Pedestal hairs of the ant Echinopla melanarctos (Hymenoptera, Formicidae): morphology and functional aspects

The South East Asian arboreal Formicine Echinopla melanarctos, as well as some other members of this genus possess a cuticular structure unique in ants, the pedestal hairs. In E. melanarctos, about 700 pedestal hairs are situated on the dorsal and lateral surfaces of the head, the alitrunk, the petiole and the gaster. They are arranged in a polygon-like figuration. On the summit of each of the up to 200-μm high pedestals, a single central hair inserts. This hair (up to 500-μm long) is innervated by a single bipolar mechanosensitive sensory cell. The lumen of each tube-like pedestal contains (1) epithelial cells (2) the sensory cell and the auxiliary cells of the central hair and (3) the long efferent ductules of up to ten isolated bicellular glandular units. Each glandular unit is composed of a secretory glandular cell and a duct cell, all of which are located at the base of a pedestal. The cytoplasm of a glandular cell contains a well-developed end apparatus and is characterised by stacks of smooth and granular endoplasmic reticulum, numerous polyribosomes, a lot of mitochondria and some up to 5-μm large secretory vesicles. The secretion of the gland cells is released on the apex of the pedestal wall via small pores. Approximately 30 μm below their summit, some pedestals possess additionally (up to six) mechanosensitive hairs that are arranged ray-like. We suppose that the pedestal hairs are important in nest-space protection and find that only in ants with high pedestals on the head (Echinopla melanarctos and Echinopla pallipes), the compound eyes are stalked thus overtopping the pedestals.     

冬凌草腺毛的形态学及组织化学研究

利用光学显微镜对药用植物冬凌草地上部分腺毛的形态、分布和组织化学进行了研究。结果表明:(1)冬凌草的叶表皮有3种形态显著不同的毛,即非腺毛、盾状腺毛和头状腺毛;盾状腺毛和头状腺毛均具1个基细胞、1个柄细胞和头部;成熟的盾状腺毛的头部一般由4个分泌细胞组成,而头状腺毛头部由2个分泌细胞组成。(2)组织化学鉴定结果显示:2种腺毛中均含有黄酮类成分,盾状腺毛中还含有单萜、倍半萜等萜类成分;冬凌草甲素可能只存在于盾状腺毛中,但需要更直接的证据证明。研究认为,高密度的盾状腺毛可以作为筛选冬凌草高甲素含量品种的一项重要依据。     

甘草腺毛的形态发生和组织化学研究

利用扫描电镜及薄切片技术对甘草的腺毛形态发生和发育过程进行了观察,并对腺毛发育过程中黄酮类成分积累进行了组织化学定位研究。结果表明：甘草腺毛为多细胞构成的盾状腺毛,有长柄和短柄2种类型;前者主要分布在花萼片上,而后者主要分布于叶片上。组化鉴定结果显示：腺毛中存在着黄酮类成分、其他亲脂类和非纤维素多糖类成分;在腺毛的发育过程中,黄酮类物质是随腺毛的发育成熟,在头部盘状结构的分泌细胞及角质层下腔中积累。研究结果对进一步探讨甘草叶中黄酮类成分的合成及其作用提供科学依据。     

Developmental Ultrastructure of Glandular Trichomes of <Emphasis Type="Italic">Rosmarinus officinalis</Emphasis>: Secretory Cavity and Secretory Vesicle Formation

Glandular trichomes in the leaf lamina of Rosmarinus officinalis L. were examined by scanning and transmission electron microscopy. The leaves were characterized by an abundance of two types of glandular trichomes—small capitate and large peltate glandular trichomes. In addition to the glandular trichomes, numerous non-glandular trichomes were present on the abaxial surface of the leaf. These trichomes mainly predominated on the midrib, whereas glandular trichomes occurred on non-vein areas. At the initial phase of secretory cavity formation, hyaline areas were abundant in periclinal walls of head cells, while they were not observed in the anticlinal walls. The hyaline areas gradually increased in size, fusing with other areas throughout the wall. Loose wall material adjacent to hyaline areas was released from the head cell walls and migrated into the secretory cavities. As the secretory cavities continued to enlarge, the new vesicles emerging into the secretory cavities from the walls of head cells became surrounded with the surface of a typical membrane. They developed a round shape, but the contours of the vesicle surfaces appeared polygonal when tightly packed inside a cavity. These vesicles varied in size; small vesicles often possessed electron-dense contents, while large vesicles contained electron-light contents.     

