Page 100 - PG 101-Course notes مذكرة النظري 24-25 with spec

Medicinal plants (PG 101) Level 1 Clinical Pharmacy-PharmD

The Vascular tissue:

▪ In the center, there is the main vascular bundle. The type of the V.B. of the leaf

is the same as that in the corresponding stem.
▪ The vascular tissue is formed of xylem and phloem arranged in strands; the

xylem is located above the phloem.
▪ The protoxylem is directed towards the upper epidermis.

 In Dicot :

o The large bundles is surrounded by several layers of parenchyma (sheath).
o Supporting tissues are of collenchyma cells located below the upper and lower
epidermis opposite to the bundles.

 In monocots:
o The bundle sheath may be parenchyma or sclerenchyma or thick walled
parenchyma.

o Supporting tissues are usually fibers (above and below the bundles).

Comparison between Dicot leaf and monocot leaf

Items Dicot leaf Monocot leaf

Stomata Dicot stomata type Monocot stomata

Epidermis Usually polygonal or Usually, elongated cells
polyhedral cells

Palisade and Present Absent
spongy

V. B. Open or bicollateral Closed collateral

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