Adding header lines to a dataframe that is exported using write.csv

I would like to export a dataframe to a .csv using:

write.csv(dataframe,"dataframe.csv")

but I need to add four "header" lines to the csv that are not part of
the dataframe (which itself has a line of column headers).

The difficulty (for me, at least!) lies in the requirement that
certain elements of the header (X, Y and the number of "Q"s - please
see example below) must be defined based on the number of rows and
columns in the dataframe, which vary depending on the input file.

Here's what the 3 .csv header lines should look like, followed by a
number of dataframe rows (i.e., these lines are not R code, but are
what R will produce).

X, plots ,,,, #where X=number of rows in the dataframe
Y, species,,,, #where Y=number of columns in the dataframe
,Q,Q,Q,Q,Q #where the number of Qs=the number of columns in the dataframe

Those 3 .csv header lines would be followed by dataframe, which
consists of one row containing column headers and X "data" rows:

,spec1,spec2,spec3,sp3c4,spec5 #these are the dataframe's column headers
plot1,15.84,0,0,792,7 #this is an example "data" row

In case the above is unclear, I have also attached a small .csv as an
example of what the output should look like.

Thank you. Mark