Ficus carica L. leaf anatomy: Trichomes and solid inclusions

Ficus carica L., a typical plant of the Mediterranean environment, presents leaves covered by an extensive indumentum, and a mesophyll full of solid inclusions. The morphology and ultrastructure of the trichomes, calcium carbonate cystoliths and silicified structures of leaves of F. carica cv Dottato were investigated with light, confocal, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. At the same time, histochemical reactions were also employed to analyse the indumentum composed by glandular and non-glandular trichomes by applying chemical reagents and fluorescence microscopy. Non-glandular and glandular trichomes, capitate, are described. Non-glandular trichomes are unicellular simple, spine-like and present different morphology and sizes. The capitate glandular trichomes are present on leaf adaxial and abaxial surface and consist of one-celled stalk and 3/4 cells spherical head. Histochemical characterisation of leaf hairs revealed the presence of flavonoids, while glandular trichome head cells showed a complex mixture of alkaloids, essential oil and flavonoids. Cu and Al were found in the constitutive structures, spike and dome, of the cystoliths. Several epidermal cells and non-glandular trichomes were silicified. Leaf hairs, trichomes secretions, solid inclusions and silicification of F. carica leaf have significant roles to play in relation to leaf protection from external factors, including high-intensity radiation, herbivores or pathogens.     

Glandular trichomes of Ceratotheca triloba (Pedaliaceae): morphology, histochemistry and ultrastructure

This study was initiated to characterize the distribution, morphology, secretion mode, histochemistry and ultrastructure of the glandular trichomes of Ceratotheca triloba using light and electron microscopy. Its leaves bear two morphologically distinct glandular trichomes. The first type has long trichome with 8-12 basal cells of pedestal, 3-14 stalk cells, a neck cell and a head of four cells in one layer. The second type has short trichome comprising one or two basal epidermal cells, a unicellular or bicellular stalk and a multicellular head of two to eight cells. There is a marked circular area in the upper part of each head cell of the long trichome. This area is provided with micropores to exudate directly the secretory product onto the leaf surface by an eccrine pathway. The secretory product has copious amount of dark microbodies arising from plastids which are positive to Sudan tests and osmium tetroxide for unsaturated lipids. The secretion mode of short trichomes is granulocrine and involves two morphologically and histochemically distinct vesicle types: small Golgi-derived vesicles which are positive to Ruthenium Red test for mucilaginous polysaccharides; the second type is dark large microbodies similar to that of long trichomes with low quantity. These two types are stored in numerous peripheral vacuoles and discharge their contents accompanied by the formation of irregular invaginations of the plasmalemma inside the vacuoles via reverse pinocytosis. These two secretion modes of long and short trichomes are reported for the first time in the family Pedaliaceae. The long trichomes have more unsaturated lipids, while the short trichomes contain more mucilaginous polysaccharides.     

