why is the closing curly bracket here?

I’m trying to figure out how to display the latest instance in each of 3 categories on the index page, am not getting answers to my questions here, and am slowly stumbling my way through the Codex, and now have a question about one of the examples.

<?php if (is_category('11') ):
 // we're in the Plants category, so show a plant ?>
 <img src='/images/plant.png' alt='a plant' />
<?php } elseif (is_category('22') ):
 // we're in the Flowers category, so show a flower ?>
 <img src='/images/flower.png' alt='a pretty flower' />
<?php endif; // end the if, no images for other other categories ?>

Line 4 has a closing curly bracket that prompts an error when I put the snippet in my index template.
Why is the closing curly bracket there?
What does it do?

I took it out, the error goes away, I seem to have fixed a subsidiary problem, and might then be able to get back to my main question.