Marijuana (Cannabis sativa)

Marijuana
Cannabis sativa
(Order: Urticales; Family: Cannabaceae)

Female Cannabis sativa (photo: Anna Balthazor)

Diagnosis:

Marijuana is a dioecious (male and female flowers are on separate plants) annual. Males are typically taller than female plants and can vary in height, but are usually between 1-3 m. The stalk is hollow and the leaves are palmate with serrated edges, typically numbering 5-7 leaves. Males fertilize female plants by wind pollination.

(image from: http://www.diy-medijuana.org/plant/cannabis-sativa-botany) A - flowering male B - seed-bearing female plant 1 - male flower cluster, enlarged detail 2 - pollen sac (anthers) 3 - trichome covered leaf, enlarged detail 4 - trichome 5 - female flower with cover petal (calyx) 6 - female flower, calyx removed 7 - female fruit cluster, calyx removed, longitudinal section 8 - fruit (seed) with (calyx) 9 - seed, front view 10 - seed, side view 11 - seed, cross-section 12 - seed, longitudinal section 13 - seed without hull 14 - stigmas

Flowering Period:

Flowering begins when day length starts to decrease and dark hours exceed eleven hours per day.

Distribution:

(Image from: http://plants.usda.gov/java/profile?symbol=CASA3)

Habitat:

Plants prefer neutral to alkaline clay and loam soils but will grow almost anywhere. It can be seen in ditches, fields, riparian areas, greenhouses, and basements with adequate artificial lighting.

Visitors:

Male plants are visited by ants, bees and various flies even though Marijuana is anemophilous (wind pollinated).

Human Uses:

Marijuana has been used by humans for the last 5,000 years for medicine, textiles, paper, rope, seed oil, food, religious ceremonies and recreation. More recently, Marijuana is cultivated for biodegradable plastics, construction materials, cosmetics and bio-fuel. The plant contains a psychoactive chemical, THC (tetrahydrocannabinol), which provides users with euphoric feelings; at higher doses it can induce feelings of paranoia and anxiety. The Cannabis sativa seeds contain high levels of protein, fatty acids, and vitamins. Strains of Marijuana are grown with reduced levels of THC (called hemp) and harvested for their fibers which have excellent tensile strength. Hemp is considered to be an environmentally friendly crop because it requires little fertilizer, few pesticides and no herbicides.

Conservation Status:

Not Applicable

Native Status:

Native to Asia

Links:

How Stuff Works: http://science.howstuffworks.com/marijuana1.htm

Hemp Farming: http://www.hempfarm.org/Papers/Hemp_Facts.html

Videos:

The Many Uses of Hemp

Medical Drug Research Using Cannabis Sativa

References:

Elpel, Thomas J. 2008. Botany in a Day: The Patterns Method of Plant Identification. 5^th Edition. HOPS Press, LLC. Pony, Montana.

Rana, Anita  and Namrta Choudhary. 2010. Floral Biology and Pollination Biology of Cannabis sativa L. The International Journal of Plant Reproductive Biology 2(2) pp. 191-195.

Stewart, Amy. 2009. Wicked Plants: The Weed That Killed Lincoln’s Mother and Other Botanical Atrocities. Algonquin Books of Chapel Hill. Chapel Hill, North Carolina.

UNODC (United Nations Office on Drugs and Crime). 2009. Recommended Methods for the Identification and Analysis of Cannabis and Cannabis Products. United Nations. New York.

http://www.diy-medijuana.org/plant/cannabis-sativa-botany

http://plants.usda.gov/java/profile?symbol=CASA3

Submitted by Anna Balthazor, July 2012