龙葵腺毛发育的细胞学研究

利用光学显微镜、扫描电镜和透射电镜技术,观察了龙葵“四叶一心”期时叶片及茎表皮的腺毛的种类、分布,探究了不同类型腺毛的起源、生长、成熟、分泌、衰老等发育过程的细胞学特征;通过组织化学染色和荧光显微技术,观察了龙葵腺毛成分、分布,为龙葵的进一步开发利用提供参考。结果表明：（1）龙葵腺毛分为单细胞头腺毛和多细胞头腺毛两类,前者主要分布于茎表面和叶上下表皮,后者主要分布于茎表面的单细胞头腺毛之间、叶脉及叶边缘;（2）龙葵腺毛发育起始于表皮细胞突起,单细胞头腺毛行顶端生长,具1-4个柄细胞,四种类型;多细胞头腺毛可再分为一层、两层与三层多细胞头腺毛,另具三种特殊类型;（3）龙葵成熟腺毛具分泌能力,通过皮下空间的物质积累导致腺毛头细胞表面形成突起、包块、破口,最终释放分泌物;而头细胞与柄细胞随即皱缩、衰老。（4）超微结构显示,腺毛头细胞中内质网与高尔基体极为丰富,合成代谢及分泌活动活跃,产生大量包裹嗜锇物质的囊泡,囊泡与细胞壁融合,进而将嗜锇物质转移至细胞壁并积累,随后储存在角质层下的皮下空间直至分泌释放;（5）组织化学染色结果表明,腺毛含有萜类、生物碱、脂类、蛋白质、酚类和多糖。头细胞中主要含有萜类、生物碱、脂类、蛋白质、酚类和中性多糖;柄细胞中主要含有萜类、生物碱、脂类。     

The extrafloral nectaries of cowpea (Vigna unguiculata (L.) Walp): I. Morphology,anatomy and fine structure

The cowpea bears two distinctive types of extrafloral nectaries. One, on the stipels of trifoliolate leaves, consists of a loosely demarcated abaxial area (1–2 mm diameter) of widely-spaced trichomes (papillae) borne on a stomata-free epidermis, and lacking a specific vascular supply. Each trichome has up to eight apical (head) cells, two to four intermediate cells, and a single large stalk cell. The secretory faces of the apical cells bear wall ingrowths and an easily detached cuticle. The wall separating the stalk cell and the underlying epidermal cell(s) has a mean plamodesmatal frequency of 25/m². The second type of nectary consists of a large elliptical mound of tissue (short and long axes about 2 mm and 4 mm) formed between a pair of flowers on an inflorescence stalk. It comprises four to eight cone-shaped subnits of secretory tissue, each with a circular secretory orifice and an individual supply of phloem, but not of xylem. Cells of the secretory tissue of the nectary subunits separate as they mature, and nectar flows to the orifice through the resulting intercellular spaces. Intact secretory cells and cellular debris are extruded into the nectar. Some of the sieve elements terminating in the inner secretory tissue exhibit open sieve pores. Each mature secretory cell contains many small (2 m diameter) spherical protein bodies and one to three large (up to 2–3 m diameter 15 m long), paracrystalline bodies. These inclusions are absent or not fully developed in inner, less mature regions of the secretory tissue. Mechanisms of secretion are proposed for the two classes of nectary, including estimates of flux of sugar into the trichomes of the stipel nectary.     

Foliar secretory trichomes of Ocimum obovatum (Lamiaceae): micromorphological structure and histochemistry

This study characterises the micromorphology, ultrastructure and main chemical constituents of the foliar glandular trichomes of Ocimum obovatum using light and electron microscopy and a variety of histochemical tests. Two types of glandular trichomes occur on the leaves: large peltate and small capitate. The head of each peltate trichome is made up of four broad head cells in one layer. The head of each capitate trichome is composed of two broad head cells in one layer (type I) or a single oval head cell (type II, rare). In peltate heads, secretory materials are gradually transported to the subcuticular space via fracture in the four sutures at the connecting walls of the head cells. Release to the head periphery occurs through opposite fracture in the four sutures in the head cuticle. In type I capitate trichomes, release of the secretions to the subcuticular space occurs via a pore between the two head cells, and release to the head periphery occurs through the opposite pore in the head cuticle. In type II capitate trichomes, the secreted material is released from the head cell through a ruptured particular squared area at the central part of the head cuticle. These secretion modes are reported for the first time in the family Lamiaceae. Histochemical tests showed that the secretory materials in the glandular trichomes are mainly essential oils, lipophilic substances and polysaccharides. Large peltate trichomes contain a large quantity of these substances than the small capitate trichomes. Ultrastructural evidence suggests that the plastids produce numerous lipid droplets, and the numerous polysaccharide small vesicles are derived from Golgi bodies.     

