Nectariferous Tissue Research Articles

Is nectar reabsorption restricted by the stalk cells of floral and extrafloral nectary trichomes?

Reabsorption is a phase of nectar dynamics that occurs concurrently with secretion; it has been described in floral nectaries that exude nectar through stomata or unicellular trichomes, but has not yet been recorded in extrafloral glands. Apparently, nectar reabsorption does not occur in multicellular secretory trichomes (MST) due to the presence of lipophilic impregnations - which resemble Casparian strips - in the anticlinal walls of the stalk cells. It has been assumed that these impregnations restrict solute movement within MST to occur unidirectionally and exclusively by the symplast, thereby preventing nectar reflux toward the underlying nectary tissues. We hypothesised that reabsorption is absent in nectaries possessing MST. The fluorochrome lucifer yellow (LYCH) was applied to standing nectar of two floral and extrafloral glands of distantly related species, and then emission spectra from nectary sections were systematically analysed using confocal microscopy. Passive uptake of LYCH via the stalk cells to the nectary tissues occurred in all MST examined. Moreover, we present evidence of nectar reabsorption in extrafloral nectaries, demonstrating that LYCH passed the stalk cells of MST, although it did not reach the deepest nectary tissues. Identical (control) experiments performed with neutral red (NR) demonstrated no uptake of this stain by actively secreting MST, whereas diffusion of NR did occur in plasmolysed MST of floral nectaries at the post-secretory phase, indicating that nectar reabsorption by MST is governed by stalk cell physiology. Interestingly, non-secretory trichomes failed to reabsorb nectar. The role of various nectary components is discussed in relation to the control of nectar reabsorption by secretory trichomes.

The systematic significance of floral morphology, nectaries, and nectar concentration in epiphytic cacti of tribes Hylocereeae and Rhipsalideae (Cactaceae)

A long-standing interest in cactus taxonomy has existed since the Linnaean generation, but an appreciation of the reproductive biology of cacti started early in the 1900s. Numerous studies indicate that plant reproductive traits provide valuable systematic information. Despite the extensive reproductive versatility and specializations in breeding systems coupled with the striking floral shapes, the reproductive biology of the Cactaceae has been investigated in approximately 10% of its species. Hence, the systematic value of architectural design and organization of internal floral parts has remained virtually unexplored in the family. This study represents the most extensive survey of flower and nectary morphology in the Cactaceae focusing on tribes Hylocereeae and Rhipsalideae (subfamily Cactoideae). Our objectives were (1) to conduct comparative morphological analyses of flowers and floral nectaries and (2) to compare nectar solute concentration in these two tribes consisting of holo- and semi-epiphytic species. Flower morphology, nectary types, and sugar concentration of nectar have strong taxonomic implications at the tribal, generic and specific levels. Foremost, three types of nectaries were found, namely chamber nectary (with the open and diffuse subtypes), furrow nectary (including the holder nectary subtype), and annular nectary. All Hylocereeae species possess chamber nectaries, in which the nectarial tissue has both trichomes and stomata. The Rhipsalideae are distinguished by two kinds of floral nectaries: furrow and annular, both nectary types with stomata only. The annular nectary type characterizes the genus Rhipsalis. Nectar concentration is another significant taxonomic indicator separating the Hylocereeae and Rhipsalideae and establishing trends linked to nectar sugar concentration and amount of nectar production in relation to flower size. There is an inverse relationship between flower size and amount of nectar production in the smaller Rhipsalideae flowers, in which nectar concentration is more than two-fold higher despite the smaller volume of nectar produced when compared to the large Hylocereeae flowers. Variability of nectary morphology and nectar concentration was also evaluated as potential synapomorphic characters in recent phylogenies of these tribes. In conclusion, our data provide strong evidence of the systematic value of floral nectaries and nectar sugar concentration in the Cactaceae, particularly at different taxonomic levels in the Hylocereeae and Rhipsalideae.

Natural variation in floral nectar proteins of two Nicotiana attenuata accessions.

