Cephalaria gigantea . Giant Yellow Scabious.
A magnificent sight in early summer with its large mound of roughly hairy, pale green, deeply pinnatifid foliage and 6ft branching stems generously furnished with 3in pale lemon flowers which sway in the slightest breeze. You can use Cephalaria at the back of any scheme or alternatively further forward as the flowering stems are not dense, allowing you to see through to sights beyond.
Flower structure in Scabious:
I thought I would write a small piece on the intricate flower structure that scabious exhibit with the tight pincushion centre and flamboyant outer petals. Each individual flower head is in fact a compound flower just like the daisies, being composed of a tight dome of individual florets. The flowers making up the central disc florets and those more showy outer ray florets are essentially the same, all are basically trumpet like tubes, its just that the outer ones develop more colour and have much more flamboyant petals. It’s a case of scaling rather than form. Within the disc, the male stamens are held close to the flowers throat whilst the female pistil projects well out giving the flower its pincushion form. The often contrasting colours of each flower type and the colours of the stamens and pistil are what make theses flowers so attractive. The flowers of Cephalaria, Knautia, Succisa and Succisella all follow a similar pattern, each with a decreasing emphasis on the large outer flowers.
If you look closely at the unopened flower you can see that the individual florets are arranged in two spirals, one to the right and one to the left. It is a characteristic that shows up better in some species than others. What is fascinating about these spirals is that the number of spirals each direction will be different and they will be found to be two adjacent numbers on the Fibonacci sequence. (ie 1,1,2,3,5,8,13,21,34 a sequence made up by adding the previous number each time). This is an adaptation that allows the most flowers to fit in a given space with the least gap. Its not the only place you can find the Fibonacci sequence in plants. Plants always have the same number of petals in their flowers and the numbers plants use are to be found on the Fibonacci sequence – Plants really can count.