“Gymnosperms are a group of plants that produce seeds not enclosed within the ovary or fruit.”
Gymnosperms belong to kingdom ‘Plantae‘ and sub-kingdom ‘Embryophyta’. The fossil evidence suggested that they originated during the Paleozoic era, about 390 million years ago.
Term Gymnosperm was Given by Theophrastus.
Gymnospermology:- Study of Gymnosperms
The Gymnosperms (Gymnos : naked, Sperma : Seeds) are plants in which the ovules are not enclosed by any ovary wall and remain exposed , both before and after fertilization. The seeds that develops post fertilization are not covered i.e., are naked.
In Gymnosperms embryo and seed formation takes place but no fruit formation occurs.
Gymnosperms includes medium-sized trees or tall trees and Shrubs.
One of the gymnosperms, the giant redwood tree Seqoia is one of the tallest tree species.
All gymnosperms are vascular plants. Therefore vascular tissue is present i.e., Xylem and Phloem.
Xylem lacks Vessels & Phloem lacks companion cells.
Exception- In Xylem of Gnetum, Ephedra, Welwitschia, True vessels are present.
The Roots are generally tap roots. Roots in some genera have fungal association in the form of mycorrhiza (Pinus) while in some others (Cycas) some specialized roots called Coralloid Roots are associated with N2- Fixing cyanobacteria.
The stems are unbranched ( Cycas) or Branched (Pinus, Cedrus).
The leaves may be simple or compound. In Cycas the Pinnate leaves persists for a few years. The Leaves in Gymnosperms are well adapted to withstand extremes of the temperature, humidity and wind. In conifers, the needle like leaves reduce the surface area. Their thick cuticle and sunken stomata also reduce water loss.
In the Vascular bundles, Cambium is present therefore secondary growth takes place in gymnosperms therefore they are considered woody Plants.
