Sometimes, there aren’t just straight lines in plants. The second picture has a plant where there is a clear pattern of lines amongst the leaves of the plant. Sometimes, leaves can have no lined pattern, one lined pattern, or many lined patterns. The contrast, however, makes it really hard to miss the beautiful lined pattern.
I found this video, here, to go into detail about plant leaves and lines a bit more. Enjoy!
Where do you see lines in plants?