By Wayne Handlos, Ph.D.

1. 2.   3. 4. 5.

1. &2. Apple Blossom Rosebud  3., 4. 'Magenta Rosebud' flowers & 5. leaf

        An increase in the number of petals beyond the basic number (usually 5) has been appealing

to gardeners for many years (decades, centuries). The appearance of "double" flowers usually

means an increase in the number of brightly colored petals in a flower – the "more is better"

philosophy. In many plants the increased number of petals is correlated with an increased life

span for the flowers. Doubleness is frequently tied to sterility so no (unsightly) seed pods are

formed (therefore no deadheading). Many plants stop blooming when seed pods/fruits are ripen-

ing so double flowers may also mean a longer flowering season for such plants. The sterility of

double flowers results when stamens and pistils are replaced by petals.

        In western society we have been aware of double flowers since Theophrastus mentioned double-

flowered roses in his Enquiry into Plants written about 300 B.C.

"Among roses there are many differences, in the number of petals, in roughness, in beauty of colour, and in sweetness

of scent. Most have five petals, but some have twelve or twenty, and some a great many more than these; for there are

some, they say, which are even called 'hundred petalled’. Most of such roses grow near Philippi; for the people of that

place get them on Mount Pangaeus, where they are abundant, and plant them. However the inner petals are very small

the way in which they are produced being such that some are outside, some inside)." THEOPHRASTUS –

ENQUIRY INTO PLANTS … Written between 350BC and 287BC. Translation

by Arthur Hort, 1916, v. 2, Book 6, page 39.

6. 7. 8. 9. 10.

6.&7. Dodoens-16th C.       8.'Gloire de Nancy'

9.Rosebud w/ extra sepals   10. Rosebud flower w/ 53 perianth parts

        R. Dodoens (Flemish physician-botanist) illustrated double roses, carnations and butter-

cups in his works from the mid 1500’s.

        One often reads about the first double zonal Pelargonium. Credit is usually given to

Victor Lemoine for his ‘Gloire de Nancy’ in 1864. Lemoine was a very successful nurseryman

/plant breeder, who did make important contributions to the horticultural world with the

introduction of a great diversity of ornamental plants over his long career. He developed

many cultivars of zonal Pelargoniums – including many double-flowered forms. However,

a search of the records of plant collections and botanic gardens reveals the presence of

double-flowered Pelargoniums well before 1864.

        Page’s Botanic Garden in Southampton, England, in 1818 lists many species and

varieties of Geranium (mostly Pelargonium species). On p. 139 of his Prodromus … he

lists G. inquinans with two varieties fulgens (dark red) and flo:pleno – double flowered.

In Latin flo.pleno and are abbreviations for flore pleno meaning "with full flower".

On p. 140, Page lists G. zonale with the varieties: alba (white), carnea (flesh colored),

coccinea (scarlet), monstosum (monstrous), pleno (double), fol.margina. (striped edged),

fol.var.aur. (gold striped), fol.var.arg. (silver striped), fol. tricolor (three color leafed).

[Page’s Latin and English names.]        

      Our obscure Pelargonium expert, Jakob von Reider noted double Pelargoniums in

three of his publications. Unfortunately none were illustrated. In vol. 2 (1827) of his

Annalen der Blumisterei …, on page 108 he listed Pelargonium zonale flore pleno with

9-10 petals. In 1829 in his Beschreibung aller bekannten Pelargonien … (Description of

all known Pelargoniums) on page 379 he described Pelargonium zonale flore pleno with

"7-9 auch [also] 10 Blümenblätter" (petals) and on page 382 he listed a variety "(f) mit

gefüllten Blumen" (with full or double blossoms). Also in 1929 in his book Abbildung

von fünf und zwanzig und beschreibung von hundert des neuesten und merkwürdigsten

Pelargonien (Illustrations of 25 and description of 100 of the newest and most noteworthy

Pelargoniums) on page 52 he described Pelargonium inquinans flore pleno incarnata

with 9-10 petals.

        Patrick Niell wrote in his Journal of a trip through Flanders, Holland and France in

1817 that "an orna-mental variety of Pelargonium inquinans, with double flowers is very

 common at Ghent." So while more modern writers gush lovingly about the new and unique

double-flowered Pelargoniums of the 1860’s and 70’s, double-flowered Pelargoniums had

already been in existence for at least 50 years. So much for romance and publicity.

