Gymnosperms include three main classes :
- Cycadopsida (Cycads):
(a) Cycades constitute a small group of gymnosperms with palm like habit and fern like foliage.
(b) Cycades are mostly xerophytic and occur in warm regions.
© They are also grown as ornamental plants e.g.,Cycas.
(2) Coniferopsida (Conifers):
(a) Conifers are the dominant gymnosperms including more than 500 living species
(b) They are cone bearing plants with excurrent habit or conical canopy.
© They possess an aromatic, antiseptic semi fluid resin.
(d) Conifers mostly occur in colder region, e.g.,Pinus, Cedrus, Juniperus, Picea etc.
(3) Gnetopsida:
(a) This group includes climbing shrubs and small trees.
(b) Their xylem possess vessels.
© The reproduction organs are borne in whorls or inflorescence.