Box plots of two quantitative characters, leaf length (A) and leaf width (B), of Premna grandipaniculata, P. bracteata and P. interrupta. The boxes (rectangle region) represent the interquartile range and the whiskers (vertical line) represent the range excluding the outliers (circles). The three upper, middle and lower lines on the boxes represent the 75%, 50% and 25% of the variables, respectively. The upper and lower ends of the whiskers represent the maximum and minimum values of the variables, respectively. The circles represent the single value, where the variable value exceeds 1.5 times the difference between the 75% and 25%.