dextrorse

Dextrorse is an adjective meaning turned to the right, derived from Latin dextro- “to the right” and the suffix -orse. It is used to describe right-handed spirals, coils, or orientations in biology and related fields. The corresponding opposite term is sinistrorse, which denotes a left-handed or counterclockwise spiral when viewed from a specified vantage.

In zoology and malacology, dextrorse commonly describes the direction of shell coiling in snails and other mollusks. Most snail shells coil dextrally, so the aperture appears on the right side when the shell is held with the apex upward and the opening facing the observer. Sinistral shells coil to the left and are less common. Some species, such as Amphidromus perversus, exhibit both dextral and sinistral individuals within the same population.

In botany, dextrorse is used to describe clockwise spirals in certain inflorescences or arrangements of floral parts and leaves, though sinistrorse denotes counterclockwise spirals. The terms help describe phyllotaxis and the handedness of spiral patterns in plants.

In mechanics and crystallography, dextral can refer to right-handed helices or screw-like structures, such as dextral (right-handed) screw threads that tighten when turned clockwise. The opposite, sinistral, refers to left-handed helices or threads.

It is important to distinguish dextrorse from dextrorotatory: the latter describes the rotation of plane-polarized light to the right (optical activity), whereas dextrorse concerns spatial handedness of spirals and coils.