FIGURE 1 in Plant structure ontology: How should we label plant structures with doubtful or mixed identities? *

FIGURE 1. "Leaves" with mixed identities. A. Compound foliage leaf of ash (Fraxinus excelsior: Oleaceae) infected with the gall mite, Aceria fraxinivora (Nalepa, 1909). Unlike typical ash leaves, this leaf is partially doubly pinnate and lacks a terminal leaflet. The leaf tip is occupied by a bud (arrow), which strongly resembles buds found on shoots. X = stem, Y = leaf rachis. B – D. Indotristicha ramosissima (Podostemaceae). B. Drawing of a portion of a long shoot with lateral ramuli: ca. 3 cm long determinate, feather-like appendages in the positions where leaves normally occur. Similar to typical leaves, most ramuli subtend axillary shoots. Scales are found as lateral stem appendages, especially towards the shoot tips. Stars = tips of axillary shoots, each subtended by ramulus. C. Apical region of a ramulus at a young developmental stage (250 µm long). The apical meristem (RP) is elongated and slightly curved. Most of the globular primordia on flank of the apex will grow into linear, bifid scales. Scale bar = 30 µm. D. Cross-section of a ramulus tip with the apical meristem in the centre (RP) surrounded by linear scales consisting of a single cell layer. Scale bar = 100 µm. C, D modified from Rutishauser & Huber (1991).