Orientation of Paired Leaves in Grapevines and Related Species
| Species | Total leaf pairs examined | Pairs with opposite-side | Pairs with same-side | Ratio (n to 1) |
|---|---|---|---|---|
| Vitis vulpina | 155 | 108 | 47 | 2.30 |
| Vitis labrusca | 383 | 287 | 96 | 2.99 |
| Vitis coignetiae | 58 | 37 | 21 | 1.76 |
| Vitis riparia | 843 | 646 | 197 | 3.28 |
Many plants have leaves that are larger on one side of their long central axis than the other, a phenomenon known as asymmetrical orientation. University of California, Berkeley biologist Ciera Martinez and colleagues examined several species of grapevines and closely related plants, which have leaves that grow in pairs, to see if both leaves in a pair tend to be oriented toward the same side (that is, have more tissue on the same side) or not. They found that opposite-side orientations are more common than same-side orientations by ratios as high as .