BackgroundFloral nectar (FN) contains not only energy-rich compounds to attract pollinators, but also defense chemicals and several proteins. However, proteomic analysis of FN has been hampered by the lack of publically available sequence information from nectar-producing plants. Here we used next-generation sequencing and advanced proteomics to profile FN proteins in the opportunistic outcrossing wild tobacco, Nicotiana attenuata.ResultsWe constructed a transcriptome database of N. attenuata and characterized its nectar proteome using LC-MS/MS. The FN proteins of N. attenuata included nectarins, sugar-cleaving enzymes (glucosidase, galactosidase, and xylosidase), RNases, pathogen-related proteins, and lipid transfer proteins. Natural variation in FN proteins of eleven N. attenuata accessions revealed a negative relationship between the accumulation of two abundant proteins, nectarin1b and nectarin5. In addition, microarray analysis of nectary tissues revealed that protein accumulation in FN is not simply correlated with the accumulation of transcripts encoding FN proteins and identified a group of genes that were specifically expressed in the nectary.ConclusionsNatural variation of identified FN proteins in the ecological model plant N. attenuata suggests that nectar chemistry may have a complex function in plant-pollinator-microbe interactions.

Anatomy of the floral nectary of ornithophilousElleanthus brasiliensis(Orchidaceae: Sobralieae)

Orchidaceae show enormous floral diversity. However, anatomical studies of nectary tissues relative to nectar composition and pollinators are scarce. This work aims to present a detailed anatomical study of the labellar nectary of Elleanthus brasiliensis, analyse the chemical composition of its nectar and relate these findings to pollination biology. Basally, the labellum bears a pair of fleshy, whitish, ovoid calli on its adaxial surface. Nectariferous callus tissue consists of a papillate epidermis and enlarged subepidermal parenchyma cells with thin walls, large nuclei and dense cytoplasm which stained positively for hydrophilic substances, interpreted as pre-nectar. The paired calli lack vascular tissues, but at the point of callus insertion, the diameters of vascular bundles supplying the lip are larger. Nectar is secreted as droplets on the adaxial callus surface. It is produced in small quantities, c. 4 μL per flower. Callus cell contents tested negative for polysaccharides, lipids and phenolic compounds. The nectar is sucrose-dominant, as in other hummingbird-pollinated species. It is suggested that other ornithophilous species of Sobralieae have anatomically similar nectaries.

Nectar production in the pollen flower of Anemone nemorosa in comparison with other Ranunculaceae and Magnolia (Magnoliaceae)

The observation that the flowers of Anemone nemorosa offer nectar to pollinating bee-flies (Bombylius major) prompted this investigation into the site of nectar secretion and nectary tissue. To allow comparison on a broader basis, other nectar-secreting pollen flowers of the Ranunculaceae and Magnolia (Magnoliaceae) were included in the analysis. The contradictory information available on the function of the mouthparts of bee-flies during nectar and pollen feeding motivated us to investigate the proboscis structure in detail by SEM. Our investigations in Anemone nemorosa proved, for the first time, nectar secretion in the genus Anemone s.s. (i.e. other than the Pulsatilla group) and in addition, within the family, a new type of a carpellary nectary. The latter is an epithelial nectary involving the whole epidermis of the ovarian part of the carpel. The nectary of Anemone nemorosa resembles that of Magnolia (e.g. M. stellata), which we re-investigated. In both Anemone nemorosa and Magnolia stellata, nectar production is limited mainly to the female phase of the proterogynous flower. In this way, the attractiveness of the flower is also assured in the non-pollen presenting phase. Especially in Magnolia, with its numerous carpels arranged on a cone-like receptacle, the economic disadvantage of a choricarpous- compared to a coenocarpous-gynoecium is compensated for by nectar secretion by each carpel. When licking up the nectar droplets from the carpel surfaces, contact of the insect's body with each stigma may be achieved.

The morphology and ultrastructure of the nectaries of marrow (Cucurbita pepo L. convar. giromontiina)

The present study investigated the size and structure of the nectaries in flowers of marrow – <em>Cucurbita pepo </em>convar.<em> giromontiina </em>cv. ‘Weiser Busch’. The diameter and thickness of nectariferous layer were compared in female and male flowers of this taxon. The micromorphology as well as the anatomical and ultrastructural characters of the nectary from the female flower were observed using light, scanning and transmission electron microscopy. The density and size of stomata of the nectary epidermis from both types of flowers were examined using light microscopy. The nectaries in female flowers were found to have a larger size than in male flowers. The stomata occurring in the nectary epidermis of both types of flowers have a similar size and density. We observed that nectar was released onto the surface of the nectary not only via the stomata, but also through the walls of the epidermal cells. In TEM examination, large nuclei, different-shaped plastids, ER tubules, dictyosomes, and ribosomes were observed in the nectariferous tissue cells. A large number of mitochondria accompanying the plastids were found in the parenchyma cells of the nectary. The degradation of the nectary parenchyma cells in the flowers living for about 6 hours was asynchronous.

