Concatenate multiple node values in xpath

I have a XML that looks like this

<element1>
    <element2>
        <element3>    
            <element4>Hello</element4>
            <element5>World</element5>
        </element3>
        <element3>    
            <element4>Hello2</element4>
            <element5>World2</element5>
        </element3>
        <element3>    
            <element4>Hello3</element4>
            <element5>World3</element5>
        </element3>
    </element2>
</element1>

I am trying to use Xpath to get a result like this:

Hello.World
Hello2.World2
Hello3.World3

I used concat function below but I did not get correct result.

Concat function:

concat(/element1/element2/element3/element4/text(),".", /element1/element2/element3/element5/text())

Result I got:

Hello.World

How can I get the correct result? I am using XPath with Camel Spring DSL.

Edit:

Solutions in XQuery, XSLT and SPel are also appreciated.

Edit

I tried string-join and it did not work:

string-join function:

string-join((/element1/element2/element3/element4/text(), /element1/element2/element3/element5/text()),".")

Result I got:

Hello.Hello2.Hello3.World.World2.World3

Try this expression...

string-join(//element3/(concat(element4/text(), '.', element5/text())), "
")

I used concat method and works well.

concat(//SomeElement/text(),'_',//OtherElement/text())