def harvesttree(textfile=''):
filename, description = treedescription()
tree = TTree('tree', 'data from ascii file')
if len(textfile) > 0:
nlines = tree.ReadFile(textfile, description)
elif len(filename) > 0:
nlines = tree.ReadFile(filename, description)
else:
print 'WARNING: file name is empty. No tree is read.'
tree.SetMarkerStyle(8)
tree.SetMarkerSize(0.5)
return tree