Fig. 8.

Relation between stem morphology, anatomy and leaf orthostichies in U. uniloba. (A) Stem in the field showing lobes and furrows, and nodes in front of the furrows. (B) Schematic image showing relation between lobed stems and orthostichies. (I, II) Stem in early developmental stages with nearly homogeneous rates of vascular tissue (~2–5 mm in diameter) (III, IV) Lobed stems (~12–22 mm in diameter). (V) Split stem with phloem wedges in the lobes (~22 mm in diameter). (VI) Stem ~22 mm in diameter. Note that lobes split (black arrowhead) under the node (white arrowhead). (VII–X) Note that the furrows (white arrowheads) are the weakness zone between lobes (black arrowheads), where the stem eventually splits into different portions.