Page 231 - Pharmacognosy 2 PG303

Pharmacognosy-2 (PG303) Level 2 Clinical Pharmacy-Pharm D

Senega root: A, a habit sketch; B, T.S. of a root at different
places: 1,normal; 2-5, with one to three abnormal medullary rays; C,
detailed T.S. a, abnormal m.r; b, side branch; c, cambium; k, keel; pd,
periderm; ph, phloem; m.r, medullary ray; r.s, root scar; s.t, sieve
tissue; s, stem base; .w, wrinkles; w.p, wood parernchyma; v, vessel.;
xy, xylem.

Microscopical Characters
Cork, is narrow, formed of 2-6 layers of tangentially elongated, yellowish

brown, thin walled cells. Cortex, of phelloderm, narrow, usually contains large
lacunae, and formed of 2-6 layers of isodiametric, tangentially elongated, collen-
chymatous parenchyma. Phloem, in parts, is wholly replaced by parenchyma but
abnormally developed in the keel region, consisting of radial rows of parenchyma,
small groups of sieve tissue, and traversed by medullary rays. Medullary rays are 1-
3 cells wide. Cambium is circular. Xylem, with the exception of the parenchyma
wedges, is wholly lignified, consisting mainly of tracheids, and short pitted vessels,
few fibrous tracheids, and thin walled fibers, the whole traversed by numerous
indistinct lignified medullary rays. Primary xylem is 2-arch. All parenchyma

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