THE OTHER ZONAL PELARGONIUMS – 3. CARNATION-FLOWERED PELARGONIUMS
By Wayne Handlos, Ph.D.
Carnation-flowered pelargoniums are characterized by flowers with petals having a fringed or toothed margin –
similar to what you see in carnations.
This characteristic of petals was documented by William Bateson (a famous geneticist) in a publication in 1921.
He said that the salmon-fringed pelargonium was bred by a nurseryman, Mr. Jarman of Chard, Somerset, England.
This plant has been named ‘Salmon-fringed’, ‘Skelly’s Pride’ or ‘Jeanne’. It has distinctive "crumpled", glossy leaves
and sterile flowers. Plants developing from root cuttings or an occasional side branch have normal petals, flat, matte
leaves and fertile or perfect flowers. These cultivars are notoriously unstable, meaning the petals lose the dentate
characteristic and revert of plain petals. Both Bateson and Chittenden (1921, 1925/6) have clearly explained these
features of the carnation-flowered cultivars and their instability. Most (or all) of the cultivars with fringed or carnation
-type flowers are likely to "sport" and produce ordinary flowers without any toothing of the petals.
The explanation is simple enough. These plants are periclinal chimeras. (See article/chapter on Chimeras.) Studies on
variegated leaved or fancy-leavedPelargoniums were basic to the understanding of leaf variegation in particular and
plant growth in general as described by Baur as early as 1908. In the three cell layers of the plant’s apex, the outermost
layer carries the genetic trait for toothed petals and glossy leaves. The inner layers of the apex are genetically different
(normal) and plants developing from these cells produce plain, fertile flowers and ordinary leaves. If the outermost
layer of cells is replaced by the inner layer, the genetic information for these special carnation-flowered petals and
glossy leaves is lost. Strictly speaking, this is not a mutation or a change in the DNA, it is akin to a mechanical change
in position of cells in the apex – so that the innermost cells with a different genetic composition get a chance to express
their genetic capabilities. It has been noted that once a plant has "reverted" to a normal type, the unusual floral (or leaf)
characteristics do not return and this is explained by the fact that once the outer layer of cells in the apex is replaced,
they have nowhere from which to reappear.
For reasons which escape me, this understanding of the basic nature and biology ofPelargonium has been overlooked
by geranium growers and fanciers since the early 1900’s. In more recent times, this phenomenon has been described at
length by Richard Tilney-Bassett in his two books: Plant Chimeras (1986, 199 pp.) and Variegated Zonal Pelargoniums
(2008, 252 pp.).
Chimeral structure in plants explains many phenomena in Pelargonium – "sporting" or "reversion" of variegated leaves
to all green or to albino or all white leaves; loss of the tulip-shaped flowers; loss of shiny leaves; loss of sterile flowers;
changes in flower colors; ‘Mr. Wren’s’ distinctive flower pattern; white-flowered plants breeding as if they were scarlet
flowered, etc. In addition to the carnation-flowered cultivars mentioned earlier, other carnation-flowered zonals have been
cultivated – ‘Madame Thibaut’ is a single, carnation-flowered plant with white or pinkish flowers with pinkish veins,
‘Diana Palmer’ which is a double flowered type with salmon colored flowers and ‘Lancastrian’ a double, rosy-salmon,
carnation-flowered cultivar available in Europe.Some years ago a popular line of zonals, the Fiats, had several cultivars
with toothed petals. They were also unstable and frequently reverted to a plain petalled form. They are not commercially
available any longer. A few new cultivars of zonalPelargoniums with fringed petals have been developed more recently,
including ‘Era’s Silva’, ‘Bockens Killing’, Karin Lundh Hansen’s types ‘Elnaryd Annelie’ and ‘Elnaryd Ljuvliga Julia’.
These are available from specialist growers in Europe. Carnation-flowered plants are found in the ivy category also;
namely ‘Pink Carnation’ and ‘Cerise Carnation’. They are both found to be unstable and the production of fringed petals
is lost frequently. Cliff Blackman from Australia in his search for a yellow-flowered Pelargonium began a breeding program
involving the species P. articulatum, the zonal cultivar ‘Princess Fiat’, the ivy/zonal hybrids ‘Alliance’ and ‘Millfield Gem’.
A distinctive group of hybrids and cultivars wasdeveloped from this program which he named ZONARTICS using part of
the words "zonal" and "articulatum". ‘Princess Fiat’ hadfringed or carnation-flowered petals and presumably has passed
this trait along to some of the zonartics. Cf. ‘LaraMandarin’, ‘Lara Blush’, ‘Unicorn Zonartic Rose’, ‘Unicorn Vanilla Sky’,
‘Unicorn Zonartic Hot Butter’. Information from MikeBrown (Floraberry Nursery) in Australia suggests that the toothed
petals are stable in the Zonartic plants that he hasgrown. Unfortunately, because of government regulations to prevent
the introduction of plant diseases, these plants have not been brought into and are not available in the US.