Морфологія та васкулярна анатомія квітки Scilla bifolia L. (Hyacinthaceae)

Morphology and vascular anatomy of the flower of Scilla bifolia L. (Hyacinthoideae) were studied. Based on the concept of vertical zonation of gynoecium, proposed by W. Lein­fellner [7], it is established that the gynoecium has the following structural zones: synascidiate, symplicate, hemisymplicate, and asymplicate. In a broad sense gynoecium of Scilla bifolia can be determined as syncarpous. The septal nectary has three fissures lying in a septal radius which extend from its base to the roof and open outward at the base of the style; nectariferous tissue lines a septal slit completely except output channels. Structural type of septal nectaries of Scilla bifolia corresponds to the type a, the type of glandular epidermis is determined as type a by E. Daumann [6]. All tepals and stamens are supplied by single bundle. Vascular system of the gynoecium has six ventral and three dorsal veins which branch lateral veins. Ventral bundles coalesce with dorsal bundles at the top of the ovary. The septal nectary is innervated by lateral carpel veins. Keywords: Hyacinthoideae, Scilla bifolia , flower, morphology, vascular anatomy, septal nectary, gynoecium.

A light in the shadow: the use of Lucifer Yellow technique to demonstrate nectar reabsorption

BackgroundNectar reabsorption is a widely known phenomenon, related to the strategy of resource-recovery and also to maintain the nectar homeostasis at the nectary. The method currently performed to demonstrate nectar being reabsorbed involves the use of radioactive tracers applied to the nectary. Although this method works perfectly, it is complex and requires specific supplies and equipment. Therefore, here we propose an efficient method to obtain a visual demonstration of nectar reabsorption, adapting the use of Lucifer Yellow CH (LYCH), a fluorescent membrane-impermeable dye that can enter the vacuole by endocytosis.ResultsWe applied a LYCH solution to the floral nectary (FN) of Cucurbita pepo L., which is a species known for its ability of nectar reabsorption, and to the extrafloral nectary (EFN) of Passiflora edulis Sims which does not reabsorb the secreted nectar. In all tests performed, we observed that LYCH stained the nectary tissues differentially according to the reabsorption ability of the nectary. The treated FN of C. pepo presented a concentrated fluorescence at the epidermis that decreased at the deeper nectary parenchyma, until reaching the vascular bundles, indicating nectar reabsorption in the flowers of the species. In contrast, treated EFN of P. edulis presented fluorescence only at the cuticle surface, indicating that nectar is not reabsorbed by that particular tissue.ConclusionLYCH is an efficient marker to demonstrate nectar reabsorption.

Comparison of the nectary structure of chosen species from subf. Pomoideae (Rosaceae)

The research of the anatomy of nectaries of six species from <em>Pomoideae</em> was carried out. The observations concerned the flowers longitudinal sections of the following species: <em>Malus silvestris</em> Mill., <em>Pyrus communis</em> L., <em>P. ussuriensis</em> Maxim., <em>Cydonia oblonga</em> Mill., <em>Chaenomeles japonica</em> Ldl. and <em>Ch. speciosa</em> Nakai. It was stated, that the nectary glands distinguished themselves by the dimension of section surface, thickness of layers, the sizes of glandular and epidermis cells. A considerable difference of external wall thickness among epidermis cells was also observed. The nectaries of the smallest size, consisting of the tiniest cells occurred in <em>Malus silvestris</em>. Whereas, the biggest ones were possessed by <em>Cydonia oblonga</em>. Here the nectaries had maximum section surface, thickness, number of layers and cell dimension. The nectary epidermis of <em>Pyrus</em> was characterized by the thinnest external wall. The Chaenomeles speciosu and <em>Cydonia oblonga</em>, by the thickest one with a massive cuticle layer. The vascular bundles reaching the nectary tissue consisted of phloem and xylem. The positive dependence between the nectary dimension and the abundance of nectar secretion in some species, and the occurence of the opposite tendency in the others is discussed.

