Seed

The seed is the ovule ripened, it contains the germ of the future plant, called the "embryo," the outer part of the seed is called the "testa," and the space between this and the embryo is generally filled with starchy matter called the "albumen." The embryo consists of the plumule or  stem, the "radicle" or root, and the cotyledons or leaves of the future plant; when the seed has but one cotyledon it is called "monocotyledonous" and when it has two "dicotyledonous."

Seed. 

Parts.Integuments, seed-coats. Nucleus, part containing the embryo.

(1.) Parts of Integuments :

Testa  (episperm ), the outer or proper seed-coat.

Tegmen  (endopleura ), the inner coat, sometimes wanting.

Funículus Hílum  (h ), Chalāza  (c ), Rhāphe  (r ), are the same as in ovule.

Aril, covering exterior to the integuments (not in the ovule) (May-apple, Water-lily).

Coma a tuft of hairs on certain seeds (Silkweed).
This is to be distinguished from pappus, which is a tuft on the fruit (Achenium).

(2.) Parts of Nucleus

Embryo  (e ), the initial plantlet.

Radicle  (r ),  the rudimentary stem or first internode.

Cotylēdon  (c ), the seed leaf at the primary node.

Plūmule  (p ), the growing points above the cotyledons.

Albūmen  (a ),  the food for the plantlet's first growth, stored outside the embryo.

Kinds.—(1.) General Form Orthotropouscampylótropousanátropous;amphítropous same as in ovule.

(2.) Form of Covering :

Conformed, adhering closely to nucleus.

Cellular, loose (Pyrola).

Winged having expanded appendages (Catalpa).

Woolly, covered closely with fibers (Cotton).

Cōmose with coma at the end (Willow Herb).

(3.) Texture of Albumen :

Farinaceous, mealy (Wheat).

Oily, mealy but mixed with oil (Poppy).

Muciláginous, like mucilage (Morning-glory).

Ruminated, wrinkled (Papaw).

(4.) Number of Cotyledons :

Monocotylédonous (Corn).

Dicotylédonous (Bean).

Polycotylédonous (Pine).

(5.) Position and Arrangement of Embryo:

Eccentric embryo on one side of albumen (Indian Corn).

Perípheric curved around albumen (Four-o'clock).

Accumbent applied to the cotyledons when the radicle is bent and lies along their edge (Water-cress).

Incumbent applied to the cotyledons when the radicle rests against the back of one of them (Shepherd's Purse).

Conduplicate applied to cotyledons that are incumbent and so folded as to embrace the radicle (Mustard).

(6.) The Direction of the Embryo as respects the Pericarp.

Ascending, pointing to the apex.

Descending, pointing to the base.

Centripetal, pointing to the axis.

Centrifugal, pointing to the sides.