shleshmataka :
Morphology:
Root - 5-12 cm long, 1-7 mm thick, oblique and gradually tapering, bearing a few
rootlets; external surface, dirty brown; fracture, short.
Stem - Glabrous, cylindrical, hairy, slightly branched; 10-17 cm long, 1-8 mm thick,
grooved and ribbed; basal region of branches greenish-brown, apical region dark green,
bearing a number of flowers; fracture, short.
Leaf - Simple, dark-green, smooth, alternate, opposite, exstipulate, 2.5-5 cm long,
1.8-3.6 cm broad, elliptical, lanceolate, obtuse or acutely toothed; shape and size
variable; petiole short; odour, slightly characteristic.
Histology:
Root - Mature root shows 4-5 layered cork, consisting of tabular, tangentially elongated,
thick-walled cells filled with reddish-brown contents; secondary cortex consists of a
wide zone of thin-walled, parenchymatous cells having a few resin ducts; secondary
phloem, a narrow zone, composed of sieve elements and phloem parenchyma, traversed
by phloem rays; xylem well-developed, composed of vessels, tracheids, fibres and xylem parenchyma, traversed by 1-5 seriate xylem rays; xylem vessels usually solitary
or 2-4 in groups with reticulate thickening; fibres aseptate and pointed.
Stem - Mature stem shows several bulges at places and consists of a single layered
epidermis, externally covered with a striated cuticle; a number of epidermal cells
elongate to form multicellular covering and T-shaped trichomes with 2-6 celled stalk;
cortex 3-5 layers of thin-walled, tangentially elongated parenchymatous cells, a few
filled with reddishbrown content, bulges show a few layers of collenchyma between
epidermis and parenzhymatous cortex; endodermis single layered, composed of barrelshaped cells; pericycle occurs in the form of groups of pericyclic fibres; phloem consists
of strands of sieve tubes, companion cells and phloem parenchyma; xylem consists of
vessel, parenchyma and fibres; xylem vessls show reticulate thickening; parenchyma in
abundance and paratracheal; fibres thick-walled, aseptate, short, with pointed ends;
medullary rays 2-11 cells wide; central portion occupied by pith composed of hexagonal
to polygonal, thin-walled parenchymatous cells; a few simple starch grains present in
cortical cells; cluster crystals of calcium oxalate occasionally found in pith.
Leaf -
Petiole - shows a somewhat circular outline with two lateral projections one on each
side; epidermis on both surfaces, covered externally with striated cuticle and have both
type of trichomes as described in case of stem, followed by 2-3 layers of collenchyma on
upper and lower side; stele composed of three collateral vascular bundles located in
centre, central one larger and lateral two smaller; ground tissue composed of thin-walled
parenchymatous cells, a few having oil globules and rosette crystals of calcium oxalate.
Midrib - shows similar structure as described in petiole except for 1 or 2 layers of
collenchymatous cells below both epidermis and a single vascular bundle in centre; oil
globules and rosette crystals of calcium oxalate present in a few cells of ground tissue.
Lamina - shows dorsiventral structure; epidermis single layered on either surface,
composed of thin-walled, tangentially elongated cells, covered externally with striated
cuticle; trichomes similar to those of stem; palisade single layered; spongy parenchyma
4-5 layered, loosely arranged cells; vascular bundles embedded in spongy parenchyma;
rosette crystals of calcium oxalate and oil globules present in this region; anomocytic
stomata present on both surfaces.
