An example of simile in scientific writing (about Habenaria chlorantha / Large Butterfly Orchis):
"The drum-like pedicel is of the highest importance, not only by rendering the viscid disc more prominent and more likely to stick to the face of an insect whilst inserting its proboscis into the nectary beneath the stigma, but on account of its power of contraction.
… But observe what takes place: in a few seconds after the inner end of the drum-like pedicel is removed from its imbedded position and exposed to the air, one side of the drum contracts, and this contraction draws the thick end of the pollinium inwards, so that the caudicle and the viscid surface of the disc are no longer parallel, as they were at first…. At the same time the drum rotates through nearly a quarter of a circle, and this moves the caudicle downwards, like the hand of a clock, depressing the thick end of the pollinium or mass of pollen-grains."
Charles Darwin (1862) On the various contrivances by which British and foreign orchids are fertilised by insects, and on the good effects of intercrossing. London: John Murray
Darwin describes the pedicel as drum-like, but later shifts to metaphor ("one side of the drum", "the drum rotates"). A second simile is used to describe how the rotation of the drum was like "like the hand of a clock".
Read about examples of science similes
