The zygote is produced by the process of syngamy and the other male gamete fuses with the secondary nucleus to form the triploid Primary Endosperm Nucleus (PEN). In angiosperms, the astrological nature of the endosperm is triploid (3n). In the triploid condition, each nucleus has three' sets of chromosomes.

a- Flowers b- carpel c- stamen d- seeds

In gymnosperms, pollination is carried out by wind.Flowers in angiosperms have showy petals, nectaries, scent glands and several other devices to attract the insects, birds and other animals including man to help them to get pollinated.

microsporophyll of gymnosperms  It is broad and not distinguished into filament and anther.
microsporophyll of angiosperms It consists of a filament and a terminal anther.

Gymnosperms and angiosperms are classified separately although they both bear seed because of following reasons
i) Ovules in gymnosperms are naked. In angiosperms, they are enclosed inside the ovary.
ii) Wood is non-porous in gymnosperms,i.e, the vessels are absent. Wood in angiosperms is porous,i.e, the vessels are present.

Bryophytes are terrestrial plants. But, they need water for completion of their life cycle. External water is required for dehiscences of antheridia, liberation of antherozoids, transfer of antherozoids from antheridia to archegonia, etc. Rest other stages of life cycle are terrestrial, so they are called amphibians of plant kingdom.

Vascular tissues i.e., xylem and phloem are absent in bryophytes. The conduction of water and food takes place from cell to cell by diffusion.

Bryophyta belongs to the class - Anthocerotopsida
The sporophyte which is cylindrical like a horn hence, the Anthoceros is called as hornwort.

Chemotaxonomy or biochemical taxonomy is based on the protein and serum analysis and on the chemical constituents of the organisms. This type of taxonomy is particularly utilized in the classification of plants, as chemical constituents of plant species are stable and do not change easily.

The artificial system of classification was mainly based on vegetative characters or on the androcium structure (system given by Linnaeus). Such system separated the closely related species since they were based on a few characteristics. The artificial system gives equal weight to vegetative and sexual characteristics. This is not convincing because the vegetative characters are more easily affected by the environment.