Display parsed XML in data frame

I have a function whose aim is to parse any XML data (using Duncan Temple Lang's XML package) given to it and produce output in a data.frame as shown in the desired output below. The getValues function is meant to produce list of attribute names and its associated values which then get passed into a data frame when called. But it doesn't work that way as not all attribute names and values appear in the data frame. Please see below for sample XML and the output I am currently getting.

library(XML)

getValues <- function(x) {
    aList <- list()

    #attributes
    if(!is.null(xmlAttrs(x))) {
        num.attributes = xmlSize(xmlAttrs(x))
        for (i in seq_len(num.attributes)) {      
            attributeName <- names(xmlAttrs(x)[i])
            attributeValue <- xmlAttrs(x)[[i]]         
            aList <- append(aList, c(Name = attributeName, Text = attributeValue))
        }
    }
    return(aList)
}

retrieveStructureInfo <- function(node) {  
    if (is.null(node)) {
        return()
    }

    nkids <- xmlSize(node)

    bypass <- function(n = nkids) {
        if(nkids == 0) {
           xpathApply(xmlParent(node), path = xpath, fun = getValues)
        } else {
           return(nkids)
        }
    }

    #children is the no. of nodes within a node
    for (i in 1 : children) {
      #recursive function call
      retrieveStructureInfo(node[[i]]) 
    }
}

#parse xml document
#xmlfile is the file path
doc <- xmlParse(xmlfile)
r <- xmlRoot(doc)
data <- data.frame(node = NA, value = NA)
retrieveStructureInfo(r)
data

Sample XML:

<CATALOG>
   <PLANT>
      <COMMON Source="a" Available="false">Bloodroot</COMMON>
      <LOCATION></LOCATION>
      <PARENT />
   </PLANT>
   <PLANT>
      <COMMON Source="b" Available="true">Columbine</COMMON>
      <LOCATION>Africa</LOCATION>
      <PARENT />
   </PLANT>
</CATALOG>

Output:

                  node       value
                source           a
                source           b

Desired Output:

                  node       value
                source           a
             available       false
                source           b
             available        true