Fig. 11.

Two possibilities for morphological closure of a tubular structure through differential directional growth: irregular thickening or lobation. (A, B) End of a tube seen from above. (A) Tube open. (B) Tube partially closed by irregular thickening (arrows). (C, D) End of the tube seen from the side. (C) Tube open. (D) Tube partially closed by lobe formation (arrows). (E) Micropyle with lobed inner (i) and outer (o) integuments. Illicium floridanum (from Igersheim and Endress, 1997, Fig. 75). Scale bar: (E) = 0·1 mm.