Floral Nectaries of Rosmarinus officinalis L. Structure, Ultrastructure and Nectar Secretion

The nectary of Rosmarinus officinalis L. has the form of a four-lobed,asymmetrical disc situated around the base of the ovary. Thenectary lobe facing the lower flower lip is enlarged and isthe only one to have modified stomata. Vascular strands consistingof phloem only occur in the nectariferous tissue. It is suggestedthat the pre-nectar originating in the phloem accumulates primarilyas starch grains in plastids of the nectariferous cells. Thenumber of grains is very large before anthesis and decreasesconsiderably at anthesis. The transport of the pre-nectar tothe various nectariferous cells appears to be mainly via thesymplast. It could not be determined whether the process ofelimination of the nectar is solely eccrine or partly granulocrine. Rosmarinus officinalis, nectary, nectar secretion, starch grains, phloem     

The Floral Nectary of Tropaeolum majus L.--The Nature of the Secretory Cells and the Manner of Nectar Secretion

The floral nectary of Tropaeolun majus L. was studied with theaid of a microscope with transmitting and incident light, atransmission electron microscope and a scanning electron microscope.The Gomori method was used for the localization of acid phosphatase.As a result of this investigation the previously accepted viewthat nectar in this plant is secreted only from the hair tipsof the inner epidermis of the calyx spur was found to be inaccurate.The present studies showed that the parenchyma cells locatedbetween the inner epidermis and the region of the vascular bundlesof the lowest third of the spur, are the main nectar-secretingelements of the nectary. These secretory cells release the nectarsolution into intercellular spaces leading to modified stomata,through which it is exuded into the spur cavity. The modifiedstomata occur in the lowest portion of the spur only. At thestage of secretion small droplets of liquid of high viscositywere observed on the epidermal hairs. These droplets presumablycontain polysaccharides and a certain amount of sugar.     

Structural and Functional Properties of Trichomes of Xeromorphic Leaves

Trichomes of xeromorphic leaves of 12 different species (Banksiaspeciosa, Corokia buddleioides, Correa backhousiana, Lavandulaofficinalis, Leucospermum grandiflorum, Metrosideros excelsa,Olea europaea, Olearia rotundifolia, Pittosporum crassifolium,Pittosporum sp., Rosmarinus officinalis, Senecio cineraria)and trichomes of mesomorphic leaves of five species (Achimenesgrandiflora, Geum urbanum, Gynura aurantiaca, Populus alba,and Styrax officinalis) were stained with Sudan IV and Sudanblack. In the trichomes of all xeromorphic leaves the wallsof the basal or stalk cells stained with these reagents. However,none of the cell walls of the trichomes of the mesomorphic leaveswere stained by the Sudan reagents. Portions of leaves of three of the xeromorphic species (Corokia,Correa, Olea) and leaves of three of the mesomorphic species(Achimenes, Geum, Gynura) were floated on 0.1 per cent Calcofluorwhite solution. Examination of cross-sections of these leafportions in the fluorescence microscope indicated that evenafter 4 days of floating the Calcofluor, which is an apoplastictracer, did not enter the trichome walls of the xeromorphicleaves. However, the Calcofluor brightener could already bedetected in the trichome walls of the mesomorphic leaves afterone day. The adapted properties of the trichomes of the xeromorphic leavesare discussed. Endodermal cell, mesomorphic leaves, trichomes, xeromorphic leaves, water diffusion boundary layer     

Ultrastructure of the Resin Ducts of Mangifera indica L. (Anacardiaceae). 2. Resin Secretion in the Primary Stem Ducts

The resin of the mango stem consists mainly of terpenes. Theterpenes seem to be produced primarily by plastids, termed heresecretoplasts. At the beginning of the process of secretion,osmiophilic droplets are seen at the envelope of the secretoplastsand at elemints of periplastidal ER. In addition, such dropletsoccur also at Golgi bodies and occasionally in association withmitochondria. Later osmiophilic material fills the well-developbdER, which at this stage is mainly tubular. It appears that theER is involved in the transport of the sareted material towardsthe plasmalemma. Mangifera indica L., mango, Anacardiaceae, resin, resin ducts, secretion, secretoplasts, ultrastructure     

Ultrastructure of Resin Ducts in Pinus halepensis Development, Possible Sites of Resin Synthesis, and Mode of its Elimination from the Protoplast

Development of the resin duct cavity, sites of resin synthesisin the epithelial cells and elimination of resin from the protoplastwere studied in roots of young Pinus halepensis seedlings. Itis suggested that the Golgi bodies are involved in dissolutionof the middle lamella in the region of the future duct cavityby secretion of lytic enzymes into the cell walls. In earlystages of duct development osmiophilic droplets were observedin plastids, periplastidal and cytoplasmic ER, Golgi vesicles,mitochondria, nuclear envelope and in the cytoplasm. In thelatter they were often observed to be surrounded by a membrane.Electron micrographs suggested that elimination of resin dropletsfrom the protoplast occurs by their becoming surrounded by plasmalemmainvaginations.     

Development of the glandular and non-glandular leaf hairs of Avicennia marina (Forsskål) Vierh.

The course of development of the glandular and non-glandular hairs of Avicennia marina was found to be the same up to the three-celled stage. The further cell divisions of the two types of developing hairs differed in their orientation. In the non-glandular hair the cells continued to divide transversely, whereas in the glandular hair the uppermost of the three cells divided longitudinally.
In the mature hairs of both types, the peripheral wall of the cell just above the basal cell was heavily cutinized. The existence of narrow canals in the cuticle of the secretory cells of the glandular hairs was confirmed. The homology of the glandular and non-glandular hairs is discussed and it is concluded that the two types are phylogenetically related.     

Cambial Activity in Acacia raddiana Savi

Cambial activity and extension growth of Acacia raddiana Saviwere investigated. Both types of growth are strongly dependenton relatively high temperatures. In contrast with the behaviourof the cambium of trees with a clear interrupted growth period,the cambium of A. raddiana saplings did not respond to the twodifferent photoperiods tried. A correlation between extension growth and cambial activitycould not always be observed. The cambium was always activeonly in young green twigs, and in their close proximity, underconditions where intensive extension growth took place. In oldertwigs the cambial activity was found to occur independentlyof the extension growth, even in the very same branches in whichextension growth occurs.