Anisophylly is when leaves of a pair differ from one another, either in size or in shape. When a horizontal stem (plagiotropic shoot) also exhibits anisophylly, the photosynthetic leaf surfaces interfere less with light from above, and rotation of the leaf or the petiole can enhance that effect. The phenomenon is relatively common in some tropical plant families with
decussate
Decussation is used in biological contexts to describe a crossing (due to the shape of the Roman numeral for ten, an uppercase 'X' (), ). In Latin anatomical terms, the form is used, e.g. .
Similarly, the anatomical term chiasma is named aft ...
leaf arrangement, such as
Melastomataceae
Melastomataceae () is a family of dicotyledonous flowering plants found mostly in the tropics (two-thirds of the genera are from the New World tropics) comprising c. 175 genera and c. 5115 known species. Melastomes are annual or perennial herbs ...
,
Gesneriaceae
Gesneriaceae, the gesneriad family, is a family (biology), family of flowering plants consisting of about 152 genera and ca. 3,540 species in the tropics and subtropics of the Old World (almost all Didymocarpoideae) and the New World (most Ges ...
and
Urticaceae
The Urticaceae are a family, the nettle family, of flowering plants. The family name comes from the genus ''Urtica''. The Urticaceae include a number of well-known and useful plants, including nettles in the genus ''Urtica'', ramie (''Boehmeria ...
as well as in certain species of other families.
References
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Plant morphology
Leaves