Barleria obtusa Leaf Variation

My Barleria obtusa shrubs are doing some strange things. I bought three plants on the same day from one supplier and they looked identical. It’s now about 6 weeks since I planted them and I’ve noticed that one of the three plants looks different. The leaves are darker and bigger. Here’s a comparison with the leaves of the plants.

The odd one’s average leaf size is 8cm whilst the others are 3cm.  I initially thought that the nursery had mislabelled the sleeve, but it has the same flowers as the others. In fact, this odd one seems to have more flower buds than the other plants.  The only difference here could be the positioning of the plants. They are planted adjacent to each other with a 50cm gap between them. The odd one is ever so slightly in a more protected position and receives less direct sunshine.

This is something new to me as the books talk about Barleria obtusa being suitable for both semi-shade and full sun. It is going to be interesting to see how they grow. The shrub grows up to 75cm tall and mine are just 25cm at the moment.