Cotyledon
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A cotyledon is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or more of which are the first t
Cotyledon from a Judas-tree (Cercis siliquastrum, a dicot) seedling
Comparison of a monocot and dicot sprouting. The visible part of the monocot plant (left) is actually the first true leaf produced from the meristem; the cotyledon itself remains within the seed.
Peanut seeds split in half, showing the embryos with cotyledons and primordial root
Two-week-old Douglas fir (a conifer) with seven cotyledons
Acorn
Videos
The acorn is the nut of the oaks and their close relatives; alternatively known as glans. It usually contains a seedling surrounded by two cotyledons, enclosed in a tough shell known as the pericarp,
Cotyledon
…remaining below ground and not becoming photosynthetic. The latter is typically the case where the cotyledons act as a storage organ, as in many nuts and acorns. Hypogeal plants have (on average) significantly larger seeds than epigeal ones. They are also capable of surviving if the seedling is clipped off, as…
English oak acorn
Acorns of the willow oak in South Carolina (from small to large, counterclockwise from center): Q. phellos (willow oak), Q. falcata (southern red oak; top right), Q. alba (white oak), and Q. coccinea (scarlet oak). Scale bar at upper right is 1 cm.
Diagram of the anatomy of an acorn: A.) Cupule B.) Pericarp (fruit wall) C.) Seed coat (testa) D.) Cotyledons (2) E.) Plumule F.) Radicle G.) Remains of style. Together D., E., and F. make up the embryo.
Horses eating acorns. Acorns can cause painful death in equines, especially if eaten in excess.