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General characteristic features
• Most of the gymnosperms are evergreen woody trees or shrubs. Some are lianas (Gnetum)
• The plant body is sporophyte and is differentiated into root, stem and leaves.
• A well developed tap root system is present. Coralloid Roots of Cycas have symbiotic association with blue green algae. In Pinus the roots have mycorrhizae.
• The stem is aerial, erect and branched or unbranched (Cycas) with leaf scars.
• In conifers two types of branches namely branches of limited growth (Dwarf shoot) and Branches of unlimited growth (Long shoot) is present.
• Leaves are dimorphic, foliage and scale leaves are present. Foliage leaves are green, photosynthetic and borne on branches of limited growth. They show xerophytic features.
• The xylem consists of tracheids but in Gnetum and Ephedra Vessels are present.
• Secondary growth is present. The wood may be Manoxylic (Porous, soft, more parenchyma with wide medullary ray -Cycas) or Pycnoxylic (compact with narrow medullary ray-Pinus).
• They are heterosporous. The plant may be monoecious (Pinus) or dioecious (Cycas).
• Microsporangia and Megasporangia are produced on Microsporophyll and Megasporophyll respectively.
• Male and female cones are produced.
• Anemophilous pollination is present.
• Fertilization is siphonogamous and pollen tube helps in the transfer of male nuclei.
• Polyembryony (presence of many embryo) is Present. The naked ovule develops into seed. The endosperm is haploid and develop before fertilization.
• The life cycle shows alternation of generation. The sporophytic phase is dominant and gametophytic phase is highly reduced. The photograph of some of the Gymnosperms is given in Figure 2.38
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