Chapter 1 - Sinsemilla Life Cycle of Cannabis
Cannabis is a tall, erect,
annual herb.
Provided with an open sunny environment,
light well-drained composted soil, and ample
irrigation, Cannabis can grow to a height of
6 meters (about 20 feet) in a 4-6 month
growing season. Exposed river banks, mead-
ows, and agricultural lands are ideal habi-
tats for Cannabis since all offer good sun-
light. In this example an imported seed
from Thailand is grown without pruning
and becomes a large female plant. A cross
with a cutting from a male plant of Mexi-
can origin results in hybrid seed which is
stored for later planting. This example is
representative of the outdoor growth of
Cannabis in temperate climates.
Seeds are planted in the
spring and
usually germinate in 3 to 7 days. The seed-
ling emerges from the ground by the
straightening of the hypocotyl (embryonic
stem). The cotyledons (seed leaves) are
slightly unequal in size, narrowed to the
base and rounded or blunt to the tip.
The hypocotyl ranges from
1 to 10
centimeters (1A to 3 inches) in length. About
10 centimeters or less above the cotyledons,
the first true leaves arise, a pair of oppo-
sitely oriented single leaflets each with a
distinct petiole (leaf stem) rotated one-
quarter turn from the cotyledons. Subse-
quent pairs of leaves arise in opposite
formation and a variously shaped leaf se-
quence develops with the second pair of
leaves having 3 leaflets, the third 5 and so
on up to 11 leaflets. Occasionally the first
pair of leaves will have 3 leaflets each rather
than 1 and the second pair, 5 leaflets each.
If a plant is not crowded,
limbs will
grow from small buds (located at the inter-
section of petioles) along the main stem.
Each sinsemilla (seedless drug Cannabis)
plant is provided with plenty of room to
grow long axial limbs and extensive fine
roots to increase floral production. Under
favorable conditions Cannabis grows up to
7 centimeters (21A inches) a day in height
during the long days of summer.
Cannabis shows a dual response
to
daylength; during the first two to three
months of growth it responds to increasing
daylength with more vigorous growth, but
in the same season the plant requires shorter
days to flower and complete its life cycle.
LIFE CYCLE OF CANNABIS I Juvenile Stage
Cannabis flowers when exposed
to a
critical daylength which varies with the
strain. Critical daylength applies only to
plants which fail to flower under continu-
ous illumination, since those which flower
under continuous illumination have no criti-
cal daylength. Most strains have an absolute
requirement of inductive photoperiods
(short days or long nights) to induce fertile
flowering and less than this will result in
the formation of undifferentiated primor-
dia (unformed flowers) only.
The time taken to form primordia
varies with the length of the inductive pho- -
toperiod. Given 10 hours per day of light a
strain may only take 10 days to flower,
whereas if given 16 hours per day it may
take up to 90 days. Inductive photoperiods
of less than 8 hours per day do not seem to
accelerate primordia formation. Dark
(night) cycles must be uninterrupted to in-
duce flowering (see appendix).
Cannabis is a dioecious
plant, which
means that the male and female flowers
develop on separate plants, although mono-
ecious examples with both sexes on one
plant are found. The development of
branches containing flowering organs varies
greatly between males and females: the
male flowers hang in long, loose, multi-
branched, clustered limbs up to 30 centi-
meters (12 inches) long, while the female
flowers are tightly crowded between small
leaves.
Note: Female
Cannabis flowers and
plants will be referred to as pistillate and
male flowers and plants will be referred to
as staminate in the remainder of this text.
This convention is more accurate and makes
examples of complex aberrant sexuality
easier to understand.
The first sign of flowering
in Cannabis
is the appearance of undifferentiated flower
primordia along the main stem at the nodes
(intersections) of the petiole, behind the
stipule (leaf spur). In the prefloral phase,
the sexes of Cannabis are indistinguishable
except for general trends in shape.
When the primordia first
appear they
are undifferentiated sexually, but soon the
males can be identified by their curved
claw shape, soon followed by the differen-
tiation of round pointed flower buds having
five radial segments. The females are recog-
nized by the enlargement of a symmetrical
tubular calyx (floral sheath). They are easier
to recognize at a young age than male pri-
mordia. The first female calyxes tend to
lack paired pistils (pollen-catching appen-
dages) though initial male flowers often
mature and shed viable pollen. In some in-
dividuals, especially hybrids, small non-
flowering limbs will form at the nodes and
are often confused with male primordia.
Cultivators wait until actual flowers form
to positively determine the sex of Cannabis
The female plants tend to
be shorter
and have more branches than the male.
Female plants are leafy to the top with
many leaves surrounding the flowers, while
male plants have fewer leaves near the top
with few if any leaves along the extended
flowering limbs.
