Glossary for Gardeners – E

Glossary for Gardeners

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ecology
The science of relationships between organisms and their environment.

economic threshold
The level at which pest damage justifies the cost of control. In home gardening, the threshold may be aesthetic rather than economic.

egg
A female sex cell.

emasculate
To remove a flower’s anthers.

embryo
The dormant, immature plant within a seed, the “germ” referred to in wheat germ.

embryo culture
See tissue culture.

enation
Epidermal outgrowths on leaves or stems.

endodermis
A layer of cells in roots between the cortex and the vascular tissues.

endosperm
The nutritive tissue within the seed of a flowering plant. Surrounds and is absorbed by the embryo.

enzyme
A biological catalyst that aids in a specific biochemical process, such as converting food from one form to another.

epidermal hair
A filament of cells arising from an epidermal cell.

epidermis
The outermost layer of cells covering a plant’s leaves, roots, and young parts.

epigeous germination
Seed germination in which the cotyledons are raised above the soil surface.

epinasty
An abnormal downward-curving growth or movement of a leaf, leaf part, or stem.

epiphyte
A plant growing on another plant for support.

espalier
The training of a tree or shrub to grow flat on a trellis or wall. Espalier patterns may be very precise and formal or more natural and informal.

etiolation
Development of yellow, long, spindly growth on a plant as a result of insufficient light.

ethylene
A gaseous plant hormone (C2H4) produced in abundance by ripening fruits and damaged tissues.

etiolation
The condition where a plant is grown in darkness, resulting in pale and elongated stems and underdeveloped leaves.

evergreen
A plant that never loses all of its foliage at the same time.

excise
To remove or extract, as an embryo from a seed or ovule.

excurrent
A tree form in which the main trunk remains dominant with small, more or less horizontal branches. Fir and sweetgum are examples.

exfoliating
Peeling off in shards or thin layers, as in bark from a tree.

exoskeleton
The outer support structure of an insect.

exotic
Non-native.