Gymnosperms are embryo forming, vascular tissue containing plants.
These are usually evergreen trees, rarely shrubs and very rarely perennial herbs. Sequoia is one of the tallest trees.
Ginkgo is a living fossil.
The dominant stage in the life cycle is the sporophyte and divided into root, stem and leaf.
The root system is usually a taproot system.
Roots of some plants are associated with fungal mycelia and form Mycorrhizal roots (Pinus), while in others they are associated with Cyanobacteria like Nostoc and Anabaena as in Cycas.
The stem of gymnosperms can be branched (Pinus, Cedrus) or unbranched (Cycas).
Leaves can be simple as in Ginkgo and Gnetum or Pinnately compound as in Cycas.
Leaves persist for a few years and they are well adapted to withstand extremes temperature, humidity and wind.
In conifers like Pinus, the needle-like leaves with sunken stomata and thick cuticle reduce the surface area to minimize water loss (xerophytic adaptation).
Anatomically the stem has Eustele with conjoint, collateral and open vascular bundles.
Xylem usually lacks vessels and companion cells are absent in phloem.
Stem and root show secondary growth.
-
Pinus is monoecious. The male and female cones are present on the same plant.