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THE OTHER ZONAL PELARGONIUMS – 4. BIRD’S EGG-FLOWERED PELARGONIUMS

By Wayne Handlos, Ph.D

                                  cultivar    ‘Jay’s Golden Bird’s Egg’

                                                                                   

   flower     &      leaf               microscopic image of glandular hair*          petal

                                                with pigmented cells at its base from 

                                                 petal of ‘Jay’s Golden Bird’s Egg

                           double flower of cultivar ‘Plenty

The Bird’s Egg-Flowered pelargoniums have small colored dots on the upper side of the petals.

The three lower petals have more spots than the upper two petals. Each spot is associated with a

glandular trichome on the petal. Trichomes on the lower epidermis of the petals are not associated

with colored spots.

Studies by Almouslem and Tilney-Bassett (1989) have shown that the spots are of simple one-gene,

 genetic inheritance and that the allele controlling the red spots is dominant. The gene has been

named Rst and its recessive allele is rst. (HortScience 24:501-502) If you make a cross using a bird’s

egg cultivar as a parent, at least half of the offspring should have bird’s egg spotted petals.

In Europe, bird’s egg cultivars are grouped with other plants with speckled and striped petals in a

category of "egg shell" pelargoniums. While this is convenient, the plants are easily distinguished

and represent quite different genetic systems. Bird’s egg varieties have discrete round spots localized

near the center of the flower. The other speckled and striped types have irregularly shaped spots and

stripes randomly distributed over the surface of the petals. Genetically, according to Tilney-Bassett,

there are at least two different gene systems at work here. The striped and speckled cultivars, variously

called New Life or Paint box types, will be covered in a later article/newsletter. The origin of the bird’s-

egg characteristic among the zonal pelargoniums is obscure. Some believe they have been around since

the middle of the 19th century. They have been definitively around since the last years of the 19th century

and were well illustrated in Peter Henderson’s catalog in 1901.

Henderson was a well-known nursery- and seeds-man in the US and introduced many plants from Europe in the

late 1800’s and early 1900’s. These plants were probably most popular at their introduction. This may be due

to their novel appearance and the fact that some of them bloomed under low light intensity (i.e. the winter). In all

other aspects they are typical zonal ‘geraniums’. Some cultivars have gold-colored leaves but most have normal

green leaves. While bird’s egg cultivars were more popular in the past, only a few are grown today. These include

‘Jay’s Golden Bird’s Egg’, ‘White Bird’s Egg’, ‘Double Pink Bird’s Egg’, ‘Mrs. J.J. Knight’ and ‘Plenty’.

 

© 2015, Central Coast Geranium Society (CCGS )