Anatomy, ultrastructure, and secretory activity of the floral nectaries in Swietenia macrophylla (Meliaceae)

While mahogany (Swietenia macrophylla) is one of the most important forest species in the Amazon region, little is known about its reproductive biology. Knowledge about the nectary structure and dynamics of nectar production of this species represent a key step toward understanding its relationship with pollinators. • Mahogany tree floral buds and flowers in anthesis were collected, fixed, and processed for study by light and transmission and scanning electron microscopy. The chemical composition of nectar and the nectary pigments was also studied. • Both staminate and pistillate flowers have nectaries, which contain a papillose epidermis and stomata. The nectariferous tissue is parenchymatous, with the cell cytoplasm primarily containing mitochondria and plastids. Secretory activity initiates at the beginning of anthesis, which occurs at nightfall. Flowers undergoing anthesis become structurally modified, with starch grains in the plastids disappearing. The number of plastoglobuli in the plastids also increases when nectaries change color from pale yellow to intense red. Pistillate and staminate flowers produce meager nectar rewards. • Changes in plastoglobuli number seem to be related to an increase in carotenes and color changes during anthesis. Carotenes can be linked to the protection of the plant against oxidative stress, which results from secretory activities. Nectary color has a limited role as a pollinator attractant. Floral rewards comprise small nectar droplets in both flower types, in addition to a few pollen grains in staminate flowers. These meager rewards are probably adapted to attract small generalist insects.

Studies on the Structure of Flowers and Inflorescences of Cornelian Cherry (Cornus mas L.)

This study reports on the arrangement of flower buds and structure of floral organs of cornelian cherry (Cornus mas L.) cultivars local to Turkey. The local cultivars were investigated under stereo microscope, light microscope, and scanning electron microscope (SEM). The results indicate that each node has two oppositely positioned buds on 1-year-old shoot. Inflorescences resembled the umbel structure that enclosed four (two sets of oppositely oriented) bud scales. The mean flower number varied between 16.3 and 19.9 per cluster among the cultivars. The flowers resembled the hermaphrodite type and one flower was found to have four rudimentary sepals, four petals, four stamens, and one pistil. The stamens were noted to be arranged around the base of the ovary. Each normal anther was observed to have two pollen-producing theca, and each theca was found to have two locules. The number of pollen grains per anther varied between 1380 and 4240 among the genotypes. The pistil was noted to have a deeply hollowed papillate stigmatic surface, and the central part of the style had conducting tissue. The ovarium part of the pistil was found to be surrounded by the nectary tissue, inferior type, and had two atropous ovules. The fruit resembled single-seeded, stone fruit type. This study is the first detailed study on the flower morphology and inflorescences of the cornelian cherry cultivars in Turkey.

Developmental Anatomy of Floral Nectary in Thymus marschallianus Willd

The floral nectary of Thymus marschallianus Willd is located on the base of ovary receptacle,disk-like,which inflated after mature and surrounded around the receptacle.The top of the floral nectary is divided into 4 same size slices.The nectary is composed of epidermis,nectariferous tissue and vascular bundles.Histochemistry staining showed that the starch grains were accumulated in the beginning and the later stages of nectary development,so the nectary belonged to non-starch nectary.During the development of nectary,the morphological changes of vacuoles are obvious,but the changes of starch grains and polysaccharide are not obvious.It is suggested that the nectar is transported from phloem to nectariferous tissue and then excreted by permeation through the thin cuticle of epidermis.

Extrafloral Nectaries in Acacia mangium

Our microscopy studies describe the anatomy of extrafloral nectaries on the abaxial side of the basal part of every leaf stalks of Acacia mangium. The lens-like nectary expands with the development of the leafstalk, peaks at the stage at which the leafstalk itself has reached its mature size. The nectary is composed of numerous small parenchyma cells and a nectar cavity in which the nectar is pooled. Those small parenchyma cells are divided into nectariferous tissue and epithelial cells, which line the lumen of the nectar cavity, and secretes the nectar into the same. Each nectary is surrounded by several vascular bundles, which probably afford the nectar. In addition to the microscopic observation, the chemical constituents of the nectar are analyzed by NMR, and it mainly consists of sugars with 60 % sucrose, 25 % glucose and 15 % fructose.

Functional aspects of floral nectar secretion of Ananas ananassoides, an ornithophilous bromeliad from the Brazilian savanna.

