This is what a sesame plant looks like.

Sesame seeds are actually the seeds of an annual herb, so they do not grow from trees. But since mature sesame plant can grow to 1-1.5m(3-5ft) tall, it looks like a bunch of small trees.

Here are the steps my father told me how my grandma used to hull the sesame seeds by hand when he was little.

1. When the sesame plants reach maturity (usually takes 4 months), the flowers will develop into dozens od shells containing seeds in it.
   
2. My grandma would reap the sesame plants and tie them into bundles.
   
3. After bringing gathered bundles back home, she put stacks of sesame plants against the wall in order to let it dry in the sun.
   
4. Once it get dried, those little pots will get cracked naturally. My grandma used to put a piece of cloth underneath the plants, and collect the seeds by hitting and shaking the plant by holding it upside down.
   
5. Then the seeds all fall out. My grandma would keep the the stalks of the sesame plant because those are good materials to build fire.

Click to have a closer look at sesame plants