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IVY AND IVY-LEAFED GERANIUMS

BY WAYNE L. HANDLOS, Ph.D.

Pelargonium peltatum      Lillian      Mauve Beauty     Thornlands Marble     Vectis Cascade     Fringed Rouletta    Gay Baby

 Pelargonium peltatum           Lillian                     Mauve Beauty           T hornlands Marble         Vectis Cascade          Fringed Rouletta            Gay Baby

  Bonito       Rio Grande      Pink Carnation     Big Red     Desrumeaux    Spotlight Hotline

               Bonito                       Rio Grande                 Pink Carnation                    Big Red                       Desrumeaux               Spotlight Hotline

 Artic Frost leaf     L'Elegante leaf     Lila Compacta leaf     Crocodile leaf

        Artic Frost                         L'Elegante                      Lila Compacta                      Crocodile

The ivy or ivy-leafed geraniums are trailing plants derived primarily from the species Pelargonium peltatum. The species name describes the attachment of the leaf stalk or petiole to the back of the leaf blade (somewhat like the handle of a shield). The species is native to South Africa. Plants of this species arrived in Holland from South Africa in 1700. By 1701 they were being grown in England.

The leaves of P. peltatum tend to be 5-lobed hence the superficial similarity to ivy leaves. True ivy (Hedera helix) belongs to an entirely different plant family (Araliaceae) so there is no close relationship between the two. The species P. peltatum is a trailing plant, with fleshy, 5-lobed, slightly scented leaves. The leaves often have a darker, brownish central zone. In the wild, there is variation in the petiole attachment to the leaf blade, the hairiness of the leaves and the depth of the leaf lobes. Very hairy-leafed forms of the ivy geranium have been named P. clypeatum. Those with petioles attached to the edge of the leaf have been named P. lateripes or P. hederinum. None of this variation is now believed to be related to distinct species and all of this variation is found within the single species P. peltatum. The flowers may be white, pink or lavender, up to almost 2 inches across. The upper two, larger petals have some darker veins, which the three lower, smaller petals lack. While photographing the ivy geraniums at a local nursery, I was struck by the amount of variation which could be found among the cultivars in their collection.

The flowers of ivy cultivars run the color gamut from white to pink to apricot to orange to scarlet to red to rosy red to dark burgundy. Veining or patterning in contrasting color may be prominent in the two upper petals or nonexistent. These colors are well represented in collections of the major breeders; Ball has the Colorcade series; Oglevee (Ecke) has the Global series, Fischer (Syngenta) has the Blizzard series and Pac has the Pacific series.

The number of petals varies among the various cultivars. The basic pattern is five petals. The Blizzard series has single flowers with five petals. Over the years semi-double and double forms have been selected, so that the most double forms now look like miniature, double rose blossoms. These include ‘Mauve Beauty’ and ‘Thornlands Marble’. Most currently commercially available cultivars are semidouble to double in form and include the series named above. While the flowers of P. peltatum are strongly zygomorphic (bilaterally symmetrical with two larger and three smaller petals), some cultivars have actinomorphic flowers (all petals are of similar size and shape and are arranged symmetrically around a central axis). ‘Vectis Cascade’ is such a single flowered cultivar. Most of the semidouble and double cultivars tend toward radially symmetrical flowers.

Some varieties of ivy geraniums show variegated flowers. The center of the petal is white while the edge of the petal shows the color. The first variety to show this pattern was ‘Rouletta’ (called ‘Mexikanerin’ in Europe) and it was derived from ‘Mexican Beauty’ in Mexico in the 1960s. This pattern has been found to be due to a (benign) virus infection. This virus can be spread from plant to plant by grafting. “New” varieties of ivy geraniums are developed by transferring this virus to existing cultivars by grafting.

Two-toned flowers are also found in some cultivars. In these the edge of the petals is lighter in color as in ‘Bonito’ or the back of the petals may be lighter as in ‘Rio Grande’.