        Yet, there might be some underlying reality in all of this. Again Tilney-Bassett and his

students come to the rescue. On the basis of their definitions, a single flower has 5 sepals

and 5 or 6 petals (10-11 parts); a semi-double flower has 5 or 6 sepals and 7-15 petals

(12-21 parts); double flowers have 21 to 30 perianth parts (sepals and petals combined);

41 to 60 perianth segments would be considered "a real rosebud cultivar."

11.  12. 13. 14. 15.

11. Apical meristem    12.&13. 'Orange Bud  flower & leaf    14.'Jewel'       15.'Apricot Queen'

        When flowers are formed from an apical meristem the flower parts originate as whorls of

bumps from the meristem. The first whorl normally develops into 5 sepals, the second inner

whorl develops into 5 petals, the next inner set of parts are stamens and the last group of

parts form the 5 carpels. In double or semi-double flowers, the genetic controls are disrupted

and the second and third whorls of parts develop into petals (rather than petals and stamens).

In another scenario additional whorls of parts are initiated which develop into sepals and petals

giving the more fully double and rosebud flowers.

        Tilney-Bassett (Variegated Zonal Pelargoniums) and his students have determined that the

single flower (5 sepals, 5 petals etc.) is controlled by a gene D. A single-flowered plant has

the recessive genotype: dd. If a plant has semi-double flowers, the dominant allele D is present.

They have found that the dominant allele, D, activates three modifying genes: M1, M2 and M3.

In their homozygous recessive form – m1m1 and m2m2 – each add 10 perianth parts to the

flower while m3m3 adds 20 perianth parts to the flowers. A semi-double flowered plant would

have the genotype Dd or DD M1- M2- M3-. A double-flowered plant would have the genotype

Dd or DD m1m1 M2- M3- but a very double rosebud flower would have the genotype Dd or DD

m1m1 m2m2 m3m3. On the basis of probability, the last combination is the least likely to occur,

hence the rarity of the rosebud-flowered plants.

        Using von Reider’s descriptions of 7-10 petals that would indicate a semi-double flower in his

flore pleno varieties. Using the illustrations of ‘Gloire de Nancy’ (the first double) we can count

about 16-20 petals (and assuming at least 5 sepals) that places this cultivar in the category of

double flowers. In the 1870’s a number of double flowered cultivars were illustrated. ‘Jewel’ has

been suggested as a rosebud-flowered variety. While the illustration is not totally clear, it would

appear to have a large number of petals and would probably qualify as a rosebud-flowered or

Noisette-flowered zonal Pelargonium. Noisette roses were many-petalled roses popular in

Victorian times with some cultivars still available today.

16.  17. 18.  19. 20.

16.&17. 'Rococo' (ivy-zonal hybrid) flower & leaf   18.&19. 'Golf Ball' flower & leaf

20. 'Spanish Lavender' 

        Double/semi-double flowers are commonly found in ivy geraniums. Using the Tilney-Bassett

categories several cultivars would qualify as rosebud-flowered ivies. Two P. cucullatum-related

cultivars have double flowers – ‘Golf Ball’ and ‘Spanish Lavender’.  While regal Pelargoniums

flowers frequently have one or two extra petals they do not normally reach the numbers to qualify

as semi-double flowers. Historically it appears that so-called "double-flowered regals" have very

ruffled petals giving the appearance of a double flower. But, counting the petals usually yields

the number 5 or 6. However, R. Sweet in his Geraniaceae, vol. 5, plates 81 and 86, illustrates two

regal-type varieties (P. Veitchianum, P. implicatum) with additional petals which would qualify

them as semi-doubles.

         In vol. 8, 1832, p. 285, of his Annalen … von Reider presented an illustration (‘Herzog

Wilhelm’) which shows flowers with a proliferation of petals from stamens. The Illustrirte

Garten-Zeitung for 1868 (vol. 12, taf. 3) illustrated a cultivar (‘Prince of Novelties’) with truly

double flowers. None of these cultivars seems to have lasted into modern times.

21. 22. 23. 24.

21.Trattinnick's P. montrosum  22.  Sweet's P. implicatum 23. 'Herzog Wilhelm'

24. 'Prince of Novelties'

© 2015, Central Coast Geranium Society (CCGS )