Serapion the Younger was the author of a medicinal-botany book entitled The Book of Simple Medicaments. The book is dated 12th or 13th century. He is called "the Younger" to distinguish him from Serapion the Elder, aka Yahya ibn Sarafyun, an earlier medical writer with whom he was often confused. Serapion the Younger's Simple Medicaments was likely written in Arabic, but no Arabic copy survives, and there is no record of a knowledge of the book among medieval Arabic authors. The book was translated to Latin in the late 13th century and was widely circulated in late medieval Latin medical circles. Portions of the Latin text make a good match with portions of a surviving Arabic text Kitab al-adwiya al-mufrada attributed to Ibn Wafid (died 1074 or 1067). The entire Latin text is very heavily reliant on medieval Arabic medicinal literature; and it is essentially just a compilation of such literature. It is exceedingly clear that the book was not originally written in a Latin language.
Nothing about Serapion the Younger's biography is on record anywhere. In his only book, there is a quote from something by a certain medical writer who died around 1070 (Ibn Wafid). That puts a lower bound on when Serapion the Younger wrote. It is therefore supposed he wrote in the 12th century. It remains possible he wrote in the 13th century because there is no record of the full book anywhere until the late 13th century. On the basis of his name he might have been a Christian because "Serapion" and its Arabic equivalents "Sarafyun" and "Sarabi" is a Greek name. But since the identity of this Serapion is completely unknown, his name Serapion can be a pseudepigraph, whereby he was using the authority of the name of the earlier Serapion to give more credence to his own work. He calls himself the very same name as Serapion the Elder called himself. The distinction between "the Younger" and "the Elder" was introduced later by others after it was realized that they cannot be the same person. Pseudepigraphy was common in the medieval era.
In the title Simple Medicaments, "simple" means non-compound: a practical medicine most often consisted of a mix of two or more "simples". The work was written for physicians and apothecaries. In the book's early part, Serapion the Younger classifies substances according to their medicinal properties, and discourses on their actions. The remainder and largest part of the book is a compendium of information on individual medicaments quoted from Dioscorides, Galen, and numerous named medieval Arabic writers on medicaments, with relatively brief supporting remarks by himself.