LaTeX top row on a stem and leaf plot table

I am trying to represent a stem and leaf plot in a tabular environment in LaTeX using the following:

\begin{table}[htbp]
  \centering
  \caption{Stem Plot of sit ups, Key: $1 | 1= 1.1$}
    \begin{tabular}{r|l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}}
   \multirow{2}{*}{} Stem & Leaf     \\
    \hline
    1     &开发者_Go百科; 1     & 1     & 2     & 3     & 3     & 4     & 4     &       &  \\    
    1     & 5     & 6     & 6     & 8     &       &       &       &       &  \\    
    2     & 0     & 3     &       &       &       &       &       &       &  \\    
    2     & 7     & 8     &       &       &       &       &       &       &  \\    
    3     &       &       &       &       &       &       &       &       &  \\    
    3     & 5     & 7     & 8     & 8     &       &       &       &       &  \\
    4     & 0     & 0     & 0     & 1     & 2     & 4     & 4     & 4     &  \\
    4     & 5     & 5     & 6     & 7     & 7     & 7     & 8     & 8     & 9 \\
    \end{tabular}
  \label{tab:addlabel}

\end{table}

But when I do this, the 2nd column has is too wide and there is a gap between the 2nd and 3rd column of leaf values. How can I make it so that the 'Leaf' cell overlaps into the next column or somehow remove the gap?

You can put Leaf into a \multicolumn{9}{l}{Leaf}. The number (9 here) gives how many columns that should span, the l gives the formatting of the cell. If you need a right bar, you have to use l| there, by the way.

You do not need the \multirow then, I think.

\begin{table}[htbp]
\centering
\caption{Stem Plot of sit ups, Key: $1 | 1= 1.1$}
\begin{tabular}{r|l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}l@{\hspace{4 pt}}}
   Stem & Leaf     \\
    \hline
    1     & 1 1 2 3 3 4 4\\    
    1     & 5 6 6 8\\    
    2     & 0 3\\    
    2     & 7 8\\    
    3     &\\    
    3     & 5 7 8 8\\
    4     & 0 0 0 1 2 4 4 4\\
    4     & 5 5 6 7 7 7 8 8 9 \\
    \end{tabular}
  \label{tab:addlabel}

\end{table}

\multirow and \multicolumn somehow mess up the first row when used.