The plant is first classified according to some physical characteristics.

The plant is first classified according to some physical characteristics, usually the flowers and fruit. This arrangement and classification of organisms is called taxonomy.
The table below shows a summary of the classification of part of the plant kingdom. Most of the plants of interest to gardeners are Spermatophytes or seed-bearers.

SPERMATOPHYTES (seed-bearing plants) / \ GYMNOSPERMS (ovules not enclosed in an ovary) eg. Cycads, Conifers ANGIOSPERMS (ovules enclosed in an ovary) Flowering plants | / \ | | | | | | | | | DICOTYLEDONS Seedling - two cotyledons present Flower-parts, eg. petals in 4's or 5's Herbaceous or woody stems with vascular bundles forming a ring usually broad leaves with branching veins usually a taproot with lateral roots MONOCOTYLEDONS Seedling - one cotyledon present Flower-parts, eg. petals or stamens in 3's or 6's Usually herbaceous stems with vascular bundles throughout usually narrow leaves with parallel veins fibrous roots, arising from base of stem | | | ORDER ORDER ORDER | | l FAMILY eg. Taxaceae FAMILY eg. Rosaceae FAMILY eg. Iridaceae | | | GENUS eg. Taxus GENUS eg. Prunus GENUS eg. Iris | | | SPECIES eg. baccata SPECIES eg. lucitanica SPECIES eg. sibirica

The seed are produced from ovules which are enclosed - Angiosperms, or naked - Gymnosperms.
The Angiosperms are divided into Dicotyledons which have a split seed producing two seed-leaves (cotyledons), and Monocotyledons which produce one seed-leaf. Other similarities of the two are given above. They are all further subdivided into Orders, Families, Genera and Species.
Families, eg. Rosaceae - the Rose family, contain many Genera which are similar in structure, eg. the Genus Prunus.