Hint: The two major groups of vascular seed plants are angiosperms and gymnosperms. Angiosperms, or flowering plants, are the kingdom of Plantae's largest and most diverse group. Gymnosperm seeds are typically formed in unisexual cones known as strobili, and the plants do not produce fruits or flowers.
• Angiosperms: Angiosperm, any of approximately 300,000 species of flowering plants, the kingdom Plantae's largest and most diverse group. Angiosperms account for roughly 80% of all currently known green plants.
Angiosperms are vascular seed plants in which the ovule (egg) develops into a seed in an enclosed hollow ovary. The ovary is usually enclosed in a flower, which is the part of an angiosperm that contains the male or female reproductive organs, or both.
• Gymnosperms: Gymnosperms are plants that produce seeds that are not contained within an ovary or a fruit. Pollination directly fertilizes the seeds because they are open to the air.
“Gymnosperms,” from the Greek gymnos, “naked,” and Sperma, “seed,” develop their seeds on the surface of scales and leaves, which often grow to form cone or stalk shapes, differing from angiosperms in characteristics.
• Both angiosperms and gymnosperms are seed-bearing plants that share some characteristics. Siphonogamy is the process by which male gametes are transferred to female gametes via the pollen tube in plants. This phenomenon occurs in both angiosperms and gymnosperms.
Note: Angiosperms include monocots such as lilies, orchids, agaves (known for agave nectar), and grasses, as well as dicots such as roses, peas, sunflowers, oaks, and maples. Non-flowering evergreen trees such as pine, spruce, and fir are examples of gymnosperms.