Maybe logic: I searched for plant, manufacture and production. Tabernanthe iboga isn't mentioned.
One could argue that a plant is a material.
If a plant is a material, this may applicable to seeds.
§ 841. Prohibited acts A.
(a) Unlawful acts
Except as authorized by this subchapter, it shall be unlawful for any person knowingly or intentionally
(1) to manufacture, distribute, or dispense, or possess with intent to manufacture, distribute, or dispense, a controlled substance; or
[..]
(15) The term ''manufacture'' means the production, preparation, propagation, compounding, or processing of a drug or other substance, either directly or indirectly or by extraction from substances of natural origin, or independently by means of chemical synthesis or by a combination of extraction and chemical synthesis, and includes any packaging or repackaging of such substance or labeling or relabeling of its container;
[..]
(22) The term ''production'' includes the manufacture, planting, cultivation, growing, or harvesting of a controlled substance.
[..]
(g) Plants
(1) All species of plants from which controlled substances in schedules I and II may be derived which have been planted or cultivated in violation of this subchapter, or of which the owners or cultivators are unknown, or which are wild growths, may be seized and summarily forfeited to the United States.
One could argue that a plant is a material.
Unless specifically excepted or unless listed in another schedule, any material, compound, mixture, or preparation, which contains any quantity of the following hallucinogenic substances, or which contains any of their salts, isomers, and salts of isomers whenever the existence of such salts, isomers, and salts of isomers is possible within the specific chemical designation:
(8) Ibogaine.
If a plant is a material, this may applicable to seeds.
The following shall be subject to forfeiture to the United States and no property right shall exist in them:
(2) All raw materials, products, and equipment of any kind which are used, or intended for use, in manufacturing, compounding, processing, delivering, importing, or exporting any controlled substance in violation of this subchapter.