In Croatian, collective nouns are often used to talk about groups of inanimate objects in nature. Common examples include drveće (trees), lišće (leaves), cvijeće (flowers), grmlje (bushes), and kamenje (stones). They are formed by adding -je or -e to the root of the word (often with a consonant change, like drvo to drveće).
Neuter Singular Agreement
The most important rule for these collective nouns is that, although they translate to plurals in English, they are grammatically neuter singular in Croatian. Verbs, adjectives, and pronouns describing them must also be neuter singular.
Declining Collective Nouns
Because they function as singular neuter nouns, they decline exactly like standard neuter nouns ending in -e (like more). For example, after prepositions that require the genitive case, the -e changes to -a (e.g., drveća, kamenja).
A Note on "Grablje" (Rake)
Be careful not to confuse neuter collective nouns with the word for a rake, grablje. Although it also ends in -je, grablje is a feminine plural noun—a word that only exists in the plural, much like "scissors" in English.
When used in the instrumental case, grablje takes the standard feminine plural ending -ama, and its adjectives must also be in the plural.