robust multicellular stalk of 100– 200 μm. High-THC strains have larger glan-
dular heads {up to 119μm (Small and Naraine,2016b)}. The length of the stalk
is highly variable; some of the glands have shorter stalks, some appear to be
almost sessile. These glands are particularly abundant on bracts of pistillate
plants and become the most conspicuous feature of older bracts (Hammond and
Mahlberg 1977 ).- Capitate-sessile glandular trichome(Fig.5.3a, f, g): This is the most con-
spicuous type during early stages of bract development. It is mainly found in the
abaxial leaf surfaces, petioles and young stems. The gland consists of a large
globose head measuring about 30– 50 μm in diameter (Hammond and Mahlberg
1973 ). Although appearing as stalkless, these trichomes possess a very short
stalk of one-cell high but 2–4 cells thick (Dayanandan and Kaufman 1976 ). - Bulbous glandular trichome(Fig.5.3e): This is the smallest type of glandular
trichome found inC. sativa. These trichomes possess a 1-2-celled stalk and a
1-4-celled head. These trichomes vary in their sizes and are generally about 10–
20 μm in diameter and 15– 30 μm in height (Dayanandan and Kaufman 1976 ;
Hammond and Mahlberg 1973 ).
The capitate-stalked and capitate-sessile glandular trichomes are similar in all
respects except the former type trichomes have a massive, multi-cellular stalk. The
globular head in both types of glands is made up of eight cells developed from
epidermal initials. These cells form a cellular disc which is about 30μm in diameter
and about 15μm in height. Due to the accumulation of the resinous secretion
between the outer surface of the disc and the extended cuticular membrane, the
glandular head becomes spherical in shape.
5.3.2 Non-glandular Trichomes
These are unicellular covering trichomes found on stems, leaves, petioles, stipules,
bracts and tepals. The non-glandular trichomes are of the following two kinds:JFig. 5.3 Glandular and non-glandular trichomes inC. sativa[C- LM; all others SEM; A, B,
G- colorized SEM images].aPortion of bract displaying glandular and non-glandular trichomes;
b–dCapitate stalked glandular trichomes (note an‘eyespot’on the glandular head in imageB; the
glandular disc and cuticular membrane inc; and a slightly broken‘neck’of glandular head
showing 4-cell arrangement, in imaged);eA capitate stalked glandular trichome and two of the
bulbous glandular trichomes;fA group of capitate sessile glandular trichomes on a young leaf; a
sessile glandular trichome on abaxial leaf surface (note the presence of stomata);hMorphology of
conical cystolith trichomes on adaxial leaf surface;iCystolith trichomes in sectional view showing
large cystolith crystals.Ghglandular head,Gt-1capitate stalked glandular trichome,Gt-2capitate
sessile glandular trichome,Gt-3bulbous glandular trichome,Ngnon-glandular trichome,Nkneck,
Skstalk,Ststomata
5 Morpho-Anatomy of Marijuana (Cannabis sativaL.) 129