BIOLOGY Volume 1 - A Guide to General Biology - 2004

2. THE DIVERSITY OF LIFE ON EARTH

2.7. Kingdom Plantae

2.7.3. Seed plants

The most successful plant group produces seeds. These plants apparently evolved from extinct seed-bearing fern ancestors and their close relatives. The Taxonomy and Main characteristics of seed plants are summarized in Table 2.10.

Table 2.10 examines the two main groups of seed plants: gymnosperms and angiosperms. The latter are more commonly referred to as flowering plants. In gymnosperms, the ovules (and subsequently the seeds) lie exposed On the surface of specialized scale-like leaves known as megasporophylls or seed scales. These scales are aggregated into cones. In angiosperms, the ovules—and consequently the seeds—are enclosed within specialized structures, providing greater protection.

Class="center">Table 2.10. Taxonomy and main characteristics of seed plants

Seed plants

Main characteristics

The sporophyte is the dominant generation; the gametophyte is highly reduced

The sporophyte is heterosporous, producing Two Types of spores: microspores and megaspores; the microspore develops into a pollen grain, and the megaspore develops into the embryo sac

The embryo sac (megaspore) remains entirely enclosed within the ovule (megasporangium); the fertilized ovule constitutes a seed*

Water is not required for sexual reproduction, as the male Gametes are non-motile (with a few primitive exceptions); to fertilize the egg Cells, they reach the Ovary via a pollen tube*

Complex Vascular Tissues are present in roots, stems, and leaves

Division Coniferophyta (conifers)

Division Angiospermophyta (flowering plants)

Typically produce cones, which bear sporangia, spores, and seeds

Produce flowers, which bear sporangia, spores, and seeds*

Seeds are not enclosed in an ovary, but lie exposed on The surface of specialized leaves called seed scales,* which are aggregated into cones

Seeds are enclosed within an ovary*

Do not produce fruits, as they lack an ovary

Fruits develop from the ovary following Fertilization*

Classes: Dicotyledoneae and Monocotyledoneae (see Table 2.11)

* Diagnostic feature


Last update: 06/08/2026

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