Practical Pharmacognosy Trichomes (Hairs)
Trichomes (Hairs)
-Extension
to the outside of the epidermal cells which my be very short and conical
(papillae) or long and protruding (trichomes)
- The
trichomes are either non-glandular (covering) or glandular with a stalk and
swollen head formed of one or more secreting cells. The secretion usually
Volatile oil or oleo-resin
types:-
Covering
trichomes (non-glandular hair)
Multicellular
formed
of more than one Cells
a- Simple or unbranched:
1) Uni seriate: one
row of cells
2) Biseriate: two rows each row of one or more cells
3) Multiseriate: many rows of cells
1)
Simple-branched: uniseriate
body ending in tow branches
2)
Stellate: radiating
unicellular hairs
3)
Peltate: very
short stalk surrounded by plate-like structure formed of very close or
laterally joined cells
4) Candelabra:
branched tree-like with unicellular axis from which arise
numerous unicellular branches of hairs, several being at each point
II- Glandular hairs:
1-
Unicellular: not
of common occurrence
2-
Multicellular: common
type consists of stalk and head
Multicellular type with:
a-
Uniseriate stalk:
1)
Unicellualr head:
Digitalis
(1 celled stalk), Belladonna (2-3 celled stalk), Hyoscyamus (1-celled head)
2)
Multicellualr head: Digitalis
(1 celled stalk, 2-celled head), Datura (1 or more celled- stalk and many
celled ovoid head), Labiatae (very short, 1-celled-stalk and 8 radiating celled
head)
b-
Biseriate stalk: and
biseriate head as compositae
c-
Multiseriate stalk:
and a head with one or more secreting cells
d Branched stalk the branches ending in 1-celled heads as in Hyoscyamus muticus
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