Traditional Dreadlocks styles are now being referred to as Freeform or organic.  The most well known example of freeform dreadlocks is the Reggae king himself, Bob Marley.

Freeform dreadlocks are traditionally associated with Rastafarians. This dreadlocking method tends to produce dreadlocks faster than any other method and is a "wash and go" style.

Besides shampooing, the hair is not manipulated to a great degree. Over time, your hair will matte and dreadlock.

Some use a "pluck
ing" method to encourage the hairs to separate and form individual dreads.

Another method for shorter hair is after shampooing, towel dry the hair in a circular motion to encourage the hair to develop its own clusters. Overtime the clusters will matte and as they grow will form individual dreadlocks.

Freeform dreadlocks are often called "Organic" because they're considered more holistic and truer representatives of the dreadlock tradition.  These types of dreadlocks tend to get a bad rap in and outside the dreadlock'd community due to the fact that they generally lead to uneven or flattened dreads.  As a result, another name for freeform is the "neglect method."

Now don't get me wrong, I've seen organic dreadlocks that are uniform and even.  Although freeforming is a minimalist method, there are those who do engage in some sort of twisting either to help encourage a new dread to take place or to strengthen areas that may have weakened.

Typically what happens with freeform dreadlocks is crawling.  Crawling is a process by which individual dreadlocks begin sharing a root bed.  Over time, two or more dreadlocks connect at the root leading to spider dreads/two-headed dragons/treeing/y-locks (different names for the same thing).  Spider dreads are those which if you follow them down start as one lock but begin to branch off into two or more individual ones.

Depending on how they're cared for, the spider dreadlocks can either remain as is or over time, the tree'd ends may begin to adhere to one another through Natural processes or when the person marries/combines them.  

When the spider dreadlocks are combined, a second process of matting begins and one, large dreadlock takes shape.