Up Ragweed pith Primary pit fields Primary pit fields Wall, face view Nucleate cells Compact parenchyma Sclerenchyma Intercellular spaces Leaf, xs Chlorenchyma Shoot tip, ls Apical meristem Vascular cambium Secretory duct Resin canal Clusia duct Root cortex Leaf aerenchyma Air chambers Air chambers Aerenchyma, Acorus Stellate cells Epidermis Endodermis Phloem, ls Phloem, xs Transfer cells Bean cotyledon Acorn, starch Potato starch Ice plant cell Tannin cell Small cells
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Fig.
3.5-2. Transverse section of water lily petiole (Nymphaea).
The large round, empty-looking cells marked by Xs are sieve tube
members, similar to those shown in longitudinal section in Fig.
3.5-1. The small angular cells (three are indicated by arrows) that are almost filled with red contents are
companion cells, which control the metabolism of the sieve tube members.
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