Table 2.
Timing of vein initiation and xylem differentiation in developing leaves of C3 and C4 Flaveria species
| Vein development phase | Vein order | C3F. robusta† | C4F. bidentis‡ |
|---|---|---|---|
| Vein initiation | Central 1° vein | <0·5 (<− 2·0)* | <0·4 (<− 2·5)* |
| Lateral 1° veins | 2 (−0·8)** | 0·6 (−1·9) | |
| 2° veins | 1 (−0·9) | 1 (−1·3) | |
| 3° veins | 2 (−0·8) | 2 (−1·1) | |
| Minor veins | 4 (−0·5) | 4 (−0·9) | |
| FEVs | 5 (−0·4) | 4·5 (−0·8) | |
| Xylem differentiation | Central 1° vein | 1 (−0·9) | 0·6 (−1·9) |
| Major veins (1°, 2°) | 25 (0·4) | 18 (0·3) | |
| Minor veins (3° +) | 50 (1·0) | 35 (1·1) | |
| FEVs*** | 53 (1·3) | 45 (1·3) |
Vein initiation is first appearance of procambium in apical quarter of leaf. Xylem differentiation is presence of continuous xylem within a vein order throughout the leaf. Ontogeny of leaves is indicated in average length (mm; unbracketed numbers) and leaf plastochron units (LPI; numbers in parentheses).
† n = 39 for vein initiation, n = 83 for xylem differentiation.
‡ n = 51 for vein initiation, n = 123 for xylem differentiation.
FEV, freely ending veinlet. * Stage inferred but not directly observed. ** Lateral 1° veins observed in basal sectors of the leaf only. *** Does not include late-formed FEVs.