Updated: 35 minutes ago
Important Note: This is a compilation of what I have read and learned from the internet, from articles and from short courses materials. I just compiled it in a way easier to understand for my own reference but you are welcome to read and learn from this. If anyone has something to add or edit, please contact me via email and I will be happy to do the revision.
To make the naming of plants more precise and universal, an international system of naming plants is used by scientists and plant professionals. Known as the “International Code of Botanical Nomenclature,” the code is based on a two-name (binomial) system developed by the famous botanist Linnaeus. (Source: Internet, maybe Wikipedia)
Each plant is given a first name and last name, generally based in Latin, that is unique to each species. This name is recognized for that plant throughout the world, no matter what the native language might be.
The scientific name of a plant is consists of two names:
(1) the genus or generic name, and
(2) the specific epithet or species name.
IMPORTANT: There are rules to follow when writing a scientific name.
(1). The genus name is written first.
(2). The genus name is always underlined or italicized.
(3). The first letter of the genus name is always capitalized.
Example : Hoya - H is always capitalized
(1). The specific epithet is written second.
(2). The specific epithet is always underlined or italicized.
(3). The first letter of the specific epithet name is never capitalized.
Example : lacunosa or lacunosa –
The correct way to write Hoya lacunosa therefore is Hoya lacunosa or Hoya lacunosa - you do not write it as lacunosa only. You have to write the word Hoya, with capital H.
Note (MY OPINION): If you are writing Hoya label/names in a facebook, instagram or other plaftfrom posts, or even in your own plant tags, it might be difficult to follow underlining and italizing the words, so as long as you know the rules, I believe its okay, you do not have to follow the rules 100%, there is no hoya police to take you and put you in jail for not following the rules. (But thats just me, so you can blame me if you get told by anyone hahaha).
WHAT ABOUT MUTATIONS ?
The evolution of plant life is based on mutations, which are constantly occurring. Very often a particular individual of a species will mutate to a different color, size, or growth habit. These characteristics are passed on to its progeny (offspring). When this happens, a population of plants exists with the same scientific name, but a sub-group exhibits different characteristics. If the mutated group is significantly different from the parents and is stable (the traits are passed on from generation to generation), then this new group of plants is often assigned a variety name.
Subspecies is one of many ranks below that of species, such as variety, subvariety, form, and subform. To identify the rank, the subspecific name must be preceded by "subspecies" which is abbreviated as ssp.
Example: Hoya australis – Australia, Fiji, Indonesia (Irian Jaya), Papua New Guinea, Solomon Islands, Tonga •
Subspecies of Hoya australis:
Hoya australis ssp. australis – Australia (Queensland, New South Wales), Samoa, Vanuatu • Hoya australis ssp. oramicola – Australia (Northern Territory) •
Hoya australis ssp. rupicola – Australia (Western Australia, Northern Territory)
Hoya australis ssp. sanae Australia (Queensland)
Hoya australis ssp. tenuipes – Australia (Queensland), Fiji, Indonesia (Irian Jaya), Papua New Guinea, Solomon Islands, Tonga
Variety names are given when the mutation occurs in nature.
(1) The abbreviation var. is used to signify that the mutation is a variety.
(2) var. is placed after the specific epithet and is not underlined or italicized.
Mutations can also occur because of human interventions such as breeding, applying mutagens, propagation, or by cultural practices. In these cases, the new group of mutated plants is called a cultivar.
"Cultivar" is an abbreviated form of cultivated variety. The mutated plants are assigned a cultivar name. · The cultivar name is written after cv. or within the single quotes.
Capitalize the first letter of but never underline or italicize the cultivar name. If it is a result of breeding two species, then you need to write the names of the parents and then followed by the cultivar name.
Example: Hoya obscura x Hoya lacunosa ssp. pallidiflora cv. Sunrise or Hoya obscura x Hoya lacunosa ssp. pallidiflora ‘Sunrise’
In short - if a you see a Hoya name with var. after the species name, then it means the mutation occurs in nature, in the wild. If you see a Hoya label with cv. after the species name, then it means it is cultivated, man-made or created by man.
Species affinis (commonly abbreviated to: sp. aff., aff., or affin.)
In open nomenclature it indicates that available material or evidence suggests that the proposed species is related to, has an affinity to, but is not identical to, the species with the binomial name that follows.
 The Latin word affinis can be translated as closely related to, or akin to or compares favourably to:
Ex: Hoya sp. aff. carnosa – this means it is a hoya that is similar to carnosa but it is not carnosa.
HOYA NOT IDENTIFIED OR MATCHED TO A PREVIOUS PUBLICATION OR NOT PUBLISHED
When a hoya is not identified or matched to a previous publication or not published, it is given a temporary name:
Ex: Hoya sp. IML 9999 means it is a hoya but the species is not yet published or identified, and it is from David Liddle’s (IML) collection and he put an ID# of 9999 for that particular hoya.
When you see Hoya sp. written in the label, you can translate it as yes, it is a Hoya but the species is unknown.
When in doubt of a Hoya name, see below photo.