The structure of floral nectaries of some species of Vicia L. (Papilionaceae)

The subject of research were morphology and ultrastructure of floral nectaries of nine species of <i>Vicia</i>. The differences in their size and morphological structure were shown. Small, almost flat nectaries appeared in flowers of <i>Vicia tetrasperma</i> and <i>V. hirsuta</i>. Much better developed ones which had convexities with the shape of a protuberance, a half-ring or a half -ring with a ligulate outgrowth were observed in <i>V. silvatica</i>, <i>V. cracca</i>, <i>V. villosa</i>, <i>V. sativa</i> and <i>V. angustifolia</i>. Completely convex, annular nectaries with a ligulate outgrowth belonged to <i>V. sepium</i> and <i>V. grandiflora</i>. Small anatomical differences concerned mainly the structure and distribution of vascular bundles, whereas ultrastructure of secretory cells was very similar. Nectar got into the surface through the modified stomata situated on the top of nectaries' convexities.

Micromorphology and anatomy of flowers and nectaries of Saxifraga stolonifera L.

Saxifrages are plants commonly found in all continents. Many of them are adapted to flowering and reproduction under mountainous and rocky conditions. They are pollinated by various groups of insects and have intrastaminal nectaries. The morpho-anatomy of the flowers and nectaries of <em>Saxifraga stolonifera</em> L. was examined using bright-field light and stereoscopic microscopy as well as scanning electron microscopy. The abaxial surface of the sepals has multicellular glandular trichomes containing anthocyanins in the base cells and polyphenols in the secretory cells of the head, whereas visual attractants in the form of color spots are found on the petals. The nectary gland is located at the apex of the ovary and forms a yellow-orange fleshy half-ring. Nectar is secreted through numerous modified stomata. The glandular parenchyma does not have vascular elements. Moreover, orange-brown polyphenols were observed in the nectary cells.

Nectar secretion in the flowers of comfrey (Symphytum officinale L.) and nectar chemistry

Nectar secretion and nectar chemistry in the flowers of comfrey (<i>Symphytum officinale</i> L.) were examined in the four stages of anthesis: large buds, before pollen exposure: II - freshy opened flowers with the beginning of anther dehiscence: III- completely opened flowers in the maximum of pollen exposure: lV- flowers at the final stage of anthesis, without pollen in the anthers. Individual flower stays fresh 2,5-3 days, on average. Disc-shaped nectaries of S.officinale are located at the base of the four-lobbed ovary. Nectar is released through the modified stomata. Start of nectar secretion was noted at the bud stage. Nectar volume, mass of nectar and sugars differed in the examined stages of anthesis and the biggest values were noted at the final stages. Dominant sugar in nectar was sucrose with smaller amounts of fructose and glucose. The presence of amino acids was also recorded.

Flowering and nectar and pollen flow in Geranium sanguineum L., Geraniaceae

This 3-year study examined the seasonal and daily dynamics of blooming, as well as the nectar and pollen production in <i>Geranium sanguineum</i> L. Moreover, the type and localization of floral nectaries were observed using LM and SEM, and measurements of pollen grains were performed. The visitation of insects on flowers was monitored, too. <i>Geranium sanguineum</i> bloomed from the beginning of May until the middle of July with the peak occurring between the second and the fifth week of flowering period. Most of the flower buds opened on plants in the afternoon hours. Flowers are protandrous. In a flower, nectar is secreted by five phanarothetic-discoid nectaries and it flows through modified stomata. It was found that one gland is bigger than the others. Ten flowers produced 30.58 mg of highly concentrated nectar, on average. The mean mass of total sugars secreted in nectar per 10 flowers was 7.94 mg. Pollen mass per 10 flowers was 23.14 mg, on average. Tricolpate, spherical pollen grains can be classified as very big size (sporae permagne). Flowers of <i>G. sanguineum</i> were visited mainly by honey bees, bumble bees and flies. Insects collected mainly nectar.

Anatomy and ultrastructure of floral nectary of lnula helenium L (Asteraceae)

Floral nectaries of <em>Inula helenium</em> L. only occurred in disc florets and were situated above the inferior ovary. The shape of the investigated glands (five-armed star with rounded tips and deep incisions - observed from above) clearly differed from the shape of the nectaries of other <em>Asteraceae</em>, also the height of nectary was much lower (129 µm). The glandular tissue of the nectaries of elecampane was composed of a single-layered epidermis and 5--9 layers of secretory cells. Nectar was released through modified stomata, mainly arranged in the top part of the gland. The secretory cells were characterised by granular cytoplasm and the presence of a large, often lobate, cell nucleus. In the cytosol, numerous amoeboid plastids, mitochondria, Golgi bodies and ribosomes were present. In small vacuoles, myelin-like structures, fibrous material and vesicles with the content of substances which can be secretion, were observed. The plastid stroma showed different electron density and the presence of internal tubules and plastoglobules. Vesicular extensions forming bright zones were visible between the membranes of the nuclear envelope. Adjacent to the plasmalemma, as well as between the plasmalemma and the cell wall, secretory vesicles occurred, indicating the granulocrine mechanism of nectar secretion.