poor man’s Rhododendron
I. oliveri, I. magnifica, I. uguenensis
Native to East Africa
Glabrous (hairless) perennial (life span extends over more than 1 season) subshrub to 1.5 m high, with big pale pink or white flowers. Fruits “explosive”.
Grows on exposed rocky hills on one locality in SW Western Australia. It has also been recorded as naturalized in Merimbula on the NSW far south coast, where it has persisted for at least since 2001 in a moist, shaded, heavily weed infested gully close to a coastal lake, a very different habitat from that described in Western Australia. In Merimbula it is confined to only the moistest soils in the lower part of this gully. It is occasionally grown as an ornamental in Australia. The plant has naturalised in Hawaii and New Zealand.
Stems and Leaves:
The stems are thick and succulent, simple or only moderately branched, glabrous (hairless), becoming slightly woody below. The bright green leaves are in dense whorls of 6-12, rather congested towards the stem top, glabrous (without hairs or scales), sessile or subsessile, oblanceolate, rarely oblong, 5-18 cm long and 2-5 cm wide, with 7-10 pairs of lateral veins. Leaf margins shallowly serrate or serrulate (finely toothed), leaf colour is similar on upper and lower surface.
Flowers and Fruit:
The flowers appear singly or in pairs at the leaf-stem junction at the top of the plant. They could be pale pink or white, sometimes with darker marks, 5 petalled, about 5 cm in diameter. Upper petal crested, lateral petals fused towards base. Flower stalks 2.5-6 cm long. Lateral sepals 2, small, green, 6-8 mm long. Lower sepal shallow, abruptly constricted into 7-8 cm long narrow spur. The flowers appear throughout the year. The fruit is a smooth greenish capsule, c. 24 mm long and 8 mm wide, swollen in the middle. Ripe fruits explode with even slight pressure.
It can be distinguished from busy Lizzie I. walleriana in that Impatiens sodenii is a taller plant, with bigger pale pink or white flowers, stems simple or only moderately branched and sessile leaves in dense whorls 6-12 rather congested towards stem top. Whereas in I. walleriana plant is less than 1 m high, has flowers in darker shades of pink, salmon-pink or red, sometimes also white, its stems are branched and leaves are on long petioles, spirally arranged.
I. niamniamensis recently found occasionally naturalising in New Zealand has striking red-yellow-green flowers and saccate (pouch-like) lower sepal with upright spur.
Policeman’s helmet I. glandulifera, Kashmir balsam I. balfourii and I. balsamina are annual plants with a saccate (pouch-like) lower sepal.
Sources & References
Grey-Wilson C. (1980) ‘Impatiens of Africa.’ A. A. Balkema, Rotterdam
Heenan P.B., de Lange P.J., Cameron E.K., Ogle C.C. & Champion P.D. 2004. Checklist of dicotyledons, gymnosperms, and pteridophytes naturalised or casual in New Zealand: additional records 2001-2003. New Zealand J. Bot. 42: 797-814.
Sykes W.R. (1982) Checklist of dicotyledons naturalised in New Zealand 15. New Zealand J. Bot. 20: 333-341
Wester L. (1992) Origin and distribution of adventive flowering plants in Hawai‘i. In: Stone, Charles P.; Smith, Clifford W. and Tunison, J. Timothy. Alien plant invasions in native ecosystems of Hawaii: Management and Research. University of Hawaii, Cooperative National Park Research Studies Unit, Honolulu. University of Hawaii Press.
Prepared by Wojciech Adamowski & Jackie Miles, February 2006
FloraBase the Western Australia flora http://florabase.calm.wa.gov.au/