estômatos anomocíticos ocorrem na face abaxial. Tricomas tectores unicelulares e glandulares capitados pluricelulares, camada subepidérmica e mesofilo dorsiventral são observados. A nervura central, a raque e o pecíolo são semelhantes, sendo percorridos por vários feixes vasculares colaterais em arranjo cêntrico. Canais secretores estão associados ao sistema vascular. No caule, o felogênio tem instalação periférica. Notam-se células pétreas e fibras no córtex, cilindro floemático externo ao xilemático e canais secretores no floema e na medula. Idioblastos com cristais ocorrem na folha e no caule.

ANATOMICAL STUDIES ON SCOPOLIA CARNIOLICA JACQ. VEGETATIVE ORGANS

Scopolia carniolica Jacq. is a medicinal species of Solanaceae, harvested from the Romanian spontaneous flora for its atropine and scopolamine content. We have analyzed the anatomical structure of the vegetative organs (rhizome, root, stem and leaf) and the biometrical parameters of the leaf blade (vascular islet, stomatal index and palisade ratio), in order to establish the main specific characters and differential elements useful for the correct identification and for avoiding the impurification of medicinal products. The characteristic structures for the rhizome and root are the secondary ones, mainly with parenchyma elements and lacking in mechanical fibres; the stem has a primary becoming secondary structure, bicolateral vascular bundles with cambium in the interior and between them and endoderma as starch layer. The sand cells are characteristic for rhizome, root and stem structures. On the leaf surface were identified protector multicellular trichomes and specific secretory and glandular ones.

Attachment ability of the beetle Chrysolina fastuosa on various plant surfaces

AbstractTo study the role of different structures of a plant surface preventing insect attachment, a variety of plant surfaces were screened. Attachment ability of the beetle Chrysolina fastuosa Scop. (Coleoptera, Chrysomelidae) was measured on 99 surfaces among them smooth, hairy, felt‐like, waxy, and glandular ones of three plant organs (stems, leaves, fruits) of 83 plant species belonging to 45 families. Insects attached successfully to smooth, hairy, and felt‐like substrata. These surface types did not effect the further attachment of C. fastuosa, indicating the adhesive system remained intact after contacting these substrata. However, the beetles could not attach properly to surfaces covered with wax crystalloids or glandular hairs. In most experiments on pruinose plant substrata, no influence of the surfaces on the subsequent attachment ability of insects was observed. Only in one case (the stem of Acer negundo), was such an impairment recorded, but recovery of attachment ability was fast. Crystalloids of this plant species probably temporarily disable function of tenent setae of C. fastuosa. Four hypotheses, explaining anti‐adhesive properties of plant surfaces, covered with wax crystalloids are proposed. A plant surface with glandular trichomes disabled the attachment system of the beetle for a long time. Secretions of trichomes probably glue tenent setae together making further attachment impossible.

Morphology and distribution of trichomes in two endemic Teucrium species of Macaronesia

Summary The morphology and the distribution of the trichomes on the vegetative and reproductive organs of two endemic Teucrium species of Macaronesia (T. betonicum and T. heterophyllum) were studied by SEM. Both species possess an indumentum constituted by long, morphologically different non-glandu- lar trichomes and three types of glandular ones, differently distributed, depending on the organ studied. The particular distribution of the glandular trichomes on the inner surface of the corolla and on the anther filament seems to be of taxonomical importance.

The dense indumentum with its polyphenol content may replace the protective role of the epidermis in some young xeromorphic leaves

The bright, yellow-green, ammonia-induced fluorescence of polyphenol compounds contained in the nonglandular hairs and within the epidermis of Olea europaea and Quercus ilex leaves was age dependent. Epifluorescence microscopic examination of transverse sections of leaves from both species showed that abaxial and adaxial epidermal layers emitted the characteristic green-yellow bright fluorescence only in late developmental stages, when a considerable decrease of the trichome density had already occurred. At earlier developmental stages, only the dense and thick trichome layer emitted the bright green-yellow fluorescence. In addition, the trichomes of young leaves of Olea and Quercus resembled the glandular ones of other species morphologically and possibly functionally. These findings suggest that the protective role of the trichome against ultraviolet-B radiation damage and (or) other environmental factors is particularly significant during the early stages of leaf development and may be less important at later stages, when the protective role is taken over by the epidermis. Keywords: leaf hairs, phenolics, UV-B radiation damage, leaf development, Olea europaea L., Quercus ilex L.

Glandular trichomes and sesquiterpene lactones of Artemisia nova (Asteraceae)

Abstract The leaves of Artemisia nova Nelson are covered with a dense layer of nonglandular trichomes that obstruct the observation of glandular trichomes on the leaf surfaces. An acid-staining technique was developed that eliminates interference from the nonglandular trichomes and stains the glandular ones red, allowing them to be seen under a light microscope. Using this method it was found that these glands develop on both leaf surfaces, except over veins, and cover 21–35% of the leaf surface area at densities of 50–70 per mm 2 . Mature glands are sac-like structure with a thin sheath or cuticle surrounding a clear transparent fluid. This fluid contains all of the sesquiterpene lactones present in the leaves, and some of the monoterpenes. These terpenoids were responsible for the red color of the glands after acid treatment.