Zero-inflection plurals do not include cucumber.
This package of Japanese Kyuri from Malaysia says:
Rich in nutrients, Cucumber are excellent in salads, sandwiches, stir-fry and sushi.
Here, the fact that the singular is being treated like a plural makes it sound as if cucumbers are exotic animals like bison or buffalo.
Recently, though I don’t have a photo, I saw a sign in front of some model planes (in the Tin Tin shop strangely located on Pagoda St in Chinatown) that was advertising “aircrafts for sale”. Ack. No.
For a variety of historical reasons, English has many kinds of nouns that are annoyingly difficult to pluralize, and Wikipedia helpfully lists them.
Interestingly, the cucumber package shows ‘salads’, ‘sandwiches’, ‘stir-fry’, and ‘sushi’ all in the correct form, even though ‘salad’ requires an ‘s’, ‘sandwich’ requires ‘es’, and ‘stir-fry’ and ‘sushi’ are uncountable.
Why, then, was it so hard to give ‘cucumber’ its plural ‘s’?
And why is it capitalized?!