The size of the flowers is variable too, ranging from the large, single ‘Big Red’ to the tiny white ‘Gay Baby’. In ‘Spotlight Hotline’ and ‘Baton Rouge’ the petals are very narrow.

While we expect to see extreme veining in regal geranium flowers, this kind of patterning is minimal in the ivies. The species show the greatest amount of darker veins in the upper petals. In most modern cultivars patterning is seen as darker veins and markings on the upper two petals. However, a more uniform pattern of veins may be seen in the cultivar ‘Desrumeaux’.

A few cultivars like ‘Fringed Rouletta’ and ‘Pink Carnation’ have petals with a fine serration along the outer edge of the petals giving a finely fringed appearance, not unlike that seen in carnation flowers.

The leaves of today’s cultivars may be peltate or not, smooth (glabrous) or hairy, scented or scentless, with a dark central zone/spot or not. The old variety ‘L’Elegante’ has a pleasantly scented leaf. Many books state that the scent of ivy geranium leaves is similar to true ivy leaves. I don’t find this to be true. While the margin (edge) of the leaves of P. peltatum is entire (without teeth) modern cultivars (‘Arctic Frost’, ‘Lila Cascade’, ‘Tutti Frutti’) show varying numbers of lobes and teeth on the leaves. This probably indicates a genetic influence from other species in the plant’s ancestry. Leaves in modern cultivars can be variegated too. This may be a simple border of white or ivory around the leaf’s entire blade. Sometimes the white border is of variable width. Some cultivars show a further mottling or marbling of lighter color in the green leaf blade. Plants with a white leaf margin may show varying amounts of leaf cupping - probably related to differential growth rates of green and white leaf tissue. In ‘L’Elegante’ a fine pink line may develop on the edge of the leaf. This is more pronounced on plants under stress.

A few cultivars have a lighter center to the green leaf producing the butterfly pattern familiar in some fancy leafed zonal geraniums. The Whitewood series of ivies has a butterfly leaf. ‘Lilac Whitewood’ is now marketed as ‘Lila Compacta’. A most unusual leaf variegation is found in the cultivars ‘Crocodile’ and ‘White Mesh’. In these plants the tissue above the veins of the leaves lacks chlorophyll (the green pigment of plants) so a reticulate pattern develops. This patterning has  been found to be the result of another viral infection (fairly benign) and it can also be passed to other plants by grafting a piece of stem from an infected, variegated plant to a green, uninfected plant. These patterns were first found on plants growing in Australia. As mentioned before, “new” cultivars are developed by infecting existing cultivars with the virus.

Over the years P. peltatum was crossed with the zonal geraniums so that some of the ivy geraniums we see today show some influences from their zonal ancestry, particularly in the leaf shape, leaf lobing and flower color. Hybridizers continue to cross ivy and zonal geranium to produce the ivy-zonal hybrids. The local ‘Santa Maria Centennial’ is such a cultivar and was produced by Jim Zemcik. Ball Flora- Plant has a whole series of ivy-zonal hybrids which they market as the Galleria series and includes the varieties ‘Ruby Red’, ‘Sunrise’, ‘Bright Violet’, ‘Pink Punch’, ‘SnowFire’ and ‘FrostFire’. Other ivy-zonal hybrids include ‘Rococo’ and ‘Queen of Hearts’ which look more like zonal geraniums than ivy geraniums. The Deacon series of geraniums were the result of crosses between miniature zonals and ivy geraniums but these too look more like zonal geraniums than ivies. Hybridization now also includes crosses between P. peltatum and P. acetosum and P. tongaense. Crosses with the last species have contributed to the Caliente series of Pelargoniums.

I hope this review will give you new appreciation for the great variation that exists within the ivy geraniums but which we rarely see in the market place today. Let’s help keep these wonderful plants alive.

                                                                                                                       September 2009

                         

© 2010, Central Coast Geranium Society (CCGS )