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. 2015 Mar 23;168(1):357–376. doi: 10.1104/pp.114.255711

Figure 1.

Figure 1.

Description of anatomic structures of hesperidium. A to D, Anatomic structures of four citrus varieties: Satsuma mandarin (A), Ponkan mandarin (B), sweet orange (C), and Shatian pummelo (D). Bars = 30 mm. E and F, Appearance of the flesh-rind anatomic structure of loose-skin Satsuma (E) and tight-skin sweet orange (F). Bars = 10 mm. G and H, Detailed anatomical structures of an orange fruit. G, Hesperidium fruit has two major distinct regions, rind (1) and flesh. The flesh comprises segment epidermis (2) and juice vesicles (3). Bar = 20 mm. H, Light microscopy image of orange fruit rind. The rind comprises a series of parts: epidermis (4), flavedo area (5), oil gland (6), albedo area (7), and lignin dye with phloroglucinol-HCl (8). Bar = 0.25 mm. Hesperidium fruits have two distinct tissues: flesh (endocarp or pulp) and rind (pericarp or peel). The flesh is the edible part of most citrus fruits, including juice vesicles with segment membranes and vascular bundles. The rind is further divided into two parts: flavedo (exocarp) is the external chromoplast-rich colored layer, and albedo (mesocarp) is the white layer characterized by numerous intercellular air spaces.