Epidermal Structure and Ontogeny of Stomata in some Verbenaceae

The present paper deals with epidermal structure and developmentof stomata in 14 species of Verbenaceae. The epidermal cellsare either polygonal, isodia-metric, or elongated in variousdirections, and irregularly arranged. The anticlinal walls arethick, mostly sinuous, occasionally arched or straight. Thesurface of the cuticle shows parallel, rarely corrugated, striations.Some 12 types of eglandular and glandular trichomes, and foliarnectaries are noticed. The mature stomata are diacytic, anisocytic,paracytic, with a single subsidiary cell, anomocytic and perigenous.The development of anomocytic stomata is perigenous, while thatof others is mesogenous or syndetocheilic type. Abnormalitiesnoticed here include contiguous stomata, stomata with a singleguard cell, and aborted guard cells.     

Epidermal Structure and Ontogeny of Stomata in Vegetative and Reproductive Organs of Ephedra and Gnetum

The epidermal structure and development of stomata in vegetativeand reproductive organs of Ephedra foliata and Gnetum ula isdescribed. The epidermal cells are polygonal, isodiametric,or elongated with thick or thin straight, arched, or slightlysinuous anticlinal walls. The cuticle is thin or thick. Papilla-likeunicellular outgrowths are present in Ephedra foliata. The maturestomata are orientated parallel to the longitudinal axes orirregularly. The mature stomata are anomocytic, paracytic, witha single subsidiary cell, cyclocytic, and actinocytic. Arresteddevelopment, contiguous stomata, and stomata with aborted guardcells have been observed. The ontogeny of stomata on differentorgans of these two plants is typically haplocheilic or perigenousbut the stomatal apparatus varies from organ to organ.     

Development of Normal and Abnormal Stomata in some Araliaceae

The present investigation describes the ontogeny of normal andabnormal stomata for three species of the Araliaceae. The maturestomata are mostly anisocytic, occasionally paracytic, and rarelyanomocytic. Several aberrent patterns of stomatal developmenthave been noticed in anisocytic stomata and a few in paracyticones. The ontogeny of anisocytic and paracytic stomata conformsto the syndetocheilic or mesogenous type, while that of anomocyticis haplocheilic or perigenous.     

Distribution, Development and Structure of Resin Ducts in Guayule (Parthenium argentatum Gray)

The distribution, development and structure of resin ducts inguayule (Parthenium argentatum Gray), the second best sourceof natural rubber, have been studied. Resin ducts are widelydistributed in stem, root, leaf, petiole and peduncle. The ductsin the primary tissues are initiated schizogenously and theirfurther development is schizolysigenous. The ducts in the cortexof the root do not have a well-defined epithelium. Ducts developedfrom the vascular cambium are initiated and develop schizogenously.Both resin and rubber are produced in the epithelial cells ofresin ducts. While resin is secreted into the duct lumen, rubberis stored within these cells. Epithelial cells store more thanneighbouring parenchyma cells. Guayule, rubber, resin, ducts, epithelial cells     

Ultrastructure of Non-Articulated Laticifers in Allamanda violacea

Ultrastructure studies on the differentiation of non-articulatedbranched laticifers in Allamanda violacea Gardn. were carriedout. Growing laticifers show sequential changes. In the earlystage, the laticifers possess electron dense cytoplasm, abundantmitochondria, ER, ribosomes, small vacuoles, nucleus and plastidwith starch-grains. The ER dilates to form small vacuoles whichcoalesce at the later stages. A large central vacuole is formedin the mature laticifers due to the cellular autophagy of cytoplasmincluding the cell organelles. At this stage, the mitochondriapossess a few cristae and plastids with plastoglobuli and smallstarch grains. Towards the end of differentiation the cytoplasmis restricted to a thin parietal layer along the cell wall,the remaining organelles being either reduced in number or degenerate.Plasmodesmata and primary pit fields are occasionally observedbetween the laticifer and the adjacent parenchyma cell. Allamanda violacea, laticifers, ultrastructure     

Structure and Development of Stomata in Some Labiatae

The structure and ontogeny of stomata have been studied in 33species of the Labiatae. The mature stomata are diacytic, transitionalbetween paracytic and diacytic, and anomocytic. The anomocyticstomata are haplocheilic or perigenous. The diacytic and thetransitional type of stomata are syndetocheilic or mesogenousas the two subsidiary cells and a pair of guard cells arisefrom the same meristemoid. The diacytic and the transitionalstomata are formed through three successive mitotic divisions.Abnormal stomata with single guard cells, arrested developments,and contiguous stomata have been observed. Contiguous stomataare formed either from two adjacently placed meristemoids orare the result of spatial readjustment during maturation ofthe leaf.     

Epidermal Structure and Stomatal Development in Some Malvaceae and Bombacaceae

Epidermal structure and development of stomata in 15 speciesof the Malvaceae and two of Bombacaceae are described. The cellsof the epidermis are polygonal, isodiametric, or elongated withthick, straight, arched, or sinuous anticlinal walls and containchloroplasts and abundant druses of calcium oxalate. Cuticularstriations radiating from the guard cells or hair bases arenoticed. Six types of glandular and non-glandular trichomesare seen. The mature stomata are anomocytic, anisocytic, andparacytic in the members investigated of both the families.The ontogeny of anisocytic and paracytic stomata is syndetochelicor mesogenous, while that of anomocytic is haplocheilic or perigenous.An abnormal stoma with a single guard cell is also observed.An increase in number of subsidiary cells in anisocytic stomatais due to the division of the subsidiary cells.     

Epidermal Structure and Stomatal Ontogeny in Some Polygonales and Centrospermae

The epidermal structure and ontogeny of stomata in 19 speciesof Centrospermae and two of Polygonales are described. The cellsof the epidermis are polygonal, isodiametric, or elongated invarious directions and arranged irregularly. The anticlinalepidermal walls are thick, sinuous, straight, or arched. Eleventypes of glandular and eglandular trichomes have been observed.Six types of stomata: anomocytic, paracytic, stomata with asingle subsidiary cell, diacytic, anisocytic, and transitionalbetween diacytic and paracytic, have been noticed in the speciesinvestigated. The ontogeny of anomocytic stomata is haplocheilicor perigenous, while that of the other five types is syndetocheilicor mesogenous. Abnormal stomata with a single guard cell, unequalguard cells, aborted guard cells, and arrested development arecommon. Groups of stomata are also frequent but contiguous stomataare rather rare.     

Studies on Plasmodesmata in the Trichomes and Leaf Epidermis of some Asclepiadaceae

The occurrence of plasmodesmata has been studied in the trichomesand leaf epidermis of 12 species of the Asclepiadaceae. Plasmodesmataare observed in the walls of hair cells, epidermal cells, andstomatal apparatus. Plasmodesmata are present between adjacenthair cells from base to the apex; epidermal and basal hair cells;epidermal cells; epidermal and subsidiary cells; subsidiarycells, and subsidiary and guard cells, thus establishing mutualsymplasmatic contacts.