Page 118 - Pharmacognosy 2 PG303

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

THYMUS HERB

The dried leaves and flowering tops of Thymus
vulgaris Linne Family: Labiatae (Lamiaceae)

Macroscopical Characters
The drug has an agreeable aromatic odor and pungent
aromatic taste. The stem is quadrangular, grayish- brown to
purplish and hairy. The leaves are very small, grayish- green,
opposite decussate, sessile, or shortly petiolate, linear
lanceolate to ovate with grayish hairy surfaces, acute apex and
entire revolute margin. The flowers are very small, purple,
zygomorphic, shortely pedicellate and arranged in terminal
verticillasters. Calyx is tubular has a ring of stiff hairs in the
throat. Corolla is purple and bilabiate. Androecium is formed
of 4 didynamous stamens, stigma bifid.

Microscopical Characters
The leaf is dorsiventral with double layered palisade
cells. Both upper and lower epidermal cells have wavy anticlinal walls and are covered with
striated cuticle. The upper epidermis bears diacytic stomata, orange- red labiaceous and conical
unicellular non- glandular trichomes. The lower epidermis has wavy anticlinal walls, abundant
stomata and shows labiaceous glandular and 2- 3 celled uniseriate non- glandular trichomes. The
non- glandular trichomes often bent near the base, sharply- pointed apex and have papillosed or
coarsely warty cuticle. Capitate hairs are few and are abundant on the lower epidermises. Calcium
oxalate crystals are absent. The stem is square in T.S. shows epidermal cells with few stomata,
numerous 3- celled warty non-glandular trichomes, bent at right angle near the base and few
labiaceous trichomes. Cortex is formed of collenchyma followed by parenchyma and pericycle
consists of groups of lignified fibers. The calyx shows several long pointed, 6- 8 celled uniseriate
non- glandular trichomes with one or two collapsed cells. Pollen grains are spheroidal and smooth.

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