Seed plants---or spermatophytes, as they are technically termed---are plants that reproduce via seeds from either flowers or ovules. Seed plants can be subdivided into five major plant types, including flowering plants and conifers. While there are millions of types of seed plants throughout the world, all seed plants share three main characteristics---vascular tissue, seed reproduction and common plant body parts---across all subgroups.
Vascular tissue is the system developed by plants for both physical support and the delivery of nutrients to plant cells for growth and seed development. The cells within the plant's vascular tissue create thick, firm walls that support the shape and form of the plants. The vascular tissue is also the carrier for the essential nutrients and material for building new plant cells, including water-soluble nutrients and moisture.
Types of Vascular Tisssue
The vascular tissue in seed-bearing plants can be categorized into two separate types. The first type, xylem, carries water-soluble nutrients and moisture absorbed by the plant's underground or surface root network. The second type, phloem, is the vascular tissue that carries the nutrients created through photosynthesis in the plant's stems and leaves. This creates a tissue network through which nutrients are constantly moving in both directions.
All seed plants reproduce via seed production. Seeds are essentially a dormant plant covered in a protective coating. The outer coating is called a seed coat. Encased in the coat is a plant embryo---created by the fertilization of a plant egg with plant sperm---and stored enzymes and nutrients that become activated in the right conditions to feed the new plant. The seeds are dispersed from the mature seed plant through various methods, including via wind, water and by carrier animals like birds.
All seed-producing plants share major body parts, including a root network, stems and leaves that grow from the stem. The size of these parts vary extensively by plant species, but are present in some shape or form in all spermatophytes.