Botanical Latin

Botanical Latin is a technical language based on Neo-Latin, used for descriptions of botanical taxa. From 1935 thru 2011, the International Code of Botanical Nomenclature mandated Botanical Latin to be used for the descriptions of new taxa (other than algae or fossils). It is still the only language other than English accepted for descriptions. The names of organisms governed by the Code also have forms based on Latin.
Botanical Latin is primarily a written language. It includes taxon names derived from any language or even arbitrarily derived, and consequently there is no single consistent pronunciation system. When speakers of different languages use Botanical Latin in speech, they use pronunciations influenced by their own languages, or, notably in French, there may be variant spellings based on the Latin. There are at least two pronunciation systems used for Latin by English speakers. Neither system, however, works across the full spectrum of botanical names, because many non-Latin words, such as people's names, have been used.
Alphonse Pyramus de Candolle described the language in 1880:
De Candolle estimated that to learn Botanical Latin would take three months' work for an English speaker not already familiar with any language of Latin origin, and one month for an Italian.
William T. Stearn wrote:
Latin names of organisms are generally used in English without alteration, but some informal derivatives are used as common names. For example, the -idae ending of subclass names is changed to -ids (e.g., Rosidae produces rosids); the subfamily ending -oideae is changed to -oids (e.g., Papilionoideae produces papilionoids). The -ids common names have, however also been adopted as rankless clade names, sometimes containing further -ids clade names, so that, for example, in the APG IV classification, rosids contain both fabids and malvids.
More extensive modifications to the spelling and pronunciation are routinely used in some other languages. French organism names are usually gallicized. For example: Chlorophyceae becomes Chlorophycées; Portulacineae becomes Portulacinées.
The Pre-Classical Latin alphabet consisted of 21 letters, to which y and z were added in the Classical epoch, w was later added, and the vowel/consonant pairs i and j, u and v, were later separated. This 26-letter alphabet is used for taxon names in Botanical Latin. Diacritics are not used in names, and a dieresis is considered an optional mark that does not affect spelling.
Some English speakers, and some speakers of other languages, use the reconstructed pronunciation guide for Classical Latin when speaking Botanical Latin words. Latin names pronounced by gardeners and English botanists usually follow a system close to English. It differs greatly from classical pronunciation, and also from Ecclesiastical Latin pronunciation (which is based on Italian, and has, for example, c before i or e pronounced as ch).
Every vowel is pronounced, except diphthongs, which are treated as single long vowels.
The rules also create difficulties with the -ii and -iae endings derived from personal names, because the stress falls in a place that is not usual for those names.
The following table is simplified from Stearn 1992. The pronunciation transcriptions for medical terminology in major medical dictionaries, such as Dorland’s Illustrated Medical Dictionary and Stedman's Medical Dictionary, match these values.