As /u/m_s_m said :

"This is Typha Latifolia, commonly known as Cattail. Cattails are used in Latin America in both cooking and traditional medicin.

Rubbing the stem, causes the potassium and nitrogen to oxygenate within stored mitochondria chambers, leading to rapid expulsion of collagenous spaces between the xylem and the phloem.

The same effect occurs when the plant is subject to high levels of heat. This led to a disaster in Le Paz, Bolivia, 1981. Tens of thousands of Cattail stems were being kept in a massive warehouse when a heatwave caused rapid expansion. Over a hundred workers suffocated when the warehouse was suddenly filled by expanding cattails seeds.

Each year, a day of remembrance is held called Día de la Espadaña where adults dress up in traditional factory clothing and children dress up as cattails. The children are then encouraged to attack the adults and beat them with rubber sticks, the adults then runaway and cover themselves with goose fat and anyone not hit by a child is set on fire and sacraficed to their God Urak Misfakunhai. "