Botanical Latin
 Lesson 11 - Fifth Declension Nouns


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(updated 19 September 2025)

In this lesson you will learn the fifth declension. The diagnostic genitive singular ending for fifth declension nouns is “-eī” or “-ēī”.

To form the fifth declension, drop the -eī (or -ēī ending from the genitive singular—this gives the stem—and add the fifth declension endings (given in tables 11.1 and 11.2 below). For example, the genitive singular of the Latin word for species is species. Drop the -[UUU] and you have the stem [ZZZ].


Table 11.1 - fifth declension endings for both masculine and feminine nouns
case singular plural
nominative stem + ēs stem + ēs
genitive stem + eī stem + ērum
dative stem + eī stem + ēbus
accusative stem + em stem + ēs
ablative stem + ē stem + ēbus


Table 11.2 - (feminine) example: species, speciei (species; without macrons)
case singular plural
nominative species species
genitive speciei specierum
dative speciei speciebus
accusative speciem species
ablative specie speciebus


Table 11.3 - fifth declension endings for neuter nouns
case singular plural
nominative stem + ēs stem + ēs
genitive stem + ēī stem + ērum
dative stem + ēī stem + ēbus
accusative stem + em stem + ēs
ablative stem + ē stem + ēbus


There are relatively few fifth declensions nouns in botanical Latin, as is also true in classical Latin.

Vocabulary
There are only two fifth-declension nouns used in diagnoses in Species Plantarum: series and superficies. The word species is included here because it occurs in the title of the book.

species (f) - species
 series (f) - series
 superficies (f) - upper surface


Latin Descriptions and Diagnoses -


Exercises - For answers, please click here.
Translate the following into English. Because no macrons are used, you will be told when there is an ablative case.
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Write the following in Latin.
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Write a Latin description for the following. These are more challenging. You have to convey the meaning rather than following the exact wording.
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