线纹香茶菜叶上腺毛发育的细胞学研究

为进行中药溪黄草基原植物的品种鉴定,采用光镜和电镜对线纹香茶菜(原变种)[Isodon lophanthoides var.lophanthoides]叶上腺毛的发育进行细胞学研究。结果表明,线纹香茶菜具有头状腺毛和盾状腺毛2种类型。头状腺毛无色透明,由1个基细胞、1个柄细胞和1或2个头部分泌细胞构成;盾状腺毛为红色,由1或2个基细胞、1个柄细胞和4~8个分泌细胞构成头部。2种腺毛均由原表皮细胞经两次平周分裂形成,后因柄细胞和头部细胞所处的分化状态不同而形成两类腺毛。2种腺毛超微结构表明,质体、高尔基体和粗面内质网为主要分泌物产生和运输的细胞器。当盾状腺毛成熟时,角质层下间隙充满了分泌物,其分泌物的性质很可能决定了线纹香茶菜腺毛的颜色。     

Glandular Trichomes in Satureja thymbra Leaves

The leaves of the aromatic plant Satureja thymbra have numerousglandular trichomes of two morphologically distinct types glandularhairs and glandular scales Investigations of the anatomy ofthese glandular trichomes with serial thick sections revealedthat the glandular hairs consist of three cells a foot, stalkand head cell Glandular scales also have a unicellular footand stalk Their heads, however, are composed of 12 cells Fourof these cells are small, occupying the central region of thehead, whereas the remainder are large and peripherally arrangedMorphometric analysis showed that, in leaf surface view, glandularscales are about 17-fold larger than glandular hairs In addition,glandular scales were found to occupy 5 7 % of the entire leafsurface area In each glandular scale the total amount of essentialoil, contained within both the subcuticular space and the interiorof the secretory cells, was calculated to be 2 51 x 10^–4mm³ The volume of the essential oil produced by all glandularscales on a single mature leaf was correspondingly determinedto be 0.059 mm³ Finally, the theoretical essential oil yieldof 100 g dry leaves of S thymbra was estimated to be 3 54 %(secretory activity of glandular scales only) Satureja thymbra, glandular trichomes, morphology, morphometry     

Glandular trichomes of Humulus lupulus var. Brewer's Gold: Ontogeny and histochemical characterization of the secretion

Leaves of Humulus lupulus possess two types of glandular trichomes: - peltate (lupulin) and bulbous.
Peltate trichomes are formed from a protodermal cell by two anticlinal divisions in perpendicular planes, followed by two periclinal ones that give rise to the initials of the head cells, the basal and the stalk cells. Head cells divide successively in radial and irregular planes. Fully developed peltate trichomes are built of a glandular head consisting of 30 to 72 cells, four stalk cells and four basal cells.
Bulbous trichomes are also formed from a protodermal cell by an anticlinal division followed by two periclinal ones that produce the initials of the glandular head cells, and the basal and stalk cells. Fully developed bulbous trichomes consist of four (occasionally eight) head glandular cells, two stalk cells and two basal cells.
The density of peltate trichomes decreases with the expansion of the leaves.
Both peltate and bulbous trichomes secrete essential oils. Peltate trichomes are the preferential site for the synthesis of bitter resins. Tannic acids could not be detected histochemically either in peltate or in bulbous trichomes. Both types of trichomes produce secretion that accumulates in the subcuticular space, being released, in the case of bulbous trichomes, by rupture of the cuticle.     

