Can the word "fruit" be used as an invariant plural as in "the fruit are" and "two fruit"? [duplicate]

Question

Background:

Over here on this forum for English speakers learning Chinese, there is debate on which ones among the following are correct English:

• the fruit is
• the fruits are
• the fruit are *?

Other questions on this site are about the regular mass noun (the fruit is) vs the regular count noun (the fruit are), but using the singular form "fruit" also as the plural form is only tangentially touched on once that I can see. I'm looking for a canonical answer on this specific point.

Do dictionaries, English grammars, or style guides list "fruit" as its own plural? Is it considered correct or incorrect?

If it's a nonstandard usage, where is it used? American English? Just some areas? It sounds wrong to me as a native Australian English speaker.

Is it correct to say "two fruit"?

Answer 1

Using Google Ngram Viewer and the search terms the fruit are,the fruit is,the fruits are, and then choosing the first quote, taken from a recently published book by a native speaking author, we have

1. The Woody Plant Seed Manual - Page 473

United States. Forest Service, ‎F. T. Bonner, ‎Robert P. Karrfalt - 2008 Found inside – Page 473

The fruits are juicy , 1- to 10 - seeded berries with enlarged , persistent calyxes at the base ( LHBH 1976 ).

2. United States Plant Patents - Page 18 United States. Patent and Trademark Office - 2008

The size of the fruit is large or similar to the size of the fruit of Mutzu. The ratio of height ..

3. The Encyclopedia of Fruit and Nuts - 2008 edited by Jules Janick, Robert E. Paull Found inside – Page 161 Very commonly, the fruit are covered with a waxy bloom.

The inescapable conclusion is that all are correct in context.

[20200924 - Example at 3. replaced by an example to include "fruit are"]

Answer 2

Interesting. Regarding the third variant, I think of often-heard sentences such as "The fruit are over there on the counter", "Help yourself to the fruit", "The fruit are there for the taking", or "The fruit are not very good today" when people are talking of a collection of different types of fruit. The construction may well be a topic of heated and polarized grammatical discussion but I realize that this usage is more common than I thought on first reading the question.