Bryophytes are small, non-vascular plants that contain chlorophyll and reproduce sexually. They have a dominant gametophyte stage and lack true roots, stems, and leaves. Bryophytes are divided into three divisions: liverworts, which have undifferentiated leaves and store oils; hornworts, distinguished by their horn-like sporophytes; and mosses, which have single-cell wide leaves and can absorb large amounts of water. Bryophytes require external water and are considered amphibians of the plant kingdom.