Leaf glandular trichomes in Empetrum nigrum: morphology,histochemistry, ultrastructure and secondary metabolites

The morphology, histochemistry and ultrastructure of the glandular trichomes on Empetrumnigrum leaves have been studied and more than a third of the metabolites were identified. Samples of the leaves were fixed and processed for light and electron microscopy. Glandular trichomes are situated on the inner surface of the rolled leaves. They have a clavate head and a short stalk. Histochemical tests and fluorescent microscopy demonstrate differentiated staining of the various cell types in the glandular trichome for proteins, pectins, lipids, tannins and phenylpropanoids. During secretion, the secretory cells contain rough and smooth endoplasmic reticulum, Golgi stacks with large vesicles, diversiform leucoplasts in contact with a reticular sheath and opaque deposits in the vacuoles. There are ultrastructural and functional differences between the secretory cells in the trichome head: synthesis of hydrophilic substances predominately occurs in the upper and middle secretory cells, whereas synthesis of lipophilic compounds takes place in the middle and lower secretory cells. Gas chromatography–mass spectrometry was used to determine the content of metabolites in the methanol extracts from the leaves. Many phenolic compounds (phenolic acids, bibenzyls, catechins, flavanones and flavan‐3‐ols) as well as several terpenoids were found. Two chalcones (2′,4′‐dimethoxydihydrochalcone and 2′,4′,6′‐trihydroxydihydrochalcone), one bibenzyl (batatasin III), one flavanone (7‐hydroxyflavanone) and 8 terpenoids (including phytol, α‐tocopherol, ß‐sitosterol, α‐amyrin, uvaol, oleanolic acid, ursolic acid and dehydroursolic acid) were identified in E. nigrum leaf extracts. The total yield of phenolic compounds is five to six times higher than the yield of terpenoids. It has been established that chalcones have no hydroxyl groups in ring B whereas bibenzyls have a hydroxyl group in the 3‐position in ring B. On the basis of the histochemistry, fluorescent microscopy, ultrastructure and chemical analysis, it may be concluded that synthesis and accumulation of phenolic substances and terpenoids takes place in the clavate glandular trichomes. Secondary metabolites synthesized in the trichomes protect leaf tissues from viruses, bacteria and pathogenic fungi.     

Light, conventional and environmental scanning electron microscopy of the trichomes of Cucurbita pepo subsp. pepo var. styriaca and histochemistry of glandular secretory products

BACKGROUND AND AIMS: In the present study, the differences between glandular and non-glandular trichomes, the secretory process and the method of secretion were studied. Previous studies on leaves of Styrian oil pumpkin (Cucurbia pepo var. styriaca) plants have shown that four morphologically and ontogenetically independent glandular and non-glandular trichome types and one bristle hair type can be distinguished. The four types of trichomes can be categorized into three glandular trichome types: type I, a short-stalked trichome with four head cells including a 'middle-cell', two stalk cells and one basal cell; type II, a long-stalked trichome with two head cells, a 'neck-cell' region and a long stalk area; type IV, a 'stipitate-capitate' trichome with a mesophyll cell basement, a short stalk and a multicellular head; type III, a non-glandular 'columnar-digit' trichome, which consists of two head cells continuous with three-celled stalk, and the basal cell. METHODS: The histochemical studies (the main classes of metabolite in secreted material of glandular trichomes) were conducted in fresh and fixed hand sections, using the following tests: Sudan black B, Nile blue A, osmium tetroxide, neutral red, Naturstoffreagent A, FSA (fuchsin-safranin-astra blue), NADI (naphthol + dimethylparaphenylenediamine) and ruthenium red. Each suggested differences in the intercalations during the ontogenetical development of each trichome during the development stage. KEY RESULTS: The histochemical reactions revealed the main components of the materials secreted by all types of trichomes, which include lipids, flavones and terpenes and the different cell wall compositions. Glandular secretions were observed during environmental scanning electron microscopy (ESEM) and the trichomes compared with those seen by conventional scanning electron microscopy (CSEM). CONCLUSIONS: Scanning electron microscopy and histochemical analysis demonstrated that each of the trichomes studied produced and released secretory products in a characteristic way.     

