Our Tulsi Mala (prayer beads) is made from the Tulsi plant, also known as Holy Basil. Tulsi malas contain 108 beads held together by a sacred thread, along with a "guru" bead which is attached to the tassel. The threads are knotted between each bead.
From The Magic Ten and Beyond book by Jivamukti founder Sharon Gannon:
"Traditionally yogis used a mala as a meditation tool, to keep track of counting while chanting a mantra. Holding each bead and silently reciting a mantra is called japa meditation. Japa means "mantra repetition"; you continue to recite the same mantra over and over, using the mala to maintain your focus. When you get to the end of the mala, there is a "guru" bead. You should never pass over the guru bead; instead flip the mala around and start over from the other end.