Definition - What does Lateral Sinus mean?
The lateral sinus is an anatomical part of the grape leaf which includes the two deep notches located between the lateral lobes and basal lobes. It includes the two lobes between the apical lobe and lateral lobe and is similar to the web of tissue between our fingers.
The shape and depth of the lateral sinus can help identify what variety a grapevine is.
WineFrog explains Lateral Sinus
Ampelography is the field of botany that is mainly concerned with the identification and classification of grapevines. Outside of DNA testing, well-trained ampelographers can identify grape varietals by looking at the anatomical shape and structure of grape leaves.
One of the main parts they look at is the shape of the lateral sinus. The identification is narrowed down by looking at its shape, its depth and the lack of or presence of "teeth" (Is the edge of the leaf jagged or smooth?).
In order to identify the grape varietal, they narrow it down by also looking at:
- The presence of hair - Is it woolly or bristly, or is there no hair?
- Lobe number
- Size and shape of the teeth - Are they convex, pointed or concave?
- The shape of the petiolar sinus
- The overall leaf shape
- Is the leaf color light or dark?
- The leaf surface - Is it rough, smooth or "bullate"?
- The color of the petiole and veins
- The contour of the leaf