The majority of the world's flora is categorized as vascular seed plants, also known as tracheophytes. Vascular refers to plants featuring specialized tissues used to conduct water. Biologists refer to plants that reproduce via seed production as spermatophytes. Considered an advanced species of plants, the vast majority of plants surrounding humans are vascular seed plants.
Seed-producing vascular plants are classified as either angiosperms or gymnosperms. Angiosperms produce flowers. Ninety percent of all plant species are angiosperms, according to Clinton Community College professor Michael Gregory. Seeds produced by angiosperms are covered by fruit that aids in the dispersal and germination of the seed. The ability to flower has led to the success of the angiosperm, most through the ability to attract pollinators.
Four phyla make up gymnosperms: cycads, gingko, gnetophytes and conifers. Gymnosperms produce naked seeds, meaning they are not encased in fruit. Conifers are the largest phylum of gymnosperms, including evergreen trees such as fir, cedar, pine, spruce and redwoods. Cones form holding the naked seeds.
Early vascular plants developed through cell division in the main body of the plant and did not feature stems, leaves or roots. During the Devonian period, approximately 380 million years ago, vascular plants evolved to allow cell division in other areas, producing the plant's periphery structure. According to the New World Encyclopedia, seeds developed in advanced vascular plants 360 million years ago.
A prime example of vascular seed plants are conifers, known to be the oldest and largest trees in the world. According to Gregory, the bristlecone pines in Nevada are over 4,500 years old.
According to DeAnza College biology professor Brian McCauley, vascular seed plants can live in any habitat that supports plant life. Angiosperms cover most of the earth's terrestrial habitats. They are well adapted to living and reproducing on dry land.
According to the University of California Museum of Paleontology, seed plants are among the most important organisms on Earth. The major products of seed plants are soils, forests and food. Familiar to most people, vascular seed plants produce food for most terrestrial animals, either directly or indirectly.
Vascular plants contain three major tissue systems: the ground tissue system, the vascular tissue system, and the dermal tissue system. The ground tissues consist of cells that aid in the storage, secretion and photosynthesis of the plant. The vascular system conducts water, minerals, hormones, amino acids and carbohydrates throughout the plant. The dermal tissue provides the protective covering of the plant. In general, vascular plants feature dermal tissues consisting of cutin, a waxy substance. Each individual system features unique, specialized cells.