Variation among plants regenerated from cultured somatic cells; it can have genetic or epigenetic causes.

Retention of unfavorable linked material during introgression of a desired allele.

A controlled preparatory treatment that changes subsequent germination or stress responses; benefits and storage costs depend on the crop and treatment.

A member of the land-plant lineages comprising mosses, liverworts and hornworts. Their persistent gametophytes support attached sporophytes; physiological independence should not be inferred merely from a green sporophyte.

A land plant with the specialized conducting tissues xylem and phloem. An independent, usually conspicuous sporophyte supports transport and growth; the ecological requirements of the gametophyte still matter for completing reproduction.

An anchoring structure on relevant plant bodies. It may contribute to water or nutrient uptake, but is not anatomically identical to a root.

Capacity to survive substantial drying and recover function after rehydration. It differs from avoiding water loss. Recovery of one physiological signal does not establish successful growth and reproduction.

An orchid studied for chemical mimicry of its pollinator’s female sex pheromone.

Milkweed is a common name especially associated with flowering plants of the genus Asclepias. These plants are important hosts for monarch butterfly larvae, connecting plant chemistry, feeding specialization and interactions among species.

Mimulus is a genus name used in the monkeyflower literature. Some species historically placed in it are now treated in other genera, including Mimulus guttatus. Comparing experiments therefore requires tracking both the species identity and the name used by a source.

A plant completing its life cycle within one growing year; this does not imply that all varieties have identical flowering requirements.

A plant persisting for multiple years; repeated reproductive episodes and vegetative renewal create different allocation requirements from those of annual crops.

The African oil palm, Elaeis guineensis, is a tropical plant cultivated for oils from its fruits and seeds. Clonal propagation makes it an important example of the difference between matching genetic sequence and maintaining a normal developmental state.^[ref]

The tomato is the flowering plant Solanum lycopersicum and its fleshy fruit. It is useful for investigating fruit growth and ripening because changes in tissue structure, pigmentation and chemistry can be related across biological development.

Rice refers to cereal plants cultivated for their edible grain, especially Oryza sativa, and to the grain itself. In biological discussion, the species, cultivated population and harvested seed should be distinguished.

Bread wheat is the cereal plant Triticum aestivum. Its genome, shaped by polyploidy, contains related chromosome sets from different ancestral lineages, making it a useful example of the interaction between hybridization and polyploidy.

Arabis alpina is a perennial flowering plant used to investigate repeated seasonal flowering. Experiments on its PEP1 regulatory system connect responses to winter conditions with the maintenance of a perennial life cycle.^[ref]

The asthenosphere is a relatively weak region of the upper mantle below the mechanically strong lithosphere. A seismic low-velocity zone often occurs in this region, particularly beneath oceanic lithosphere, but mechanical weakness and seismic speed are distinct properties.

The acute angle between two unoriented planes is the acute angle between their nonzero normal vectors, giving the displayed formula. For an oriented convex polyhedron, the interior dihedral angle of a convex polyhedron is instead $\pi$ minus the angle between outward face normals. The distinction matters when a face normal is reversed: its unoriented plane is unchanged, but its vector angle is replaced by its supplement.