Figure 4

Longitudinal view of stems of Yiduxylon trilobum gen. et sp. nov. from Hubei. (a) Tangential section showing leaf traces (upper two arrows), sclerenchyma cells (lowermost arrow) and parenchyma cells of cortex. HY5-2. (b) Tangential section showing sclerenchyma (arrow) and parenchyma cells of cortex, and secondary xylem (far right). HY2-3. (c) Tangential section of secondary xylem showing multiseriate pitting on tangential wall of tracheids. HY7-2. (d) Radial section of secondary xylem showing rays (arrows) and pitting on radial walls of tracheids. HY4-3. (e) Tangential section of secondary xylem showing high and mainly biseriate rays. Note pitting on tangential walls of tracheids. HY9-2. (f-k) SEM observation of secondary xylem. (f) Secondary xylem in radial fracture showing very high rays. (g) Radial fracture showing rays and tracheids. Note pitting on radial walls of tracheids. (h) Radial fracture showing rays and underlying tracheids. (i) Enlargement of (h) showing ray cells and tracheids with pits. (j) Enlargement of (i) showing bordered pits of a tracheid. (k) Bordered pits of a tracheid. Scale bars = 1 mm (a), 0.5 mm (f), 0.2 mm (b, d, e, g), 0.1 mm (c, h), 50 μm (i), 10 μm (j, k).