The term "parent plant" in the pharmaceutical definition refers to a defined plant species from which a pharmaceutical drug is produced using various processes and preparations.
The parent plant is named according to its biological nomenclature (botanical name, including author abbreviation, e.g. L. for Linné).
The parent plant designates the origin of a herbal drug. The drug is usually only obtained from a specific part of the plant (flowers, roots, rhizomes, above-ground herb, etc.). It is prepared using various standardized processes.
For example, "Panax ginseng C.A. Meyer", the ginseng plant named after C.A. Meyer, is the parent plant of Ginseng Radix, the official ginseng root monographed by Commission E, also known as Panax root. For this drug, only the dried roots of the ginseng plant obtained by steam distillation are used and not the whole plant (parent plant).
Lavendula angustifoliae Mill., the lavender plant, is the parent plant of Lavendulae flos also known as Flores Lavendulae, the official drug "lavender flowers" defined by various monographs. This drug is obtained exclusively from the fresh, unblossomed flowers of the lavender plant.
In the case of Quercus cortex, the official oak bark monographed by various commissions, there are several parent plants (Quercus rubor L. (L. stands for the author Linné), Quercus petraeae, Quercus pubescens) whose cut and dried bark, as well as their fresh young twigs, are processed together to produce the drug "Quercus cortex".