Gemüse & Obst (Grammar Question)
As I was doing some of the early Duolingo lessons for German I became confused with the pronouns for these two particular words: Gemüse (vegetable) and Obst (fruit). Do these words have plural forms? If so, when would I use them versus the singular forms?
Obst and Gemüse are collective nouns and don't really require a plural, at least for the most common uses. (Ge- is a German prefix that typically introduces a collective noun, though the example of Obst shows that not all German collectives have it.)
When referring to an individual fruit you would say ein Stück Obst or eine Frucht. I don't think I have ever heard anyone refer to an individual vegetable in German other than by specifying the kind of vegetable, but I guess you could say ein Stück Gemüse if you absolutely want to.
Ein Gemüse is short for eine Gemüsesorte, i.e. a kind of vegetable. When used in this way, there is a plural - zwei Gemüse. It is rarely used, as people prefer the unambiguous Gemüsesorten.
As you can't really say ein Obst (don't ask me why!), there is no need for a plural of Obst. Nevertheless, most German speakers seem to agree that if Obst had a plural, then it would be Öbste. If this plural existed, it would no doubt refer to kinds of fruit. By googling for "andere Öbste" you can easily find 9 real usage examples for this innovation including two instances of "Äpfel und andere Öbste". But the comparison to 44,000 hits for "andere Gemüse" shows that this is by no means standard usage.
What this shows is that some overgeneralisations made by language learners are indistinguishable from creative language use by native speakers. Be bold!