Volume 88, Issue 5
September 1979, pages 331-412
pp 331-345 September 1979
A resume on the morphological features of tracheoids has been presented under various typological heads with examples drawn from the published literature to enhance their utility in detailed descriptions of tracheoids. Depending on the constancy of cell form the tracheoids are classified under two groupings: homomorphic and heteromorphic. Homomorphic group includes brachytracheoids, sclerotracheoids, macrotracheoids, tubuliform spirotracheoids, vermiform tracheoids and loratotracheoids. Heteromorphic grouping includes heterotracheoids. Each type represents a descriptive unit recognised on the cell form and is supported by a qualifying description for their delimitation.
pp 347-357 September 1979
Trichomes of fifteen species ofVernonia occurring in South India have been studied to evaluate their interrelationships. Eighteen types of trichomes have been described. Trichome complements of these taxa are variable in their structure and organographic distribution. On the basis of the latter, occurrence of biotypes inVernonia albicans and varieties inVernonia monosis andVernonia peninsularis is visualised. Examination of paired affinity indexes of the trichome complements of lower leaf surfaces indicates thatV. albicans andV. cinerea;V. monosis andV. shevaroyensis andV. indica andV. comorinensis are closely related.
pp 359-365 September 1979
The spore concentration of 40,000 spores/ml is essential to produce disease consistently on all the leaves of five week-old plants excepting the top leaf. With increase in age of the plants, susceptibility toA. triticina increased. The intensity of disease decreased from base to top of the plants. In a resistant variety, only small specks appeared on the leaves. The pathogen entered the leaf generally by direct penetration and rarely through stomata. Germ tubes were restricted to the epidermal and occasionally to the subepidermal layer of the resistant variety.
pp 367-372 September 1979
Stigeoclonium tenue Kütz., a chief inhabitant of metal polluted waters, was studied in culture to understand its tolerance towards certain metals such as copper, manganese, mercury, silver and zinc. This study was carried out also with two other chemicals DDT and CaOCl2. The alga was inhibited by very low concentrations of HgCl2, AgNO3 and DDT while it tolerated high levels of other metals and CaOCl2.
pp 373-378 September 1979
Metabolism of sulphur amino acids and free amino acids has been studied in the cotyledons during germination ofAlbizzia lebbeck Benth seeds under different light intensities. Seeds ofA. lebbeck contain a large amount of sulphur amino acids which are rapidly utilised during early stages of germination A similarity in the distribution pattern of amino acids in cotyledon samples raised from different seed stocks is noticed. The level of amino acids was higher in the illuminated samples as compared to dark controls. The higher concentration of asparagine, and SAAII during the seedling growth with the increase in light intensities compared to dark-grown seedlings as well as initial seed sample may indicate the involvement of light-triggered reactions in the synthesis of these metabolites.
pp 379-390 September 1979
The vascular anatomy of the flower of 18 species of Bignoniaceae is described. The flowers are hermaphrodite, zygomorphic, hypogynous and pentamerous. In many investigated taxa several medullary traces are given from the central vascular cylinder. The calyx shows much variation in its vascular supply in different taxa of the family. It is suggested that one-trace condition of the sepals has arisen by the fusion of the laterals with the median and multitraced condition by amplification of the three traces. Each petal receives a single trace but inTecomaria capensis although there are four petals, five traces differentiate for the corolla. The posterior petal which has two traces seems to have arisen by the incorporation of two petals. A siphonostelic stamen trace has been observed in some taxa and it has been correlated with the large size of the filaments. The vascular supply of each carpel consists of a dorsal bundle, a ventral strand and several carpellary laterals. The Bignoniaceae show an intermediate condition between axile and parietal placentation. The disc is very richly vascularised and derives its vascular supply from more than one source. It is suggested as carpellary in nature.
pp 391-395 September 1979
Trichomes of nine species belonging to four genera have been studied. Organographic distribution of each type is given. Ontogeny of one more type has been worked out.
pp 397-400 September 1979
In all the three plants selected, viz.,Pongamia, Diospyros andArgeria there appears to be a specific reduction in riboflavin (B2), niacin, protein, protein nitrogen, soluble nitrogen and total nitrogen contents of gall tissues, thus perhaps indicating that the insect larvae may preferentially feed on these nutrients of the leaf. There also appears to be a general reduction in reducing sugar content although it is not so significant. Increased starch content is noticed inPongamia.
pp 401-406 September 1979
There is a marked change in the structure and dimensions of the shootab apex during a plastochron. The plastochronic changes are described in three phases: pre-leaf initiation, leaf initiation and post-leaf initiation. There is a cup-shaped cambium-like zone developed for a short duration during a plastochron. The origin of the axillary bud is from the peripheral meristem of the main shoot apex and its early development is due to the anticlinal divisions in tunica cells and multiplane divisions and growth in the corpus cells. There are two bud traces, in the form of residual meristem, for an early bud meristem. The procambialisation occurs acropetally.
pp 407-412 September 1979
Analysis of pigment composition by TLC were carried out during aGymnodinium (bloom) in Brahmsarovar Tank. During the experimental period considerable changes occurred in the absolute and relative amounts of the various pigments, especially of β-carotene, diadinoxanthine, chlorophyll-C, and chlorophyll-a. The ratio of total carotenoids to total chlorophyll reached a maximum during the peak of theGymnodinium bloom. Significant changes occurred in pigment composition in natural phytoplankton while the species composition remained constant.