Development, oil storage and dehiscence of peltate trichomes in Thymus vulgaris (Lamiaceae)

The development, oil storage and dehiscence mechanism of the peltate oil–producing trichome in Thymus vulgaris L. was studied by conventional, fluorescence and electron scanning microscopy. A single epidermal initial forms the glandular trichome whose primordium becomes distinguishable from non–glandular trichomes at its 3–celled stage. The further divisions determine the formation of three functional compartments, (a) a basal reservoir cell, (b) an "endodermal" cell, and (c) a group of secretory head cells. At first, the gland head shows a bowl–like shape with a folded cuticular covering that raises successively assuming a dome–like form. During the differentiation of the gland cells, histochemical tests reveal the occurrence of a precise sequence of metabolic events: synthesis of RNA, proteins, glycoproteins, polysaccharides and, finally osmiophilic substances. At maturity, the cuticular sheath is formed by a non–cellulosic polysaccharide framework on which the cuticle is deposed. Proceeding towards the senescence, the polysaccharide framework disappears and a large crescent shaped pore forms, whereby essential oils are released. Collected results are discussed in order to interpret gland function and essential oil production.     

Distribution and morphology of the ampullary organs of the estuarine long-tailed catfish, <Emphasis Type="Italic">Euristhmus lepturus</Emphasis> (Plotosidae,Siluriformes)

Ampullary organs of Euristhmus lepturus occur in high densities along the head and in four parallel pathways along the trunk of the body. Large ampullary pores (125–130 μm) are easily distinguishable from other sensory epithelial pores due to the differences in size and the presence of a collar-like structure. Simple, singular ampullary organs of the head region consist of an ampullary pore connected to a long canal with a diameter of 115–175 μm before terminating as a simple ampulla with an external diameter of 390–480 μm. The ampullary canal is composed of 1–2 layers of flattened squamous epithelial cells, the basement membrane and an interlocking collagen sheath. The innermost cells lining the canal wall are adjoined via tight junctions and numerous desmosomes, as are those of the receptor and supportive cells. Canal wall tissue gives rise to a sensory epithelium containing between 242 and 285 total receptor cells, with an average diameter of 11.7 ± 5.3 μm, intermixed with medially nucleated supportive cells. Each receptor cell (21.38 ± 4.41 μm, height) has an apically positioned nucleus and a luminal surface covered with numerous microvilli. Neural terminals abut the basal region of receptor cells opposite multiple presynaptic bodies and dense mitochondria. Supportive cells extend from the ampullary lumen to the basement membrane, which is adjacent to the complex system of collagen fibres.     

Glandular Trichomes on Vegetative and Reproductive Organs of Leonotis leonurus (Lamiaceae)

The types of glandular trichomes, their ontogeny and patternof distribution on the vegetative and reproductive organs ofLeonotis leonurus at different stages of development, are studiedby light and scanning electron microscopy. Two morphologicallydistinct types of glandular trichomes (peltate and capitate)are described. Peltate trichomes, at the time of secretion,are characterized by a short stalk, which is connected witha large spherical head composed of eight cells in a single layer.Capitate trichomes can be divided into various types. Generally,they consist of a four-celled head supported by one or threestalk cells. The two kinds of trichomes differ in the secretionprocess. In the peltate trichomes, the secretory product seemsto remain accumulated in a subcuticular space, unless an externalfactor damages it. In the capitate trichomes, this product probablybecomes released through micropores. On the leaves peltate andcapitate trichomes are abundant, while on the flowers only thepeltate trichomes are numerous and the capitate are rare orabsent.Copyright 1995, 1999 Academic Press Leonotis leonurus R. Br., lion's ear, lion's tail, Lamiaceæ, glandular trichomes, morphology, ontogeny     

