5.1 Introduction
The genusCannabisL. belongs to theflowering plant family Cannabaceae. There is
controversy in the number of species in the genusCannabis. Some authors consider
that the genus is polyspecific, consisting of two to three species namelyC. sativa,
C. indicaandC. ruderaliswhile some others have recognized different varieties
within the speciesC. sativa, such as var.mexicana, var.Americana, var.sativaand
var.indica. However, the majority of authors regard the genus as representing only
one highly polymorphic speciesC. sativaL. (Bouquet 1950 ; Gilmore et al. 2003 ;
Klimko 1980 ; Miller 1970 ; Small 1975 ; Small and Cronquist 1976 ; Wu et al.
2003 ). The latter monotypic species concept is followed in the present work.
Cannabis sativa(Fig.5.1) is widely considered to be indigenous to Central Asia,
confined to an area that stretches from Turkestan in the west, to Pakistan in the east,
and from South China in the north to the Himalayas in the south (Wills 1998 ).
Being one of the earliest domesticated plants in the history of mankind, and with
long history of cultivation, the original distribution ofC. sativais unclear (Wu et al.
2003 ).
5.2 Morphology
The plants ofCannabis sativaare erect, annual herbs, which are mostly dioecious,
rarely monoecious, growing up to 1–6 m in height (Miller 1970 ; Wu et al. 2003 ).
The stems are green, hollow, cylindrical and longitudinally ridged. The extent of
branching is variable; secondary branches vary from opposite to alternate. Leaf
arrangement varies from decussate at lower branches to alternate at terminal ones.
Petioles are up to 7 cm long, cylindrical with a median groove along the upper side,
and covered with non-glandular and glandular trichomes (Fig.5.2e, f); petiolules
are 0.5–1.5 cm long.
The leaves (Fig.5.1a–e) are palmately 3-9-lobed, showing actinodromous
venation (Jiang et al. 2006 ); the youngest leaves are sometimes unlobed. The lobes
are narrowly oblong-lanceolate, 3–20 cm long, up to 1.8 cm wide, dark green
above, paler beneath, attenuate at base, caudate-acuminate at apex, and serrate
along the margins. The serrations along the margins are prominent, curved and
pointed towards the tips of the leaf blades. Each lobe has a primary midrib and
several secondary veins at either side. Each of the secondary veins run out obliquely
from the midrib and enters into a serration of the margin. The veins are prominently
raised forming ridges on the abaxial side whereas they are impressed on the adaxial
side forming grooves. The lowest pair of lobes is usually much smaller than the
others and pointing backwards (Fig.5.1e). In seedlings, thefirst pair of leaves is
1-foliolate and the second and third pairs are three andfive-foliolate, respectively
(Potter 2009 ).
124 V. Raman et al.