Читать книгу The Circle of Knowledge: A Classified, Simplified, Visualized Book of Answers - Various - Страница 240

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: Orthotropous, ; campylótropous, ; anátropous, ; 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.