地黄叶和茎的解剖学及组织化学研究

采用解剖学和组织化学方法对地黄叶和茎的显微结构以及梓醇、多糖的分布进行观察研究,以明确梓醇和多糖在地黄叶和茎中的分布特征。结果显示:(1)地黄叶的上、下表皮均分布有腺毛和非腺毛,腺毛都属于头状腺毛,包括长柄和短柄的头状腺毛,两类腺毛的分泌物化学成分主要是黄酮和多糖;叶的上、下表皮上都分布有无规则型气孔,下表皮的气孔密度比上表皮的大,但气孔指数相差不大;栅栏组织由2～3层薄壁细胞构成,排列紧密,海绵组织薄壁细胞形状无规则,细胞间隙大。(2)组织化学研究表明,海绵组织中黄斑样的薄壁细胞是梓醇和多糖的贮存场所,这类薄壁细胞在叶片边缘的齿末端处最为集中,茎的皮层、韧皮部和木质部的薄壁细胞也都是梓醇和多糖的贮存场所。     

Phylloplanins of tobacco are defensive proteins deployed on aerial surfaces by short glandular trichomes

In plants, defensive proteins secreted to leaf aerial surfaces have not previously been considered to be a strategy of pathogen resistance, and the general occurrence of leaf surface proteins is not generally recognized. We found that leaf water washes (LWW) of the experimental plant Nicotiana tabacum tobacco introduction (TI) 1068 contained highly hydrophobic, basic proteins that inhibited spore germination and leaf infection by the oomycete pathogen Peronospora tabacina. We termed these surface-localized proteins tobacco phylloplanins, and we isolated the novel gene T-Phylloplanin (for Tobacco Phylloplanin) and its promoter from N. tabacum. Escherichia coli-expressed T-phylloplanin inhibited P. tabacina spore germination and greatly reduced leaf infection. The T-phylloplanin promoter, when fused to the reporter genes beta-glucuronidase and green fluorescent protein, directed biosynthesis only in apical-tip cell clusters of short, procumbent glandular trichomes. Here, we provide evidence for a protein-based surface defense system in the plant kingdom, wherein protein biosynthesis in short, procumbent glandular trichomes allows surface secretion and deposition of defensive phylloplanins on aerial surfaces as a first-point-of-contact deterrent to pathogen establishment. As yet uncharacterized surface proteins have been detected on most plant species examined.     

Trichome micromorphology in Turkish species of Ziziphora (Lamiaceae)

Ziziphora L. is represented by 5 species and 2 subspecies in the flora of Turkey: Z. clinopodioides, Z. capitata, Z. persica, Z. tenuior, Z. taurica subsp. taurica, Z. taurica subsp. cleonioides. It is difficult to distinguish between some Ziziphora taxa because of their morphological similarities. In this study, the leaf and calyx trichomes of Ziziphora taxa in Turkey were studied in order to assess anatomical variations that may serve as distinguishing characters. Their micromorphological features were surveyed by scanning electron microscopy (SEM) and light microscopy (LM). Trichomes on leaves and calyx can be divided into two general types: non‐glandular trichomes and glandular (secretory) trichomes. The non‐ glandular trichomes are simple, acicular or curved with cuticular micropapillae. They usually consist of one or more additional cells. The glandular trichomes are divided into two types: peltate and capitate and Ziziphora taxa can easily be distinguished by presence/absence, density and types of glandular trichomes on leaves and calyx. The peltate trichomes consist of 12 or 18 secretory head cells in a single disc; four or six central cells surrounded by eight or twelve peripheral ones. Peltate trichomes are absent on the adaxial leaf surface of Z. capitata and Z. persica. Two types of capitate trichomes are present in Ziziphora. The capitate trichomes are only absent on the calyx surface of Z. persica. In addition, the trichome micromorphology provides some support for separating the two subspecies of Z. taurica. In conclusion, Ziziphora taxa can easily be distinguished by cell number, cell shape presence/absence and density of the glandular trichomes on leaves and calyx.