*The term pistil has developed a special meaning
with respect to Cannabis which differs slightly
from the precise botanical definition. This has
come about mainly from the large number of culti-
vators who have casual knowledge of plant anatomy
but an intense interest in the reproduction of Can-
nabis. The precise definition of pistil refers to the
combination of ovary, style and stigma. In the
more informal usage, pistil refers to the fused style
and stigma. The informal sense is used throughout
the book since it has become common practice
among Cannabis cultivators.
The female flowers appear
as two long
white, yellow, or pink pistils protruding
from the fold of a very thin membranous
calyx. The calyx is covered with resin-
exuding glandular trichomes (hairs). Pistil-
late flowers are borne in pairs at the nodes
one on each side of the petiole behind the
stipule of bracts (reduced leaves) which
conceal the flowers. The calyx measures 2
to 6 millimeters in length and is closely
applied to, and completely contains, the
ovary.
In male flowers, five petals
(approxi-
mately 5 millimeters, or 3/16 inch, long)
make up the calyx and may be yellow,
white, or green in color. They hang down,
and five stamens (approximately 5 milli-
meters long) emerge, consisting of slender
anthers (pollen sacs), splitting upwards from
the tip and suspended on thin filaments.
The exterior surface of the staminate calyx
is covered with non-glandular trichomes.
The pollen grains are nearly spherical
slightly yellow, and 25 to 30 microns (p)
in diameter. The surface is smooth and ex-
hibits 2 to 4 germ pores.
Before the start of flowering,
the
phyllotaxy (leaf arrangement) reverses and
the number of leaflets per leaf decreases
until a small single leaflet appears below
each pair of calyxes. The phyllotaxy also
changes from decussate (opposite) to alter-
nate (staggered) and usually remains alter-
nate throughout the floral stages regardless
of sexual type.
The differences in flowering
patterns
of male and female plants are expressed in
many ways. Soon after dehiscence (pollen
shedding) the staminate plant dies, while
the pistillate plant may mature up to five
months after viable flowers are formed if
little or no fertilization occurs. Compared
with pistillate plants, staminate plants show
a more rapid increase in height and a more
rapid decrease in leaf size to the bracts
which accompany the flowers. Staminate
plants tend to flower up to one month ear-
lier than pistillate plants; however, pistillate
plants often differentiate primordia one to
two weeks before staminate plants.
Many factors contribute
to determin-
ing the sexuality of a flowering Cannabis
plant. Under average conditions with a nor-
mal inductive photoperiod, Cannabis will
bloom and produce approximately equal
numbers of pure staminate and pure pistil-
late plants with a few hermaphrodites (both
sexes on the same plant). Under conditions
of extreme stress, such as nutrient excess or
deficiency, mutilation, and altered light
cycles, populations have been shown to de-
part greatly from the expected one-to-one
staminate to pistillate ratio.
Just prior to dehiscence,
the pollen
nucleus divides to produce a small repro-
ductive cell accompanied by a large vegeta-
tive cell, both of which are contained
within the mature pollen grain. Germina-
tion occurs 15 to 20 minutes after contact
with a pistil. As the pollen tube grows the
vegetative cell remains in the pollen grain
while the generative cell enters the pollen
tube and migrates toward the ovule. The
generative cell divides into two gametes
(sex cells) as it travels the length of the
pollen tube.
Pollination of the pistillate
flower re-
sults in the loss of the paired pistils and a
swelling of the tubular calyx where the
ovule is enlarging. The staminate plants die
after shedding pollen. After approximately
14 to 35 days the seed is matured and drops
from the plant, leaving the dry calyx at-
tached to the stem. This completes the nor-
mally 4 to 6 month life cycle, which may
take as little as 2 months or as long as 10
months. Fresh seeds approach 100% viabil-
ity, but this decreases with age.
The hard mature seed is
partially sur-
rounded by the calyx and is variously pat-
terned in grey, brown, or black. Elongated
and slightly compressed, it measures 2 to 6
millimeters (1/16 to 3/16 inch) in length
and 2 to 4 millimeters (1/16 to 1/8 inch) in
maximum diameter
Careful closed pollinations
of a few
selected limbs yield hundreds of seeds of
known parentage, which are removed after
they are mature and beginning to fall from
the calyxes. The remaining floral clusters
are sinsemilla or seedless and continue to
mature on the plant. As the unfertilized
calyxes swell, the glandular trichomes on
the surface grow and secrete aromatic THC-
laden resins. The mature, pungent, sticky
floral clusters are harvested, dried, and
sampled. The preceding simplified life cycle
of sinsemilla Cannabis exemplifies the pro-
duction of valuable seeds without compro-
mising the production of seedless floral
clusters.