FIGURE 4 in Plant structure ontology: How should we label plant structures with doubtful or mixed identities? *

FIGURE 4. Developmental aspects of submerged plant parts (lacking roots) of Utricularia foliosa (Lentibulariaceae). A, B. Growing watershoot tips with conspicuously curved indeterminate shoot apical meristems (SAM). The meristematic tips of the lobes, which continue to divide, are less curved than the SAM of the watershoots. Sessile two-celled hairs are visible on the convex and concave sides of the young watershoots. 1–5 = "leaves" = outgrowths along watershoot flank, each one dividing to form two determinate lobes. X = inflorescence primordium. Scale bars = 50 µm (A) and 100 µm (B). C. Determinate ends of leaf tip (arrowhead) and primary leaflet tips. The curved tips elongate considerably by precocious differentiation before ceasing growth. Scale bar = 500 µm. D. Racemose inflorescence apex forming bract (B) primordia, with floral apices (arrowhead) in their axils. Note presence of slightly curved tips of leaf primordia (L). Scale bar = 100 µm. Fig. 4A modified from Sattler & Rutishauser (1990).