A LIVING HAZARD: BRACKEN FERN
[Pteridium aquilinum (L.)Kuhn]
INTRODUCTION
With their large, shiny green and highly dissected leaves, ferns are so visually appealing and many of them are sold as ornamentals. But certain fern species can create substantial problems and they are herein called “problem ferns”. Pteridium aquilinum (bracken fern) is one of the problem ferns which cause the greatest range of problems on ecology and human welfare. Bracken fern has been described as one of the five most common plants on earth, the most locally intensive and globally extensive. It is a ubiquitous fern belonging to the phylum Pteridophyta and to the family Dennstaedtiaceae.
In India it is found on exposed grassy lands in hills. It is an ornamental, tufted, fast growing …show more content…
All fronds are potentially fertile; there is no morphological distinction between infertile and fertile fronds. Spores are minute. They are borne in sporangia which congregate in a continuous line along the undersurface margins of the pinnae (Parsons, 1961; Krochmal, 1973). There is an indefinite or rudimentary inner indusium which is further covered by the false indusium. The false indusium is the leaf margin rolled back over the marginal sori. Sporulation is influenced by a complex of factors, including: age of plant, genotype, developmental stage of fronds, seasonal weather conditions and site environmental factors such as exposure, shade and wind (Wynn et al. 2000). Spores can be released suddenly through the drying of the annulus, and they may be dispersed by wind and water. Spores germinate without a period of dormancy. If sown within a week of collection they can show up to 95% germination within 5 days. Spores stored in a dry place may retain their viability for several years although they often take longer to germinate and prothallus development may be sluggish. Spore generation seems to require soil sterilized by fire (Chavez and Gill,
[Pteridium aquilinum (L.)Kuhn]
INTRODUCTION
With their large, shiny green and highly dissected leaves, ferns are so visually appealing and many of them are sold as ornamentals. But certain fern species can create substantial problems and they are herein called “problem ferns”. Pteridium aquilinum (bracken fern) is one of the problem ferns which cause the greatest range of problems on ecology and human welfare. Bracken fern has been described as one of the five most common plants on earth, the most locally intensive and globally extensive. It is a ubiquitous fern belonging to the phylum Pteridophyta and to the family Dennstaedtiaceae.
In India it is found on exposed grassy lands in hills. It is an ornamental, tufted, fast growing …show more content…
All fronds are potentially fertile; there is no morphological distinction between infertile and fertile fronds. Spores are minute. They are borne in sporangia which congregate in a continuous line along the undersurface margins of the pinnae (Parsons, 1961; Krochmal, 1973). There is an indefinite or rudimentary inner indusium which is further covered by the false indusium. The false indusium is the leaf margin rolled back over the marginal sori. Sporulation is influenced by a complex of factors, including: age of plant, genotype, developmental stage of fronds, seasonal weather conditions and site environmental factors such as exposure, shade and wind (Wynn et al. 2000). Spores can be released suddenly through the drying of the annulus, and they may be dispersed by wind and water. Spores germinate without a period of dormancy. If sown within a week of collection they can show up to 95% germination within 5 days. Spores stored in a dry place may retain their viability for several years although they often take longer to germinate and prothallus development may be sluggish. Spore generation seems to require soil sterilized by fire (Chavez and Gill,