noun, plural: seed leaves
(botany) The primary or rudimentary leaf of the embryo of a seed plant that either remains in the seed or emerges upon seed germination; a modified leaf that is part of the plant embryo within the seed; a seed leaf.
In plants, the seed leaf is involved in the storage or absorption of food reserves. In some plants, the seed leaf may remain below the ground when the seed germinates. In other plants, the seed leaf exists in pairs and may show above the ground to perform photosynthesis, a function similar to a true leaf. The difference between the seed leaf and the true leaf is that the seed leaf develops at the embryonic stage while the true leaf develops post-embryonic stage.
Word origin: Latin cotylēdōn, navelwort, from Greek kotulēdōn, from kotulē, hollow object