ECONOMIC IMPORTANCE OF PTERIDOPHYTES

 
ABSTRACT
Pteridophytes, including ferns and fern-allies, are the earliest of all the land plants which originated during the Silurian period and went on to become the dominant vegetation of earth’s surface during the Carboniferous period. They became the first ever group of plants on earth’s surface showing the presence of well-developed vascular system, thereby, playing an important link in the evolution from cryptogams (algae and bryophytes) to phanerogams (gymnosperms and angiosperms). Though they have largely been replaced by seed plants in the course of evolution, they continue to form an important part of vegetation today and can be found distributed in a wide range of habitats in the moist tropical and temperate forests in the world. The pteridophytes being moisture and shade loving plants congregate at places where humid and damp conditions prevail. Pteridophytes have been used by different tribal communities and folklore as a source of food, fibre, craft, decoration material and medicine. Being a group of lower plants and their restricted distribution, pteridophytes remain unattended and their useful aspects are largely ignored. This present study mainly focuses on the Economic importance of Pteridophytes. Their use in medicine for treatment of external injuries and wounds, use in ornamention, biofertilizers, food, phyto-remediation.
 
CHAPTER ONE
Introduction
Man has been using plants as a source of food, medicines and many other necessities of life since ancient times. Even to this day the primitive tribal societies that exist depend on the plant life in their surroundings. Though there were investigations of the edible economic values of the higher plants, especially the pteridophytes and angiosperms have been unfortunately ignored. Pteridophytes existing today represent ancient plant species which appeared about 300 million years ago in the late Devonian period (Fernandez et al., 2011).Pteridophytes including ferns and fern-allies are non-flowering, vascular and sporebearing plants. They form a conspicuous element of the earth’s vegetation and are important from evolutionary point of view as they show the evolution of vascular system and reflect the emergence of seed habit in an the plants. About 250 million years ago, they formed the dominant part of earth’s vegetation. But in present day flora, they have been largely replaced by the seed bearing plants. They grow luxuriantly in moist tropical and temperate forests and their occurrence in different eco-geographically threatened regions from sea level to the highest mountains are of much interest (Dixit, 2000).
The ferns and fern allies do not form a monophyletic group (Smith, et al. 2006) and pteridophyta as a taxonomic group is now regarded as made up of two classes, Lycopodiophyta (fern allies) and Pteridophyta (true ferns) ( Smith et al. 2006; WCMC, 1992). The Lycopodiophyta is represented by only five relict genera (Isoetes, Lycopodium, Phylloglossum, Selaginella and Stilites) (WCMC,1992).The Pteridophyta are much more diverse than the Lycopodiophyta, showing great range of form and cosmopolitan in distribution ( WCMC, 1992) Lycopodiophyta and Pteridophyta is a small group of about 12000 species (WCMC, 1992; Chapman, 2009), with some species gathered in the wild for food and medicine, and others cultivated as food and ornamental plants. The ferns are thought by most people to be quite useless members of the plant kingdom. The deleterious effects of rapid fern growth are well publicized, but their useful aspects are largely ignored. Ferns are distributed in all climate zones of the planet, but have a greater diversity in the tropics (Smith et al., 2006; Strasburger et al., 2003). Ferns show various economic values towards food, fodder indicators, biofertilizers and insect repellents (Ghosh et al., 2004). Ferns are used as medicines to cure diseases in various countries. In China alone, 401 kinds of pteridophytic medicines have been used for various ailments (Luo 1998).
Sarker et al. (2011) reported the medicinal uses of 30 pteridophytes of Tamil Nadu. They were used to treat various ailments viz., wound healing, body sickness, diarrhoea, skin problems, body pain, knee problem, cough, cold, fever, asthma, kidney problem, tonic, chronic disorders, several aches, hair growth, stomach problems, ulcer, sore throat, leprosy, ophthalmic, typhoid, urinary bladder and rheumatism. Khare and Kumar (2007) studied ethnobotany of five pteridophytes viz., Adiantum philippense, Diplazium esculentum, Helminthostachys zeylanica, Lygodium flexuosum and Ophiglossum reticulatum used by the Tharu tribe of Dudhwa National Park, Lakhimpur-Kheri (U.P). The information collected by Singh et al. (2001) reported that 14 common Pteridophytes were used by the local people of Manipur in various forms. Kirn and Kapathi (2001), observed ethnomedical uses of 19 pteridophytes of Jammu and Kashmir.
The previous work indicate that the medicinal plants specially the flowering plants are given the more importance in these contents, non-flowering plants particularly fern and fern allies are ignored by scientists. According to Pieroni (2001), evaluation of plant species used in different cultural contexts is necessary in order to infer cultural components related to food acceptance and phytochemical constituents that influence the popularity of edible plants. Plant resources have gained prominence in sub-Saharan Africa as a natural asset through which communities derive food, enabling particularly poor families to achieve self-sufficiency. Documentation of use patterns of pteridophytes across sub-Saharan Africa is of relevance in understanding the importance of this ancient plant group to livelihood strategies of different ethnic groups. This is particularly important for this ancient evolutionary lineage which could potentially become extinct if harvested non-sustainably.