Seed plants are divided into two main groups: "angiosperms and gymnosperms". Gymnosperms are plants whose seeds are not enclosed in an ovary or fruit. Examples of gymnosperms include conifers, cycads, and ginkgos. Angiosperms, on the other hand, are plants whose seeds are enclosed in an ovary or fruit. This group includes most of the plants that people are familiar with, such as flowers, trees, and grasses. Angiosperms are further divided into two main subgroups: "monocotyledons and dicotyledons". These subgroups are based on the number of cotyledons (embryonic leaves) present in the plant's seed. Monocots have one cotyledon, while dicots have two. The division of seed plants into these groups is based on their morphology, anatomy, and reproductive characteristics.