Several members of Bromeliaceae show adaptations for hummingbird pollination in the Neotropics; however, the relationships between floral structure, nectar production, pollination and pollinators are poorly understood. The main goal of this study was to analyse the functional aspects of nectar secretion related to interaction with pollinators by evaluating floral biology, cellular and sub-cellular anatomy of the septal nectary and nectar composition of Ananas ananassoides, including an experimental approach to nectar dynamics. Observations on floral anthesis and visitors were conducted in a population of A. ananassoides in the Brazilian savanna. Nectary samples were processed using standard methods for light and transmission electron microscopy. The main metabolites in nectary tissue were detected via histochemistry. Sugar composition was analysed by high-performance liquid chromatography (HPLC). The accumulated nectar was determined from bagged flowers ('unvisited'), and floral response to repeated nectar removal was evaluated in an experimental design simulating multiple visits by pollinators to the same flowers ('visited') over the course of anthesis. The hummingbirds Hylocharis chrysura and Thalurania glaucopis were the most frequent pollinators. The interlocular septal nectary, composed of three lenticular canals, extends from the ovary base to the style base. It consists of a secretory epithelium and nectary parenchyma rich in starch grains, which are hydrolysed during nectar secretion. The median volume of nectar in recently opened 'unvisited' flowers was 27·0 µL, with a mean (sucrose-dominated) sugar concentration of 30·5 %. Anthesis lasts approx. 11 h, and nectar secretion begins before sunrise. In 'visited' flowers (experimentally emptied every hour) the nectar total production per flower was significantly higher than in the 'unvisited' flowers (control) in terms of volume (t = 4·94, P = 0·0001) and mass of sugar (t = 2·95, P = 0·007), and the concentration was significantly lower (t = 8·04, P = 0·0001). The data suggest that the total production of floral nectar in A. ananassoides is linked to the pollinators' activity and that the rapid renewal of nectar is related to the nectary morphological features.

Developmental anatomy of the floral nectaries in Dracocephalum nutans Linn.

The nectaries in Dracocephalum nutans Linn.were located on receptacles under the ovary.The disk nectar upper split into four pieces a list,base in swollen reflexed round the lap cup-shaped receptacle.The nectary composed of secretory epidermis,nectariferous tissue and vascular bundles,which was typical structural nectary.Histochemistry stain indicated that the starch grain exhibited a regular change,hence the nectary belonged to starch nectary.During the development of nectaries tissue,the vacuole occured regular change and the starch grains and protein decreased and increased regularly.The nectar was secreted out through stomata and cuticle.

Comparison of features of the epidermis and the size of the floral nectary in four species of the genus Cotoneaster Med.

The investigations involved four species of the <i>Cotoneaster</i> genus: <i>C. divaricatus</i>, <i>C. horizontalis</i>, <i>C. lucidus</i>, <i>C. praecox</i>, which are commonly grown for decorative purposes. In Poland, these plants bloom in May and June and are a source of abundant spring nectar flow for insects. The floral nectaries of the above-mentioned species were examined using stereoscopic, light, and scanning electron microscopy in order to assess their size and epidermal microstructure. In the plants studied, the upper part of the hypanthium is lined by nectariferous tissue. The nectaries in the four species vary in terms of their sizes. Nectar is secreted onto the surface of the epidermis through anomocytic, slightly elongated or circular stomata. The largest stomata on the nectary epidermis were found in the flowers of <i>C. horizontalis</i>, and the smallest ones in <i>C. divaricatus</i>.Their size and location in relation to other epidermal cells were taxon-specific. The highest density of stomata in the nectary epidermis was found in <i>C. divaricatus</i> (205 per mm<sup>2</sup>), whereas <i>C. horizontalis</i> flowers exhibited the lowest (98 per mm<sup>2</sup>) stomatal density. The cuticular ornamentation on the nectary epidermis surface was diverse. The stomatal indices calculated for the nectary epidermis were considerably lower than for the leaves in the particular species.

Structure of nectaries of Malus sylvestris (L.) Mill.

The structure of floral nectary of <i>Malus sylvestris</i> was examined using light and scanning electron microscopy. Nectaries in <i>M. sylvestris</i> flowers were situated on the adaxial surface of the receptacle, between the style and the base of filaments. The middle part of the nectary was covered epidermal cells with striated cuticle. The remaining part of the nectary was covered with smooth cuticle. Open and modified nectarostomata were situated at the same level as epidermal cells. The nectariferous tissue was formed by densely packed small parenchyma cells (secretory cells) with dark protoplasts.

