Plants are widely distributed and are essential to the survival of many other species. Plants are classified by presence or absence of vessels and seeds. Bryophytes lack vessels. Vascular plants have vessels and may be seedless or produce seeds.
Gymnosperms have naked seeds, and angiosperms have covered seeds.
Bryophytes are small green plants lacking vascular tissue, supportive tissue, and true leaves and stems. They resemble the earliest plants, which arose from algae. Bryophytes reproduce both asexually and sexually. The gametophyte is dominant, and sexual reproduction requires water for sperm to travel through. Sperm from an antheridium travel to eggs in an archegonium.