Volume 90, Issue 2
April 1981, pages 91-182
pp 91-98 April 1981
Monthly counts, in plantations ofPinus patula at Kodaikanal in southern India, during 1977 and 1978, indicate that fruitbody production byAmanita muscaria, a fungus forming sheathing (ecto-) mycorrhizas, was influenced by (i) the current month’s rainfall and (ii) the age of the plantation.
Fruitbodies rarely appeared in the absence of rain. Average monthly numbers increased in rain-months from 11 to 320 per thousand trees when monthly rainfall increased from 40 to 640 mm.
During a period of 11 months (February/December 1978) numbers of fruitbodies per 1000 trees ranged fromc. 150 to 10800 in plantations 5 and 16 years old respectively.
After rainfall-thresholds for fruitbody production had been exceeded—they were less in old, than in young, plantations—young plantations, judged by the production ofA. muscaria fruitbodies, were more responsive to additional rainfall than older plantations.
pp 99-106 April 1981
The carpels of pearl millet (Pennisetum typhoides) are infected bySclerospora graminicola. Vegetative mycelium present in the diseased mother plant infects the carpel through the stalk of the spikelet. This process may or may not cause hypertrophy. Zoospores infect the carpel through the stimga and style, without inducing hypertrophy. Infection process leading to the establishment of downy mildew mycelium in the carpellary tissue and its implications are discussed.
pp 107-127 April 1981
Since much confusion exists on the identity and nomenclature in certain polygalas, a taxonomic revision of the genusPolygala L. of Andhra Pradesh, Kerala and Tamil Nadu has been attempted, based on the observations in the field and critical studies on the specimens represented in various herbaria. Illustrations of some important characters for each species have been provided for easy comparison and identification.
pp 129-136 April 1981
The present paper describes alterations in the structure of bark, wood and gum-resin canals ofCommiphora mukul in response to mechanical injury. The samples of bark collected after 15 minutes of injury showed signs of visible distortion or collapse of cell walls, specifically of the phloem cells near the gum-resin canals. The process of cell wall degradation gets intensified after 45 minutes of injury and the complete cell collapse is sometimes evident. The histology of healed bark reveals mass dissolution of cells at the site of injury. Several phloem parenchyma cells show structural similarity with the epithelial cells of gum-resin canals. The intercellular spaces show the presence of gum as well as resin droplets. The wall of epithelial cells facing the duct lumen disintegrates and the resultant product is released into the duct lumen. The vessels and axial parenchyma cells close to the site of injury are plugged with gum-resin content. The development of tylosis as a result of injury is also evident in some vessels.
pp 137-142 April 1981
Cellophane film overlying agar media enabled dark fruiting in two fungi (Phoma sp. andAscochyta pisi Lib.), fruiting in light on Czapek’s agar in two other fungi [Phoma sorghina (Sacc).] Boeremaet al andLeptosphaerulina crassiasca (Sechet) (Jackson and Bell)] and increased fruiting in all the four fungi. The fungal hyphae branched more profusely on cellophane. The role of cellophane in the induction of fruiting in these fungi is discussed.
pp 143-151 April 1981
The developmental changes occurring in the vascular cambium ofDelonix regia have been studied in different age group trees having different circumferential central axis. It has been found that the cambial cells undergo considerable variation both in their number and dimension with the growing age. The fusiform initials experience a linear expansion by local apical growth, while the ray initials undergo rapid multiplication. The former loses ability of apical expansion and the latter continues to multiply and occupy more area of the cambial cylinder with increasing age.
pp 153-162 April 1981
Foliar sclereids inLimonium Tour. exhibits diffuse, terminal or mixed patterns of distribution. A few instances have been focussed to place on record the importance of sclereids in any future taxonomic revision of this genus.
pp 163-168 April 1981
Detailed observations on the pollen morphology which includes size and shape of grains, nature of aperture, type of sculpturing and exine thickness have been made on seven taxa of Flacourtiaceae. These observations reveal the underlying similarity among the various genera considered here.
pp 169-175 April 1981
The two types of waters, i.e., freshwater and seawater differ in their total solids (salinity), ratio of monovalent to divalent cations, the amount of the predominant cations or anions, and the Ca/Mg ratio. The growth behaviour of four diatoms isolated from these habitats was studied in different concentrations of Na, Ca and Mg which were varied taking into account the salient features of both water types. Results indicate that the growth response of these diatoms show little relationship to the composition of either fresh or seawater. It is evident that the ecological category of a species cannot be determined merely on the basis of presence or absence of its growth in certain concentrations and ratios of major ions.
pp 177-182 April 1981
Ovule ontogeny and the structure of seed coat and fruit wall inDicoma tomentosa are described. Ovules are anatropous, unitegmic and tenuinucellate. Integument develops from a group of initials and it is dermal in origin. Ovary wall shows zonal differentiation, as an outer zone and inner zone. Zonal demarcation will be completely obliterated after fertilization. An air space around the endothelium, a common feature in the ovules of the Asteraceae, is absent. At early stage, the integument does not exhibit any demarcation of zones. As the seed develops tannin-like substance accumulates around the cells, fruit is ribbed and hairy. Pappus is plumose and found in two whoels.