sieve tubes that are not lignified and always
connected to companion cells (Grosser and
Liese 1971). Sieve pores aligned with small
callose platelets connect the sieve tubes. The
companion cells are characterized by dense
cytoplasm and a large nucleus (Liese, 1998). In
G. angustifolia, the phloem is formed by 14 to
25 sieve tubes (Fig. 4). According to Liese and
Weiner (1996), a bamboo culm might have a