Page 147 - Pharmacognosy-I (02-06-06-102)

The primary phloem, is formed of collapsed sieve tubes called
ceratenchyma.
The secondary phloem, is composed of phloem parenchyma, containing
axially elongated secretion cells containing volatile oil and mucilage.
The cells are thin-walled and contains starch grains not exceeding 10  in
diameter (D.F. cassia) and acicular crystals of Ca ox.

Phloem fibres : Occur isolated or in tangential rows, and more

abundant towards the inner part of the bark not more than 30  wide
(D.F. cassia). The fibres are strongly thickened lignified walls and very
narrow lumen. The medullary rays are usually biseriate formed of
radially elongated thin-walled cells widened slightly near the pericycle,
and containing numerous acicular crystals of Ca ox.

T. S. in Cinnamon bark

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