SUMMARY
The population structure of 4 California Iridaea cordata (Turner) Bory populations was studied. Random sampling procedures were used to measure seasonal variations in standing crops, density and size‐class distribution of life history stages. The results describe aspects of the in situ life history; a prerequisite to realistically considering the distribution, ecology or life history expressions of an alga. Seasonal fluctuations in density occur only in the juvenile stage, which is initiated during the winter (November to January) predominantly from the basal perennial crusts. Both the gametangial and tetrasporangial stages are present throughout the year. The tetrasporangial stage is dominant in relation to the sexual stages in both density and biomass during most of the year, except spring when the new crop in just maturing and all stages are abundant. Density in nearly constant and observable changes in the populations are due to biomass fluctuations. Seasonal lows in biomass occur during the winter with the majority of thalli in the smaller size‐classes. Growth and maturation culminate in peak summer crops and dominance of the tetrasporangial stage, followed by autumnal senescence and die‐back in winter. Carrageenans analyzed from immature thalli showed a predominance of lambda‐type, previously determined as specific for tetrasporangial plants. This indirect evidence for the tetrasporangial nature of immature plants suggests that dominance of the diploid stage occurred prior to blade development and most likely at the spore level. Alternatively, field results indicate a major contribution and possible replacement of alternation of gametangial and tetrasporangial stage by thallus perennation and vegetative reproduction.
1975. Carrageenans of gametangial and tetrasporangial stages of lridaea cordam (Gigartinaceae). Can. J . Bot. 53: 23 15-23 18. Carrageenans from gametangial (male and female) and tetrasporangial plants of the red alga Iririaerz cordafcr were isolated, fractionated, and characterized on the basis oftheir anhydrogalactose and sulfate content and infrared spectra. As in the case of Cl~orzrlrrrs crisprrs the tetrasporangial plants yielded only A-carrageenan while the gametangial plants produced carrageenans of the K-type. The male plants yielded proportionately more KCI-insoluble ~xarrageenan than did the female. The infrared spectra of the various preparations from I . cordcrta were virtually indistinguishable from those of comparable fractions isolated from C . crispus.
MCCANDLESS, E. L., J. S. CRAIGIE et J. E. HANSEN. 1975. Carrageenans of gametangial and tetrasporangial stages oflridaea cordafrr (Gigartinaceae). Can. J . Bot. 53: 2315-23 18. Les carragheenanes des tetrasporophytes et des gametophytes miles et femelles de I'algue hidaerr cordata ont ete isolees, fractionnes et caracterisees selon leur contenu d'anhydrogalactose et de sulfate et par la spectroscopie infra-rouge.Comme chez I'algue Chorzclrlrs crisplrs, les tetrasporophytes ne donnent que des carraghennanes du type A et les gametophytes du type K. Les gametophytes msles donnent proportionnellement plus de carraghennanes du type K, insolubies dans KCI, que les gametophytes femelles. Les spectres infra-rouges des diverses preparations de carraghennanes, isolees de I . cordcrta, sont virtuellement indiscernables de ceux de Chondrrrs crisprts.
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