The main characters of gymnosperms are as follows:
(a) All gymnosperms are perennial, growing as woody trees or bushy shrubs.
(b) Vascular tissues are arranged into vascular bundles.
(c) Gymnosperms are heterosporous, i.e., they produce two type of meiospores : Microspores and megaspores. Microspores are produced on the microsporangia and megaspores are produced on megasporangia. The megasporangia are integumented and are called ovules.
(d) Flowers are absent, however, microsporophylls and megasporophylls usually aggregrate to form distinct cones or strobili called male cones and female cones respectively.
(e) Ovules are borne on megasporophyll and have three layered integument with an opening called micropyle.
(f) Pollination is accomplished by wind.
(g) Fertilization is affected by pollen tube produced by the male gametophyte. It is called siphonogamy.
(h) A food laiden tissue called endosperm is produced in a seed. Seeds are naked i.e., without any seed coat.