Blossoming Evolution: The Remarkable Story of Angiosperms

Angiosperms emerged approximately 125 million years ago and underwent rapid diversification due to climatic changes 25 million years later. Since then, they have stood out as the most dominant and recognizable seed plants, surpassing their counterparts, the gymnosperms, which include conifer evergreens. Contrary to previous theories, angiosperms are believed to have evolved independently from gymnosperms. They exhibit superior adaptability, thriving in diverse soils and climates. In contrast to gymnosperms, angiosperms boast a more efficient reproductive mechanism with seeds sheltered within fruits and pollination facilitated by insects and other animals, ensuring more effective seed dispersal. Eudicots, formerly known as dicots, make up around three-quarters of angiosperms and encompass a wide array of flowering plants, including carnations, roses, tobacco, legumes, potatoes, grains, maples, and sycamores.

Comprising 90 percent of the plant kingdom with approximately 250,000 species, angiosperms rank second only to insects in terms of diversity. They exhibit an array of sizes, shapes, colors, scents, and arrangements, attributes that have led to specialized partnerships with mutualistic pollinators, showcasing a classic case of co-evolution between distinct organisms. In contrast, wind-pollinated flowers lack colorful features.

Angiosperm flowers, aside from their aesthetic appeal, serve as efficient and unique reproductive systems. They often house both male and female reproductive structures within the same flower. Gametes are produced in separate flower organs, allowing for internal fertilization and embryo development, offering protection against inclement weather. Stamen produces pollen containing sperm, while the pistil generates the ovule. Pollen adheres to a receptive surface on the pistil, germinates, and delivers sperm to the ovule via the pollen tube, culminating in fertilization. Surrounding tissues thicken as the embryo develops into seeds within a fruit. Fruits, like pollen and seeds, are dispersed by wind and consumed by animals. The seeds pass through the digestive tract intact, facilitating their deposition in new locations.

These two Iranian earthenware tile panels, dating from the first half of the nineteenth century, feature depictions of a fraction of the over 250,000 species of angiosperms, the flowering plants.