Robbins

Robbins (2010) described marker pens as pens which have their own ink source and usually has a tip made of absorbent and pressed fiber and was first created by Sidney Rosenthal in 1952. This marker pen had been one of the commonly used writing instruments for about fifty years.
Alugbati, known in the U.S. as Malabar spinach, is commonly grown for its soft, spinach-like leaves and shoots. Alugbati is of African and East Asian origin. The juice of the fruits was reportedly used in ancient China as ink for official seals. Today, the fruits of the red-stemmed alugbati variety can be used to make ink. As of May 2010, the government of the Philippines is researching commercial production of ink extracted from the alugbati fruits (Darci Pauser).