Indica and sativa are the two main types of cannabis. Here's how to tell them apart.

Cannabis is one of the oldest crops known to mankind, with records of its cultivation dating back thousands of years.

Today, it is widely accepted that marijuana has two different species: Cannabis indica and Cannabis sativa. Cross-breeding of the two types has led to a wide variety of hybrid strains with unique characteristics.

The differences between indica and sativa remain a subject of much debate, especially among scientists who study the plant. However, most agree that indica and sativa plants are distinct in a number of ways.

Appearance:
The most accepted way of distinguishing indica versus sativa is by appearance, or what scientists refer to as morphology.

Sativa plants are tall, loosely branched and have long, narrow leaves. They are usually grown outdoors and can reach heights of up to 20 feet.

Indica plants are short, densely branched and have wider leaves. They are better suited for growing indoors.

Effects: Besides appearance, indica and sativa plants are commonly believed to have different effects on their user.

Sativa effects:
- uplifting and energetic
- cerebral, spacey or hallucinogenic
- best suited for day use

Indica Effects:
- relaxing and calming
- body buzz or 'couch lock'
- best suited for night use

However, no scientific study has confirmed these differences, and there is some doubt about their accuracy. In fact, history suggests a much simpler difference between indica and sativa.

Source: http://www.leafscience.com/2014/06/19/indica-vs-sativa-understanding-differences/