The relevant international bodies are the UNODC and the related Commission on Narcotic Drugs https://www.unodc.org/unodc/en/commissions/CND/index.html, and the UN International Narcotics Control Board, which along with the WHO are treaty-mandated bodies in the international control of drugs.
The INCB in 'Contribution of the International Narcotics Control Board
to the high-level review of the implementation by Member States of the Political Declaration and Plan of Action on International Cooperation towards an Integrated and Balanced Strategy to Counter the World Drug Problem' state
Under the 1961 [Narcotics] Convention and that Convention as amended
by the 1972 Protocol, plants that are the sources of narcotic drugs,
such as cannabis plant, opium poppy and coca bush, are subject to
specific control measures. In contrast, although some active stimulant
or hallucinogenic ingredients contained in certain plants are
controlled under the 1971 [Psychotropic] Convention, no plants are
currently controlled under that Convention or under the 1988
Convention. Preparations (e.g. decoctions for oral use) made from
plants containing those active ingredients are also not under
Examples of such plants or plant material include khat (Catha edulis),
whose active ingredients cathinone and cathine are listed in Schedules
I and III of the 1971 Convention ... magic mushrooms (Psilocybe), which contain psilocybine and psilocine;
- The Board notes that, in view of the health risks associated with the abuse of such plant material, some Governments have placed certain
types of plant material and preparations under national control. The
Board recommends that Governments that have not yet done so and have
experienced problems with regard to persons engaging in the
recreational use of or trafficking in such plant material, to .. consider controlling such plant
material at the national level where necessary
Therefore it follows that there is no distinction between khat and magic mushrooms in terms of the UN Convention, and neither are Scheduled drugs in terms of international law.
This status was confirmed in a letter from the INCB of 2001 to the Dutch Ministry of Health, which was confirmed by the "INCB Secretariat with the Scientific Section and the Legal Advisory Section of the United Nations International Drug Control Programme", with regards to a question about the legality of magic mushrooms.
It follows that the only plants controlled under international law as narcotics are opium, cannabis and coca. Other plants (or fungi!) are not Scheduled psychotropics.
Thus for example the source in my question claiming 'In 1971, the United Nations Convention on Psychotropic Substances which includes psilocybin mushrooms on the list of illicit products was signed'. is wrong; the chemical psilocybin is listed, but plants/fungi that contain it are not covered.
The US Controlled Substances Act uses two different wordings. E.g., in Schedule I:
- 'any of the following opiates/opium derivatives including their isomers, esters, ethers, salts, and salts of isomers, esters, and ethers, whenever the existence of such isomers, esters, ethers, and salts '
- 'any material, compound, mixture, or preparation, which contains any quantity of the following ... substances'
The 'any material' definition includes plants containing controlled substances, with lists that include, inter alia, psilocybin, psilocin, cathine, cathinone. In US v. Mire (2013), the US Court of Appeals 7th Circuit, affirmed that this makes khat a federally controlled substance.
It follows therefore that:
- The cited international treaties do not restrict any plants as controlled drugs, other than coca, the opium poppy, and cannabis.
- Countries may choose to implement these treaties in more restrictive ways, and in the US at least many hallucinogenic plants are prohibited under US law.
- There is no difference between khat and magic mushrooms at international law, but magic mushrooms may be more prevalent in Western countries and hence more likely to be restricted at domestic law