salient features of gnetum
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Explanation:
In this article we will discuss about Gnetum. After reading this article you will learn about: 1. Distribution of Gnetum 2. Habit of Gnetum 3. Anatomy 4. Reproduction 5. Relationships.
Contents:
Distribution of Gnetum
Habit of Gnetum
Anatomy of Gnetum
Reproduction of Gnetum
Relationships of Gnetum
1. Distribution of Gnetum:
Gnetum, represented by about 40 species is confined to the tropical and humid regions of the world. Nearly all species, except G. microcarpum, occur below an altitude of 1500 metres. Five species (Gnetum contractum, G. gnemon, G. montanum, G. ula and G. latifolium) have been reported from India (Fig. 13.1). Gnetum ula is the most commonly occurring species of India.
Map Showing Distribution of Different Species of Gnetum
According to Bhardwaj (1957) various species of Gnetum occur in India in the following regions:
Gnetumula:
It is a woody climber having branches with swollen nodes. It is found in Western Ghats near Khandala, forests of Kerala, Nilgiris, Godawari district of Andhra Pradesh and Orissa.
Gnetum contractum:
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A scandent shrub growing in Kerala, Nilgiri Hills and Coonoor in Tamil Nadu.
Gnetum gnemon:
A shrubby plant found in Assam (Naga-Hills, Golaghat and Sibsagar).
Gnetum montanum:
A climber with smooth, slender branches, swollen at the nodes. It is found in Assam, Sikkim and parts of Orissa.
Gnetum latifolium:
A climber found in Andaman and Nicobar Islands.
2. Habit of Gnetum:
Majority of the Gnetum species are climbers except a few shrubs and trees. G. trinerve is apparently parasitic. Two types of branches are present on the main stem of the plant, i.e. branches of limited growth and branches of unlimited growth. Each branch contains nodes and intemodes Stem of several species of Gnetum is articulated
Some of the characteristics common in both Gnetum and other gymnosperms are under mentioned:
Wood having tracheids with bordered pits.
No sieve tubes and companion cells are present.
Presence of naked ovules.
Absence of fruit formation because of the absence of ovary.
Anemophilous type of pollination