One of the richest textual traditions in the History of Arabic sciences is that of the Books of Simples, Kutub al-Adwyia al-Mufrada. Lying at the intersection of the disciplines of Botany and Medicine, this tradition refers to the study of the medicinal uses of plants. The two major texts that have provided the basis for this tradition are Dioscorides’ On Simple Drugs and Galen’s On the Powers of Simple drugs, with their translation to Arabic and Syriac began a long tradition of independent works by Arab botanists and physicians that lasted for centuries. In my paper, I examine one of the earliest works written in this tradition, Aḥmad ibn Abī al-Ashʿath’ (d.970) Kitāb al-Adwyia al-Mufrada, The Book of Simple drugs. Ibn Abī al-Ashʿath, a court physician working in the Ḥamdānid court in Mosul, was revered as a medical authority and widely cited by later authors. In this work, he combines Galen’s focus on drug theory with Dioscorides’ detailed botanical description and analysis of the medicinal uses of plants. He draws on his own experience, as well as range of other works to address the gaps that he saw in the works of those authors. I will discuss two main aspects of this work: First, the innovative ways whereby Ibn Abī al-Ashʿath’ reconciled between previous authorities in his work. Second, how he was able to reconcile between the textual authority of the Greek tradition and his own experiential knowledge. I argue that this two-folded reconciliation process would reveal the innovative contributions of Arabic scholars of the formative period to the development of the disciplines of Botany and Medicine. More specifically, it will reveal how they critically analyzed and challenged the textual authority of the Greek Scientific tradition, how they assimilated and “indigenized” this textual knowledge to render it intelligible reflecting their own proximate environment; and finally, how they incorporated knowledge about their own local environments to produce new knowledge about the natural world. This examination will identify the characteristics of the formative stage of Arabic Botany, thus addressing the scholarly gap in the history of this discipline. More broadly, it will give insights into the mechanics of the appropriation and the assimilation of the Greek and Late Antique Sciences by Arab Scholars during the Formative period of Islamic History.