The last few weeks have been a time of looking closely at flowers, and marvelling at their variety. I observed about 12 types of pink flowers, about 8-10 types of orange flowers, about 5-6 red, a few yellow ones, a few white ones and two types each of purple flowers and blue flowers–all in my colony.
So of course the question came to my mind: Was this the typical distribution of flower colours? Was pink the predominant colour, followed by orange and red? And so started my search to find out a little more about this.
First and foremost, what gives flowers their colours? Colours mainly come from the presence of pigments in the chromoplasts or cell vacuoles of floral tissues. The most common pigments in flowers come in the form of anthocyanins which range in colour from white to red to blue to yellow to purple and to even black and brown. The other major group are the carotenoids, which provide the yellow colours, along with some oranges and reds. While many flowers get their colours from either anthocyanins or carotenoids, there are some that can get their colours from a combination of the two. Other classes of pigments, but of less importance in relation to flower pigmentation, are chlorophylls (greens), quinones (occasional reds and yellows), and betalain alkaloids (giving yellow, red and purple).
Coming back to which is the most common flower colour, all my web- searching only told me that there was no definitive answer! To begin with, we don’t even know how many flowering plants there are. And of the flowers we know and have catalogued, colour data are seldom maintained. There is no repository of flower colour information. There is no database which documents flower colours, let alone rank them.
There are many good reasons that make it difficult to document these colours. There is no absolute measure. Colours look different in different lights, at different times of the day. Each person perceives colour differently—what looks orange to me look yellow to you. And we all describe them differently—I may say violet for a colour and you may say mauve.
Moreover, colours vary from genus to genus, and even within a species. A plant growing in one area (say, the plains) can have flowers that are very different from the same plant growing elsewhere (say in higher altitudes). The colours of flowers depend very much on the growing conditions—soil, sunlight etc. So they may change somewhat with season too.
Recent research suggests that factors like ozone depletion and global warming have caused flowers to change their colours over time. For instance, of the 42 species studied in that research, UV-pigmentation in flowers increased at a rate of 2% per year from 1941 to 2017.
Flowers also use colours as signalling mechanisms. Some flowers change their colour once they are pollinated, so that bees do not come back to them, but rather go to unpollinated flowers. (Eminent teacher, Prof. Mohan Ram, who developed a generation of botanists, ecologists and environmentalists, taught us this during a memorable nature walk.) Some flowers change their colour with age.
But here are some speculations about flower colours:
Counter-intuitively, some people believe green may actually be the most common flower colour–many plants, including most trees, bear flowers in various shades of green. This may be followed by white, yellow, blue and the reds in that order. Brown is not uncommon either. But all scientists and naturalists emphasize that these are only guesses.
So don’t worry too much about how many. Just enjoy the flowers and their colours!