[xml] 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

for $d in $doc/element2/element3 return fn:string-join(fn:data($d/element()), ".").
$doc stores the Xml.

<xsl:template match="element3">
        <xsl:value-of select="element4,element5" separator="."/>
    </xsl:template>

If you need to join xpath-selected text nodes but can not use string-join (when you are stuck with XSL 1.0) this might help:

<xsl:variable name="x">
    <xsl:apply-templates select="..." mode="string-join-mode"/>
</xsl:variable>
joined and normalized: <xsl:value-of select="normalize-space($x)"/>

<xsl:template match="*" mode="string-join-mode">
    <xsl:apply-templates mode="string-join-mode"/>
</xsl:template>    

<xsl:template match="text()" mode="string-join-mode">
    <xsl:value-of select="."/>
</xsl:template>    

I used concat method and works well.

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

Here comes a solution with XSLT:

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="//element3">
    <xsl:value-of select="element4/text()" />.<xsl:value-of select="element5/text()" />
</xsl:template>
</xsl:stylesheet>