Anatomy and ultrastructure of floral nectaries of Asphodelus aestivus Brot. (Asphodelaceae)

The structure of septal nectaries in <i>Asphodelus aestivus</i> flowers was investigated by using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (EM). It was found that the outlets of the three parts of the nectary were situated on the ovary surface at 2/3 of its height and had the shape of elongated openings. The nectariferous tissue was in the septa of the lower part of the ovary. The secretory tissue cells formed 1-3 layers surrounding the nectary slits. They contained thin cell walls with the cuticle layer from the slit side, large cell nuclei, numerous mitochondria and plastids characterised by various shapes. In plastids, small starch grains occurred sporadically. At the beginning of anthesis, the cells were poorly vacuolized. ER cisternae and secretory vesicles were located near the outer cell wall. Fibrous substance was present in the nectary slits. In the subglandular tissue, numerous starch grains occurred at the beginning of anthesis. In this zone, cells containing raphides and xylem elements were observed. Based on the ultrastructure of the nectary it can be stated that granulocrine nectar secretion occurs in <i>A. aestivus</i>.

Micromorphology of flowers, anatomy and ultrastructure of Chamomilla recutita (L.) Rausch. (Asteraceae) nectary

Investigations of the micromorphology of flowers and the structure of nectaries in <i>Chamomilla recutita</i> L. (Rausch.) were carried out with the use of stereoscopic, light, scanning and transmission electron microscopy. Biseriate glandular trichomes consisting of 5-6 cell layers were found on the surface of the corollas of ray and disc florets. Accumulation of secretion within the subcuticular space was accompanied by degradation of trichome cells. Secretion release followed rupture of the cuticle in the apical part of the trichome. The ovary of the ray florets exhibited characteristic ribs covered with epidermis composed of radially elongated palisade cells. Nectariferous glands were present only in the disc florets. The ring-like nectary (93 × 163 µm; height × diameter) was located above the inferior ovary. The gland structure was formed by single-layer epidermis and 5-8 layers of specialised nectariferous parenchyma. Nectar was released via modified 15-20 µm wide stomata. The guard cells were slightly elevated above the surface of the other epidermal cells or were located slightly below them. The stomatal cells were characterised by small external and internal cuticular ledges. No vascular bundles were observed in the nectary. The gland was supplied by branches of vascular bundles reaching the style and ending at the nectary base. The nectariferous tissue was formed by isodiametric cells with a diameter of 11-20 µm. The cell interior was filled with electron dense cytoplasm containing a large nucleus, numerous pleomorphic plastids, mitochondria with a distinct system of cristae, Golgi bodies, ER profiles, and ribosomes. The plastid stroma was characterised by presence of pastoglobuli, intraplastid tubules, and lighter zones. Several small vacuoles were found in each cell. Plasmodesmata were visible in the walls of some cells. Lighter periplasmic space in which apoplastic transport of nectar might take place was observed between the plasmalemma and the cell wall. The presence of an osmiophilic substance in the intercellular spaces additionally corroborates this assumption.

Flowering biology and nectary structure of Melissa officinalis L.

The present study on lemon balm (<i>Melissa officinalis</i> L.) covered flowering biology, monitoring of pollinating insects and floral nectary structure. The micromorphology of epidermal cells of the nectary was investigated using scanning electron microscopy. The nectariferous tissues were observed using light microscopy based on semi-thin sections. Lemon balm flowered from the second decade of June until September. Buds opened from early morning hours until noon. Flowers lived for 24 hours, on the average. Their primary pollinator was the honey bee. The beginning of nectar secretion was found to be at the bud swell stage. The automorphic nectary forms a disc with four protrusions at the base of the nectary. Three smaller ones and one larger than the other ones were distinguished among them. No stomata were found on the lower protuberances, whereas on the highest part anomocytic stomata were present, the number of which was 15. The stomata exhibited different development stages and they were situated above other epidermal cells. In their outline, they were ellipsoidally shaped (18 × 23 µm) and they had average-sized cuticular ledges. They produced a smooth cuticle and wax granules. In cross section, the nectary tissues were composed of a singlelayered epidermis and 9 - 11 layers of the nectary parenchyma. Their thickness was 198 µm. In longitudinal section, the height of the nectary was within a range of 354 - 404 µm. The epidermal cells produced thin outer cell walls. Some of them were completely filled with strongly stained cytoplasm, whereas others showed a high degree of vacuolisation. But the nectary parenchyma cells were marked by poorly stained cytoplasm, a large nucleus and vacuolisation of varying degree.