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Echinate - bearing prickles or spines.
Echinocarpa - with spiny fruit. Also acanthocarpa.
Ellipsoid - a compressed or flattened sphere.
Elliptic, Elliptical - oblong with regular flattened ends.
Emarginate - with notched ends or tips.
Embryo - the new plant developing from the fertilised egg cell (zygote) in the fertilised seed.
Endemic - originating from and confined to a specific, usually small, geographic area.
Endosperm - mass of nutrient tissue formed within the embryo sac.
Entire - with a continuous margin without teeth, lobes or indentations.
Ephemeral - a plant that completes its life-cycle in a very short time.
Epicalyx - a group of bracts below the calyx, resembling a (second) calyx.
Epicarp - the outermost layer of the pericarp of a fruit.
Epicotyl - the main axis of the seed embryo just above the cotyledons and continuing into the developing stem of the seedling.
Epidermis - the thin outermost protective cell layer, usually taken to include the waxy water-impermeable material (cuticle) overlying the living cells.
Epigeal - growing with one or more leaves above the ground. Germinating with cotyledons above the ground.
Epigenous - on or developing or growing on the upper surface of a part such as a leaf
Epiphyte - a plant (or other organism) that grows on another for support, without drawing any nutrients from it. Hence: Adj. Epiphytic.
Epithet - a descriptive adjective used as a noun forming part of the binomial botanical name of a species. e.g. gracilis = slender
Erectocentrus - with an erect central spine.
Erinaceae - with a hedgehog-like appearance.
Erose - ragged, with irregular random indentations.
Escape - an exotic species spreading from cultivation and becoming established in natural habitats.
Estuarine - associated with estuaries or river mouths, usually in brackish conditions.
Ethnobotany - the study of the uses of plants by various human cultures.
Etiolate - leaves and/or stems that are unnaturally long, often with a change of colour from the natural shade of green to yellow or white, due to insufficient light.
Euphorbus - physician to King Juba II (ca. 50 BC- 19 AD) of Mauretania. King Juba was said, by Pliny the Elder (23-79 AD), to have named a plant (probably Euphorbia resinifera) that he discovered on Mount Atlas in Morocco as "Euphorbea" after his physician. This is generally considered to be the origin of the name of the genus Euphorbia. A variety E. regis-jubae of Euphorbia obtusifolia commemorates King Juba himself.
Evaporation - the process of conversion of a liquid into a vapour or gaseous form. This change of state absorbs energy- the latent heat of vaporisation.
Evergreen - remaining green and leafy throughout the winter or resting season.
Evolution - a process of selection originally described by Charles Darwin in "The Origin of Species", whereby organisms possessing one or more characteristics conferring increased fitness, tend to survive and proliferate more successfully than similar organisms without these features. Natural selection therefore occurs for organisms possessing these desirable characteristics, and their numbers increase disproportionately within the population. Evolution generally proceeds very slowly, by selection for very small differences in characteristics. However, occasional introduction of large beneficial (in terms of fitness) changes into the gene pool leads to punctuated evolution where major changes occur over relatively short times compared with the geological record. The Cactaceae appear to be a group of plants which have diversified relatively recently, with few, if any, authentic fossils.
Compare with creation.
Excrescence - an outgrowth or protrusion from the surface.
Exine - the outer layer of the pollen grain wall largely composed of the polysaccharide sporopollenin and resistant to attack by chemicals.
Exotic - introduced from another climate, country or region.
Exserted - of stamens or pistils exceeding the length of the tepals.
Extinct - of a species which has completely died out. Species can also become "extinct in the wild" but persist in botanical or other collections.
Extinction - the process leading to complete loss of a species.