Overcoming Loss of Vigor in Cornflower Blue Cineraria (Pericallis x hybrid) at Longwood Gardens

by Jim Harbage, Alan Petravich, Robert Armstrong and Matt Taylor

‘Cornflower Blue’ cineraria Pericallis x hybrida (formerly Senecio x hybridus) is an annual plant that is difficult to propagate asexually.  For many years, this plant has been a traditional crop in the late winter/early spring display of Longwood Gardens’.  Seed of this strain was being obtained from a commercial source, which has discontinued the distribution of this crop. Since this was the only source, it fell upon Longwood to maintain its own seed supply.  At first seed was produced by simply self pollinating the plants and collecting the seed.  It was soon discovered that the vigor of the resulting plants was being rapidly reduced with each generation. It was decided that if this highly desirable crop were to continue at Longwood, drastic measures would need to be taken.  To this end, in 1995 two Longwood staff members were sent to the Canary Islands to collect seed of native Senecio (cineraria) species.

The seed brought back was Senecio papyraceus , which is tall-growing with small rose-colored flowers.  This species was crossed with the ‘Cornflower Blue’ strain. The resulting F1 generation contained individuals with positive traits for height, canopy diameter, flower color, flower form, leaf size and shape that ranged between the two parents.  The populations also had individuals with white and very pale blue flowers, as well as ray petals that were blue in the distal portion and violet near the disk. 

From 1994 – 2001 populations of plants were continually back-crossed with the original 'Cornflower Blue' Cineraria aiming to stabilize the seed line for full sized cobalt blue petals, a large amount of flowers per plant, and plant height. These crosses were successful for many years until once again, inbreeding lead to a loss of plant vigor. Researchers at Longwood gardens have overcome this by growing specific strains of cineraria in tissue culture. By growing cineraria in sterile tissue culture, with strict environment controls, the plants can be maintained indefinitely. 

Once a year, the two ideal cineraria parents are brought out of tissue culture and traditionally grown to produce flowers. These plants are crossed to produce the seed stock for the following year. This seed will then produce the wonderful ‘Cornflower Blue’ cineraria that are always an eye catcher in our late winter/early spring display.