Friday, January 23, 2015

South Africa 4. The Incredible Pelargoniums

Pelargonium incrassatum provides brilliant
color in the northern Namaqualand region of 

South Africa.  Notice the characteristic 
stork's-bill fruits developing in this specimen.

 Pelargoniums are extremely popular garden and pot flowers around the world. They are planted in the cool season in Florida, and in the summer in the north.  They are often mistakenly called Geraniums, stemming from the fact that they were once in the same genus. You saw the difference in Part 3 of this series.  Geraniums, mostly dark blue or purple in South Africa, are radially symmetrical (petals all the same size and shape), while Pelargoniums are mostly bilaterally symmetrical, with an upper group of petals different from a lower group.

In any case, the genus Pelargonium has exploded in southern Africa, with over 200 species.  Only a few species occur elsewhere,including some in Australia and southwestern Asia. Most of the cultivated Pelargoniums are derived from just a few wild ancestors, and the other species are rarely seen in Amerian or European gardens.  So a trip to Sourh Africa in the springtime can be a real eye-opener.
Pelargonium peltatum is the source of cultivated "Ivy geraniums," which are neither ivy nor
geraniums.  This  vining species is commonly found growing among shrubs in coastal areas.

The diversity of flower form and color in Pelargonium reflects a spectacular array of pollination mechanisms, including much convergence (Struck & van der Walt, 1996).  This makes the classification and identification of species difficult.  The species also show a wide range of habitat preferences and include shrubs, vines, geophytes (bulb-like perennials), and spiny xerophytes (adapted to arid climates), with every imaginable form of leaf.  I have taken a stab at identifying the many species I saw in South Africa, but have only been partially successful. So I appeal to any South African readers to provide any assistance they can.

Several species have already been pictured in my previous posts, including the bright red Pelargonium fulgidum, and the common P. cordifolium. Here are a number of additional species, some identified and some not.
Pelargonium echinatum i a succulent species, with  bright magenta flowers with distinctive darker blotches on the petals, though apparently a white form is more common. The flowers of this species are nearly radially symmetrical, but like most members of the genus the upper two are larger, and the blotches of a different shape.
This appears to be a form of Pelargonium triste,  a geophyte with
a basal cluster of compound leaves
and a long stalk bearing an umbel of flowers.
Pelargonium crithmifolium has deeply divided

Pelargonium zonale, with familiar roundih, scalloped
leaves, is an ancestor of  the most common cultivars
(along with P. inquinans, P. scandens, and P. frutetorum).
An unidentified shrubby Pelargonium in the dry north
has managed to squeeze out a pair of flowers.

Pelargonium capitatum is a fragrant species,
and one of the commercial sources of
pelargonium or geranium oil.

An unidentified species from the west coast has odd leaves consisting of a
small, spade-shaped blade at the end of a very long petiole.
An unidentified species with small, reddish leaves,
 from the dry north along the west coast.
Pelargonium spinosum is a resident of the inland desert region of South Africa.
It drops its small leaves during the dry season and behaves like a cactus.

Key, Hazel, 2000. 1001 Pelargoniums. B. T. Batsford. London.

Webb, William J. 1984. The Pelargonium family: the species of Pelargonium, Monsonia, and Sarcoculon. Croom Helm, Dover, NH.

Struck & van der Walt, 1996, in van der Maesen, L. J. G. et al., The biodiversity of African Plants. pp. 631-638. Kluwer Academic Publishers. Springer Netherlands.