Volume 87, Issue 2
February 1978, pages 1-74
pp 1- February 1978 Erratum
pp 1-15 February 1978
Cyclotella meneghiniana, when grown under different salinity regimes, shows varying rates of size reduction which is directly proportional to the salinity of the medium and is always greater for large than for small cells. The differential flexibility of the girdle band is responsible for differences in size reduction. Cells of dia 7·5–3·0μ are elongated on the pervalvar axis. The elongation is maximum in Reimann medium and decreased with increasing salinities and is brought about by the formation of new intercalary bandsC. meneghiniana maintains an internal osmotic pressure in excess of the surrounding medium and this ability helps in its survival in an environment of fluctuating salinities.
pp 17-22 February 1978
In the progeny of desynaptic diploids, one desynaptic tetroploid is obtained. A comparative study of the PMC meiosis in the desynaptic diploids and the desynaptic tetraploid is carried out. The desynaptic tetraploid is characterised by high univalent and low multivalent frequency. The mean chiasma frequency in the desynaptic tetraploid is only slightly higher than that in normal diploid plants and nearly twice the maximum frequency observed for the desynaptic diploids. Different possibilities for the origin of the desynaptic tetraploid and its genetic constitution are discussed.
pp 23-27 February 1978
Olacaceae,Ximenia americana L.—Embryology. Anther tapetum glandular. Endothecium fibrous. Cytokinesis in microsporocytes simultaneous. Pollen dimorphic, two-celled. Ovules ategmic, crassinucellar. Embryo sac Polygonum type, produces a haustorial caecum. A comparison with earlier investigations presented.
pp 29-35 February 1978
In one of the plants of the inbred line IP 1475 ofPennisetum americanum (L.) Leeke, spontaneous chromosome breakage was observed. Distribution of the breaks was non-random and was confined to the centromeres and to the chromosome ends. Breakage in the centric region was twice as frequent as that in the end segments. Further, nucleolar chromosomes were involved less frequently than others in breakage and stickiness. Other meiotic abnormalities like asynapsis, exaggeration and stretching of the centromere, chromosome stickiness and neocentric activity were also observed in the same plant. All these abnormalities were interpreted to be the features of breakdown of the genetic system resulting from the enforced inbreeding of the normally cross pollinated species.
pp 37-48 February 1978
The roots ofDecalepis hamiltonii Wt. and Arn. are used in South India as a substitute for the well-known Ayurvedic drug ‘Sariva’ (Hemidesmus indicus (L.) R.Br.) which has well-established therapeutic properties. The pharmacognostical details of the roots ofD. hamiltonii with illustrations and its comparison with the roots ofH. indicus which may be useful for distinguishing the two crude drugs are presented in this paper.
pp 49-53 February 1978
Limnocharis flava is a freshwater weed introduced on the Kerala coast in 1960 and now spread over a vast area extending over 300 km. It has a very efficient seed dispersal mechanism which is described. In addition, the morphology of the carpel, fruit and seed are described. It is concluded that the effective reproductory mechanisms makeL. flava a potentially dangerous weed.
pp 55-64 February 1978
The floral anatomy ofSwietenia mahogoni Jacq.,Soymida febrifuga Juss.,Chukrassia valutino A. Juss.,Dysoxylum binectariferum Hook.,Aphanamixis rohituka W. & A. andHeynea trijuga Roxb. are discussed. Calyx is supplied by two whorls of traces inSwietenia, Aphanamixis, Chukrassia andHeynea and only one whorl of traces inSoymida andDysoxylum. In all the species, exceptHeynea, petals receive their supply independently. InHeynea petals receive their supply from compound strands. Staminal tube receives its supply from compound strands inSwietenia,Chukrassia, Heynea, Aphanamixis and from independent strands inSoymida andDysoxylum. Anthers are syngenesious inDysoxylum.
Ovary is supplied only by carpellary ventrals inSoymida, carpellary ventrale and ovary wall traces inSwietenia, carpellary ventrals, ovary wall traces and carpellary dorsals inChukrassia and carpellary ventrals, ovary wall traces, carpellary dorsals and secondary marginals inAphanamixis, Dysoxylum andHeynea. Disc is considered receptacular. Ovary is 2–5 locular at the base but becomes unilocular above. InChukrassia it remains tetralocular throughout. Ovules show attachment to axile placentae inChukrassia, Heynea andAphanamixis and to parietal placentae inHeynea,Soymida, Dysoxylum andSwietenia. Non-vascular, 8–20 teeth-like structures are formed from staminal tube. These are interpreted as fused or interpetiolar stipules.
pp 65-70 February 1978
Pollen variability was studied using acetolysis technique in colchiploids raised inCrotalaria pallida yar.pallida (syn.C. brownei),C. juncea, C. refusa andC. sericea. The results obtained showed a great range of variability in various characters including size and shape of pollen, nature of colpus, exine surface ornamentation and os. The grains of all colchiploids were mainly 4-zonocolporate in contrast to 3-zonocolporate condition, in the diploids.
Pollen variability was also studied in a population ofCrotalaria raised after mutagenic treatments with gamma rays, EMS and dES. The pollens were mainly 1–4 colporate, asymmetric and nonfixiform (bipolar and radiosymmetric in control) with variable shapes and having distinct and clear reticulation. Micropollens were 1-spiraperturate.
pp 71-74 February 1978
The floral anatomy ofCyrtandromoea differs from those of the other taxa of Gesneriaceae in several respects but shows many resemblances with that of Scrophulariaceae. Hence the transfer ofCyrtandromoea from Gesneriaceae to Scrophulariaceae is supported.