The plant kingdom is divided into two main groups: vascular and non-vascular plants. Vascular plants have tissues that transport water and nutrients throughout the plant. Non-vascular plants like mosses and liverworts lack these tissues and rely on cell walls for transport. Seedless plants reproduce via spores and include non-vascular bryophytes as well as vascular horsetails, ferns, and spikemosses. Seed plants have true roots, stems, leaves and vascular tissues. They reproduce via seeds and are divided into gymnosperms like conifers, which have naked seeds, and angiosperms, which produce flowers and fruits containing seeds. Angiosperms are further divided into monocots and dicots.