ripped from Sensi Seeds web site:
Scientifically (and legally), all cannabis is Cannabis Sativa L..
In practice, Indica and Sativa are the names used to distinguish each end of the cannabis 'spectrum'. There are a multitude of different growth-patterns, qualities and effects within this spectrum, most of which are a result of cannabis' remarkable ability to adapt to its environment. Genetically, and in terms of interbreeding, all cannabis is in the same family.
INDICA:
# Most Indica varieties come from southern Asia and the Indian subcontinent (Afghanistan, Pakistan, India, Tibet, Nepal, etc.).
# Indicas are compact and stocky, with dense, heavy, fragrant buds. Indica buds tend to grow in clusters, with varying amounts of space (known as 'internode space') between each cluster.
# Indicas are the faster flowering varieties, usually with a flowering time of 6 to 9 weeks.
# Indicas do not tend to gain height rapidly once flowering has begun. An Indica may be expected to gain between 50 and 100% of its vegetative height by the end of its flowering period.
# The effect of Indica is generally classified as a 'stone', meaning that it is more centred on the body. It may enhance physical sensations such as taste, touch and sound. It has a relaxing effect - mentally and physically - and may be soporific in larger doses.
SATIVA:
# Sativas generally originate in the equatorial regions - Thailand, Cambodia, Jamaica, Mexico, etc.
# Given the same conditions, Sativas grow taller than Indicas. Sativa buds tend grow larger than Indica, as they run along the length of a branch instead of clustering around the internodes. However, they will usually weigh less than Indica when dry, due to their lower density. Sativa buds also tend to have a less striking odour, both when growing and when dry.
# Sativas take longer to flower. They will usually need between 9 and 12 weeks to finish blooming. However, they need far less vegetative time BEFORE flowering than Indicas. So the overall time required for Sativas is about the same as for Indicas (and sometimes less in terms of 'light hours')
# Sativas will usually continue to gain height while flowering, often gaining 200%, 300% or more of their vegetative height while flowering. This is because around the equator there is not so much difference in the number of daylight hours between winter and summer. Therefore, Sativas in their native environment will grow and flower at the same time. For this reason indoor growers should not allow a Sativa too much vegetative growth before inducing flowering. When growing from clones, many Sativa varieties may be flowered as soon as the clone has rooted.
# Despite their lower weight and potentially longer flowering time, Sativas are valued by many growers for their 'high' effect. This high may be characterized as cerebral, energetic, creative, giggly or even psychedelic. It is less overpowering than the Indica 'stone', and less likely to send the user to sleep.
