Compact Growth Form Research Articles

Population dynamics of a tropical intertidal and deep-water population of Sargassum polyceratium (Phaeophyceae)

Plant numbers, plant size, number and length of primary laterals, reproduction, growth rates and turnover rates were recorded for an intertidal and a deep-water (30 m depth) population of Sargassum polyceratium Montagne at Curaçao, Netherlands Antilles, for 1.5 years. Both populations showed distinct seasonal variations in biomass and growth rates, with maxima in late summer-early autumn and minima in winter. The observed fluctuations were probably amplified by a severe autumn storm that significantly reduced biomass in both populations at the end of the first year. The main differences between the populations were a more compact growth form and higher growth rates and turnover rates of primary laterals in the intertidal population.

‘Dakota Sunrise’ Cinquefoil1

AbstractShrubby cinquefoil (Potentilla fruticosa L.) is native in scattered areas of North America and Asia. Many cultivars have been selected for ornamental uses, especially for foundation or border plantings. The popularity of cinquefoil is based on its compact growth form, hardiness and abundant flowers produced throughout the summer. The drought tolerance and winter-hardiness of ‘Dakota Sunrise’ makes it a promising cinquefoil for the Northern Great Plains.

Growth Forms in Arctostaphylos glauca

Arctostaphylos glauca has evolved two growth forms in the San Bernardino Mountains of Southern California. A chaparral ecotype of upright shrubs with relatively long leaves occurs in chaparral on the south and west sides of the mountain range. A desert woodland ecotype of low, compact, spreading shrubs with shorter leaves occurs in pinyon woodland on the north and northeast sides of the same range. The chaparral ecotype flowers early and fruits heavily. Upon periodic destruction by fire its populations are replaced by numerous seedlings. The woodland ecotype flowers late and fruits sparingly. Its lower seed reproductive potential is further indicated by the lower total number of floral units, by a lower proportion of fruit set, and by an apparent truncation of the flowering season before all the flower buds open. An alternative strategy, involving long life, compact growth form, and the exploitation of new soil resources by layering and vegetative reproduction in the absence of regular fire recycling has evidently adapted an old chaparral plant to recent desert woodland conditions.

GROWTH FORMS IN ARCTOSTAPHYLOS GLAUCA

Arctostaphylos glauca has evolved two growth forms in the San Bernardino Mountains of Southern California. A chaparral ecotype of upright shrubs with relatively long leaves occurs in chaparral on the south and west sides of the mountain range. A desert woodland ecotype of low, compact, spreading shrubs with shorter leaves occurs in pinyon woodland on the north and northeast sides of the same range. The chaparral ecotype flowers early and fruits heavily. Upon periodic destruction by fire its populations are replaced by numerous seedlings. The woodland ecotype flowers late and fruits sparingly. Its lower seed reproductive potential is further indicated by the lower total number of floral units, by a lower proportion of fruit set, and by an apparent truncation of the flowering season before all the flower buds open. An alternative strategy, involving long life, compact growth form, and the exploitation of new soil resources by layering and vegetative reproduction in the absence of regular fire recycling has evidently adapted an old chaparral plant to recent desert woodland conditions.

Variation within naturally occurring Townsville stylo (Stylosanthes humilis) population; changes in population structure and some agronomic implications

Two populations of Townsville stylo collected from Townsville (T) (rainfall 1140 mm) and from Greenvale (G) (rainfall 640 mm) were grown in small swards at four locations (rainfall 460-869 mm) for 2 years. Phenotypic variation in the original populations and the T-derived populations from seven of the eight location-year combinations was assessed in a pot experiment. Numerical analysis of the data using an agglomerative classification delineated five distinct growth forms. The proportions of these forms differed in the original T and G populations, and the population structure of the T plots changed markedly towards that of the original G population after only one growing season at the four locations. These changes could be related to environmental conditions and weed competition. It is suggested that population heterogeneity may represent an adaptation to varying ecological and climatic conditions. Heterogeneous seed mixtures may therefore be agronomically superior to individual genotypes, and compact growth forms with high seed indices may be more suited to harsher environmental conditions.

Pseudocompact-type growth and conversion of growth types of strains of Staphylococcus aureus in vitro and in vivo.

Some strains of Staphylococcus aureus grew as compact colonies in Brain Heart Infusion-serum-soft agar but as diffuse colonies in a modified Staphylococcus 110-serum-soft agar. These strains were designated "pseudocompact." Strains showing compact-type colonial morphology in both media were designated "compact," whereas strains showing diffuse-type growth in both media were designated "diffuse." It was observed that the most recently isolated strains of S. aureus were of the pseudocompact type, whereas most stock culture strains tested were of the compact type. Using cultures recently isolated from clinical material, it was shown that pseudocompact strains convert to compact-type growth after prolonged incubation. Interconversion of compact, diffuse, and pseudocompact growth forms could be induced in vitro by appropriate cultural conditions, and conversion of growth type was also observed in vivo. Femoral abscesses produced in mice by four different compact-type strains showed conversion to diffuse or pseudocompact-type growth during the course of the infection.