Kotiledonok

Kotiledonok (plural of *kotyledon*) refers to the embryonic leaf structures found in the seeds of seed plants, including gymnosperms and angiosperms. These structures play a crucial role in the early development of seedlings and are key features distinguishing different plant groups. In botanical terminology, *kotyledon* derives from the Greek words *kotyletēs*, meaning "cup-shaped," reflecting their often cup-like appearance in some species.

In monocots (monocotyledons), such as grasses and lilies, seedlings typically develop a single cotyledon, known as a *scutellum* in cereals. This single structure aids in nutrient absorption from the endosperm, the seed’s stored food supply. In contrast, dicots (dicotyledons), including beans, sunflowers, and oaks, produce two cotyledons. These cotyledons may remain underground (hypogeal germination) or emerge above the soil (epigeal germination), depending on the species. The cotyledons often serve as the primary site for photosynthesis and nutrient storage during early germination.

The presence and number of cotyledons are important taxonomic markers. For instance, the classification of plants into monocots and dicots historically relied heavily on cotyledon count, though modern phylogenetics has refined these categories. Some primitive seed plants, like cycads and ginkgo, also exhibit cotyledons, though their structure and function may differ from those in flowering plants.

Cotyledons are transient structures, typically absorbed or transformed as the seedling matures. Their role in seedling establishment highlights their significance in plant ecology and evolution, as they facilitate the transition from a dormant seed to an independent photosynthetic organism.