Seeds, Embryogenesis, Germination, and Roots – Vocabulary Flashcards

A collection of vocabulary-style flashcards covering seeds, embryogenesis, germination, and root biology from the notes.

Seed

A plant reproductive unit consisting of an embryo, a nutrient source (endosperm and/or cotyledon), and a protective seed coat; capable of dormancy and dispersal.

Embryogenesis

Development of the embryo from the zygote through stages such as globular, heart, and torpedo to a mature embryo.

Endosperm

Triploid nutritive tissue in seeds that supplies nutrients to the developing embryo (present in many seeds).

Cotyledon

Embryonic leaf; in eudicots there are two cotyledons, while in monocots a single cotyledon is typically reduced to a scutellum that transfers nutrients.

Seed coat

Protective outer covering formed from integuments; divided into testa (outer) and tegmen (inner).

Testa

Outer coat of the seed coat.

Tegmen

Inner coat of the seed coat.

Hilum

Scar on the seed marking the point of attachment to the funicle; related to where the seed connects to the ovule.

Micropyle

Pore in the seed coat where the pollen tube entered; a site related to water entry during germination.

Embryonic axis

The root–shoot axis of the embryo, from which the radicle (root) and plume (shoot) develop.

Plume

Young shoot containing the shoot apical meristem and leaf primordia.

Radicle

Embryonic root; usually the first part to emerge during germination.

Hypocotyl

Region of the embryonic axis between the cotyledon attachment and the radicle; often forms a hook in epigeous germination.

Epicotyl

Region of the embryonic axis above the cotyledon attachment; gives rise to the shoot.

Epigeous germination

Germination where the hypocotyl elongates and the cotyledons emerge above ground.

Hypogeous germination

Germination where the cotyledons stay underground and the epicotyl/hypocotyl structure grows in the soil.

Coleoptile

Protective sheath around the plume (shoot) in monocots.

Coleorhiza

Sheath protecting the radicle in monocots.

Scutellum

Single cotyledon in monocots with vascular connections to the embryo and endosperm.

Endospermic dicot

Dicot seed that retains endosperm at maturity to nourish the embryo.

Non-endospermic dicot

Dicot seed that lacks endosperm at maturity; nutrients are stored in the cotyledons.

Monocot

Flowering plant group with typically one cotyledon, scattered vascular pattern, and distinctive monocot seed features (e.g., coleoptile, coleorhiza, scutellum in some).

Eudicot

Flowering plant group with two cotyledons and typically net-like leaf venation; embryo includes two cotyledons.

Dormancy

A state in which seeds do not germinate even under favorable conditions, allowing timing of germination.

Physical dormancy

Dormancy due to impermeability of the seed coat to water or oxygen.

Chemical dormancy

Dormancy due to compounds in the seed coat that inhibit germination.

Physiological dormancy

Embryo requires specific environmental cues to complete maturation for germination.

Endodormancy

Internal biochemical or physiological conditions must be met before germination can begin.

Ecodormancy

Germination is blocked by unfavorable external environmental conditions.

Seed bank

Persistent seed reservoir in the soil; seeds can remain viable for years and germinate when conditions are right.

Germination

Resumption of embryo growth when favorable conditions are met, following imbibition and metabolic activation.

Imbibition

Initial water uptake by a dry seed to kick-start metabolism.

Enzyme activation

Activation of enzymes that drive metabolism during germination (e.g., breakdown of stored reserves).

Starch breakdown

Conversion of starch reserves into sugars to fuel growth during germination.

Taproot

Primary root that persists and grows vertically, with lateral roots branching off.

Fibrous root

Root system with many thin roots; the primary root often dies early and adventitious roots predominate.

Root cap

Protective cap at the tip of a growing root, shielding the apical meristem.

Apical meristem

Region at the tip of the root where cells divide to enable growth.

Root hairs

Ext extensions of epidermal cells that increase surface area for water and nutrient absorption.

Rhizobia

Nitrogen-fixing bacteria that form symbiotic associations with legume roots.

Mycorrhizal fungi

Fungi forming symbiotic associations with plant roots to enhance nutrient uptake.

Endocarp

Inner layer of the fruit wall surrounding the seed.

Integument

The outer layers of the ovule that develop into the seed coat (outer and inner layers: testa and tegmen).