A
seedling is a young plant
sporophyte developing out of a plant embryo from a
seed. Seedling development starts with
germination of the seed. A typical young seedling consists of three main parts: the
radicle (embryonic root), the
hypocotyl (embryonic shoot), and the
cotyledons (seed leaves). The two classes of
flowering plants (angiosperms) are distinguished by their numbers of seed leaves:
monocotyledons (monocots) have one blade-shaped cotyledon, whereas
dicotyledons (dicots) possess two round cotyledons.
Gymnosperms are more varied. For example,
pine seedlings have up to eight cotyledons. The seedlings of some flowering plants have no cotyledons at all. These are said to be
acotyledons.
