Plant Highlights
Plant Highlights By Date Plant Highlights Alphabetically
Plant Highlight: Pelargonium echinatum
by Brian Kemble
Family placement and area of occurrence
Pelargonium is a large genus in the Geraniaceae, or Geranium Family, with the majority of the species found in southern Africa.* While the leaves of the various species are seldom more than slightly succulent, quite a few have succulent stems. One of these, Pelargonium echinatum, is spiny as well, with the spines being stipular spines. Stipules are projections on either side of the base of a leaf, and they may just be inconspicuous bumps in some plants, but in other cases they are modified to serve a protective function (hardening into spines), or modified into tendrils to support climbing plants. It is interesting to note that spiny plants are also found in another genus in the Geraniaceae, Monsonia, but here the spines are petiolar rather than stipular (that is, they are hardened leaf-stalks instead of stipules). P. echinatum comes from dry parts of western South Africa, from the Richtersveld (in the country’s northwest corner) southward to Clanwilliam.
About the plant
Plants of Pelargonium echinatum may have erect-growing branches that produce a plant that is taller than it is wide, but often the branches extend out laterally to produce a sprawling shrub. Upright-growing plants may attain a height of as much as 2 feet (60 cm). The stems are grey or tan in color and about a quarter-inch in diameter (6 mm). The stipules occur on the stems to either side of the leaf attachment point, and they are about .16 to .2 inch long (4 to 5 mm). Sometimes they stick straight outward, but in other plants they hook downward. Plants are summer-deciduous, so the spiny stems are on full display at that time of year. The newly emerging leaves in autumn are initially very crinkly and hairy. The hairiness diminishes as the leaf expands to its full size, but the margins remain crenulate and are frequently somewhat undulating as well. The overall shape of the leaf is more or less ovate, but often with an indented base (at the attachment point) that results in a rounded heart shape. There are 3 to 5 shallow lobes, but these may not be obvious due to the undulations and crinkled margins. The upper leaf surface is deep green to dark gray-green, while the underside is notably paler. The leaf blade can vary considerably in size, but a large leaf may be up to 3¾ inches long (9.5 cm), with a pedicel (leaf stalk) that may be even longer. The branches that produce the flower clusters are longer than the other branches, with smaller leaves, and they may fork to yield multiple inflorescnces.
About the flowers and fruits
P. echinatum has a long flowering period in winter and spring, with multiple long peduncles, each bearing a cluster of 3 to 9 flowers that radiate from the tip. The flowers have a diameter of about an inch (2.5 cm), held atop a pedicel (the stalk of the individual flower) about 1.2 to 1.6 inches long (3 – 4 cm). As is usual in the genus, the flowers are bilaterally symmetrical, not radially symmetrical. There are 2 broader upper petals, somewhat overlapping, and 3 spreading narrower lower petals. The upper pair have dark red or purple blotches and streaks, and occasionally there may be less conspicuous markings on the lower petals as well. The flower color ranges from white to pink to purple, and often the flowers darken as they age. In many plants the flowers are white when they first open, then darkening to pink or purplish-pink as the days go by. Flowers of varying ages present on the same plant provide a multi-hued display that make this species a garden stand-out. At the center of the flower is the pistil, topped by 5 recurved stigma-lobes. Surrounding the pistil are the 10 stamens, but some of the stamens are sterile, so the orange pollen is usually present on only 6 or 7 of them. The capsule of P. echinatum, called a schizocarp, is long, narrow and beak-like. At maturity it splits into 5 one-seeded mericarps, each with a curling awn that helps the seeds work their way into the soil when they fall.
Plants in cultivation
Coming as it does from the winter-rainfall area of western South Africa, Pelargonium echinatum does well in areas with dry summers and rain during the winter months. This means it does well in California’s Mediterranean climate, provided it gets plenty of sun and good drainage. When planted in a garden with other plants that need to get watered in summer, it can tolerate occasional water during its resting period, but it comes from areas with low rainfall, and frequent watering should be avoided. It can endure overnight lows down to the mid-20’s F (to -4° C), but not extended freezes. This species can be grown from cuttings, and this is best done in the fall, when the new growth is just emerging after its summer dormancy.
*Note that in the nursery trade, plants in the genus Pelargonium are commonly referred to as “geraniums”. However, Geranium is actually a separate genus in the same family.
Click here to find out more about what’s in bloom at the Garden.
