MicrostockGroup

Rosa - rose
Tea - there is no tea
bouquet, bunch - everywhere is only one flower
shrub - bush may be better?

Also it's good to include the latin name...

What makes you think it is okay to have pink AND red as keywords for every picture regardless of the actual color of each rose?  Do you think Shutterstock should accept 'pink' as a keyword for a picture of a red rose?

Also, these are roses growing in a garden - the words bouquet, love, romantic etc do not apply.

Shutterstock are correct to reject your pictures.

In my opinion, in no way do these flower pics relate to Valentine. Cut one, put a ribbon on it, light it properly, and shoot in studio or equivalent. Then maybe I'll buy the valentine keyword.

Well, basically you aren't supposed to do that.  It's called keyword spamming and every site frowns on it.

Each image is supposed to be keyworded individually.  It's fine to cut and paste, but only as a starting point.  The irrelevant words have to be removed from the images they don't apply to, and relevant ones unique to that image should be added. 

FYI, if you want to use a compound word like Tea Rose, it's better to use tea-rose, so that the words are connected in the search, rather than separate, where tea has no relevance whatsoever.

I get the feeling from your post that you aren't really asking for suggestions, but more venting about the rejections.    Fine for getting out your frustrations, but if you are serious about getting images accepted you should pay attention to the advice in this thread because it is dead accurate. 

yes they do.
Every picture that is different in any case.

If the picture is of the same object but from a different angle the two image can share the same keywords, but if the image is of something different it should not contain the same keywords - unless all the keywords apply to the second image just as well.