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PELARGONIUMS IN SECTION RENIFORMIA

By Wayne Handlos, Ph.D.

                              

   Pelargonium abrotanifolium                    P. exstipulatum                       P. fragrans          P. 'Variegated Fragrans'

                          

P. odoratissimum                   P. ionidiflorum                                             P. sidoides                                     ' Ardwyck Cinnamon'

                                  

'San Jose Surprise'                                   'Lavender Lad'                                       ' Lavender Lass'                                                                                                           

  < Unnamed Seedling

The genus Pelargonium has been subdivided into a number of subgroups called sections. One of these sections, called “Reniformia”, is the subject of this article. Diana Miller in her book Pelargoniums recognizes at least nine species in this group including P. abrotanifolium, P. album, P. dichondrifolium, P. exstipulatum, P. fragrans, P. ionidiflorum, P. odoratissimum, P. reniforme and P. sidoides.

Plants in this section come from slightly wetter regions of South Africa and do not have the extreme dormant periods seen in species from the drier, more arid areas of South Africa. Most of the species in the section have scented foliage. The flowers are zygomorphic (bilaterally symmetrical) and have distinct right and left sides. The two upper petals are larger while the three lower petals are narrower and spreading. The basic chromosome number for the group is eight. Three of the species, P. ionidiflorum, P. reniforme and P. sidoides, have brightly colored or deeply pigmented flowers. All plants in this group are relatively easy to grow.

Pelargonium abrotanifolium is named for the shape and fragrance of its leaves. The leaves bear some resemblance in shape and fragrance to the leaves of Artemisia abrotanum also known as southernwood. The small, gray green leaves are deeply divided. The petals are white or light pink with reddish purple markings on the two upper petals. It is most similar to P. exstipulatum which has simple, gray green leaves. Pelargonium fragrans or P. x fragrans (or nutmeg geranium) is probably the most widely known and grown member of this section. The name “fragrans” refers to the strongly scented foliage which some believe smells like the spice nutmeg. This plant branches freely and tends to have a compact habit. The flowers are small and white. There are several named variegated forms of this plant which F. Brawner considers all the same and may even be found on the same plant. These cultivars are ‘Golden Nutmeg’, ‘Snowy or Showy Nutmeg’ and ‘Variegated Nutmeg’. (Other cultivars in this section will be considered later because of the difficulty in knowing their origins.)

Pelargonium odoratissimum – the apple scented geranium – is named for the very fragrant foliage which some people perceive as that of apple fruit. The leaves are rounded and light green in color. The flowers are white and small. When this plant flowers, it may become very untidy looking with its long flowering stalks. There are several named cultivars associated with this species but they will be described later.

Pelargonium ionidiflorum (imaginatively called the celery geranium since the leaves have essentially no odor) has bright pink flowers and is distinct in that regard among the plants in this group. The name “ionidiflorum” means violet colored flower. These plants have broad leaves which are deeply toothed or lobed. These plants make a nice show when in flower in a pot or window box.

Pelargonium sidoides has also found its way into the commercial trade. It is easy to recognize because of the deep purple-black flowers. The leaves of this species are also roundish and gray green with a silvery sheen. The species name means “looking like Sida” referring to the leaves which are gray green and round like those of a plant in the genus Sida. It produces thick fleshy roots which are harvested and made into cough syrup . A similar species, after which this section is named, is P. reniforme. The word “reniforme” means kidney-shaped and described the outline of the leaves. The flowers of this species are bright pink to magenta but not as bright as P. ionidiflorum. Two forms of this species are recognized – one with long trailing stems, the other more compact and bushy with a short upright stem.

Another species in this group, referred to as the Black Pepper Geranium, is P. dichondrifolium. This name describes the leaves as looking like Dichondra which some may know as a ground cover or lawn substitute. Its flowers are white. It is characterized as have very long (to 4”) persistent petioles.

The last species in this group is P. album which produces large (to 3”) leaves which are sticky and aromatic. The flowers are white as indicated by the name “album”.

There are a number of named cultivars which are clearly derived from species in this section. Some of these may just be variants of their respective species but others are known or suspected hybrids between species in this group. Therefore they are dealt with here as groups based on their scents.

Apple scented cultivars include ‘Apple Cider’, ‘The Big Apple’, ‘Cook’s Apple Cider’, ‘Aroma’ and ‘Fringed Apple’.

‘Burgundy’ is a cultivar which is very similar to P. sidoides but it may be a hybrid between that species and P. reniforme.

Spicy scented cultivars include ‘Curly’, ‘Isobel Eden’, ‘Ardwyck Cinnamon’, ‘Old Spice’, ‘Tutti Frutti’, and ‘Joanne’s Spring Clover’. ‘Lilian Pottinger’ (camphor scented) and ‘Pine’ bear resemblances to P. fragrans as do all of the other plants in this group.

More recently produced cultivars include ‘Lavender Lad’, Lavender Lass’, ‘Lilac Lady’, ‘San Jose Surprise’ and an unnamed seedling from my garden. These cultivars are variously scented and are believed to be derived from P. ionidiflorum crossed with various other species.

Whatever their origins, here is a group of “scented leaf geraniums” that are generally neat and tidy, may produce some bright colored flowers and enliven our environment with some intriguing scents.

Why do the leaves of P. fragrans smell like nutmeg? The main chemical components of nutmeg oil (derived from the nutmeg spice from Myristica fragrans, the nutmeg tree) are pinene (20%), sabinene/camphene (50%), limonene (8%), linalool (6%), borneol (6%), terpineol (6%), geraniol (6%), methyl eugenol (2%) and myristicin (4%). The major chemical constituents of the essential oil extracted from the leaves of Pelargonium fragrans are a-pinene (20%), methyl eugenol (10%), alpha thujene (10%) (similar to camphene/sabinene), fenchone (8%), limonene (7.5%). So, there is a chemical similarity for calling P. fragrans the nutmeg geranium.

Is P. fragrans a species? Pelargonium fragrans is not known in the wild so there is a question as to its origin and its status as a species. It has been proposed that it is a hybrid between P. exstipulatum and P. odoratissimum. Attempts to cross these two species have not been very successful to recreate a documented hybrid that resembles P. fragrans. If this had been done then we would be fairly certain that P. fragrans was of hybrid origin and we would refer to it as P. x fragrans; the “x” being the correct way of referring to a hybrid. Lis-Balchan et al. have approached the question of origin in a different fashion. She and others have analyzed the composition of the essential oils produced by the three taxa. These studies show that the amount of the different essential oils of P. fragrans is intermediate between those of P. odoratissimum and P. exstipulatum. These facts are taken as evidence that P. fragrans could be of hybrid origin.

                                                                                                                                                                October 2009

          

© 2010, Central Coast Geranium Society (CCGS )