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Seed plants divide into gymnosperms and angiosperms. Gymnosperms include conifers, cycads, and ginkgos, typically forming cones. Angiosperms comprise over 90 percent of known plant species, including flowering plants and trees that produce fruits. Both groups share a sporophyte-dominated life cycle and produce seeds for reproduction.

Gymnosperm seeds are typically housed in cones or on scales exposed to air and animals. Angiosperm seeds develop within fruits that facilitate dispersal through multiple methods: animals may eat fruits and deposit seeds elsewhere, or fruits help seeds float, fly, or attach to animals. This adaptation gives angiosperms reproductive advantages in diverse environments.

Monocots and eudicots differ in cotyledon number—monocots have one, eudicots have two. Additional distinctions include root systems, vascular tissue arrangement, leaf vein patterns, and flower organ development. Monocots have scattered vascular tissue and parallel leaf veins, while eudicots have ring-like vascular tissue and netlike leaf veins. Flower organs develop in multiples of three in monocots versus four to five in eudicots.

Cotyledons are embryonic leaves that form part of the seed and emerge during germination. Gymnosperms typically have 8 to 20 or more cotyledons arranged in a whorl around the embryonic stem. Most angiosperms have either one or two cotyledons. This cotyledon number is a primary classification feature distinguishing monocots from eudicots from the initial seed stage.

Seed plants produce microscopic gametophytes forming haploid gametes. Female gametes, called ovules, are housed in protective structures like cones or ovaries. Male gametes, called pollen grains, form in separate structures and disperse via wind or animals to fertilize ovules. Once fertilized, these diploid structures develop into seeds containing nourishment for seedling growth.

Seed plants dominate terrestrial vegetation due to their numerous adaptations. Their sporophyte-dominated life cycle, protected gametophytes, and efficient seed dispersal mechanisms—through cones, fruits, wind, and animals—enable reproduction across diverse environments. These features, combined with varied root systems and vascular tissue arrangements in basic plant anatomy roots stems and leaves, provide competitive advantages over other plant groups.

Basal angiosperms include Amborella, water lilies, and star anise relatives, representing early divergences from ancestral angiosperms. Magnoliids form a separate group containing thousands of species including magnolias. Most flowering trees and legumes are eudicots. These classifications, based on genetic evidence, refine the traditional monocot-dicot system and reflect evolutionary relationships among angiosperms.