This is a striking feature plant with upright cylindrical leaves without a leaf blade, growing from 1 to 2 m in height and producing large orange or yellow flowers borne on long, cylindrical scapes from May to October. Strelitzia juncea is one of five Strelitzia species in southern Africa, namely S. alba, S. nicolai, S. reginae and S. caudata.
A perennial herb 1–2 m high, producing thick fleshy roots and upright cylindrical leaves without a leaf blade. S. juncea does not multiply by suckering from the base of the stem, but subdivision takes place between the middle leaves of each fan. The species is slow growing and takes 3–4 years to flower. Grown under ideal conditions S. juncea is floriferous and long-lived. Although the leaves are very different, flowers resemble those of the more commonly cultivated S. reginae. The inflorescence consists of a boat-shaped spathe bearing five flowers on average. The flower sphathe is held below the level of the highest leaf tips as compared to S. reginae where it is held above the leaves.
||Strelitzia juncea flower sphathe
Distribution and Habitat
S. juncea occurs naturally near Uitenhage, Patensie and just north of Port Elizabeth in the Eastern Cape. These populations of S. juncea grow amongst drought-resistant shrubs belonging to genera such as Euphorbia, Cotyledon, and Pelargonium, as well as Encephalartos horridus, which indicates that S. juncea is able to survive on very little water. Provided it is grown in a well-drained soil, S. juncea adapts well to a high rainfall but requires full sun to flower well.
||Strelitzia juncea growing amongst Euphorbia
Derivation of name and historical aspects
Strelitzia reginae was introduced in England in 1733 and was named after Queen Sophia Charlotte, the wife of George the 3rd of England. She was a princess of Mecklenburg-Strelitz, hence the genus name Strelitzia. The specific name juncea is derived from the Latin, juncus, meaning rush, a reference to its rush-like appearance.
In the past S. juncea was regarded as a variety of S. parvifolia or as a variety of S. reginae until evidence was produced in 1974 by Dr Van de Venter (Dyer 1975) to confirm the specific status of S. juncea. Intermediate forms exist between S. reginae and S. juncea. After extensive studies Dr Van de Venter came to the conclusion that there are genetic differences between these two species and the intermediate forms could be hybrids between the two species.
In its natural habitat, S. juncea is pollinated mainly by sunbirds and sugarbirds. In areas where these pollinators do not exist, it is necessary to hand-pollinate the flowers, always cross-pollinating to ensure a good seed set. In nature the seed is dispersed by birds. This species can withstand light frost. It has a limited distribution, and known populations produce very little seed, because of unpollinated flowers. Pollinators are rarely seen in habitat. According to Raimondo (et al. 2009) its threat status is Vulnerable. This is due to quarrying, illegal collecting for the horticultural trade and invasive alien plants.
Uses and cultural aspects
As a garden subject S. juncea is an ideal accent plant or planted to form a bold group which requires little attention. The flowers are also ideal for cutflowers.
Growing Strelitzia juncea
A well-drained soil is essential for the successful cultivation of this species, full sun for maximum flowering and applications every winter (May/June) of a generous layer of compost as mulch, which is a form of feeding.
In mid summer (November/December) a mixture that has 1 part superphosphates, 2 parts 3.1.5, and 1 part bone meal can be scattered above the root area and watered. This winter and summer feeding cycle, will help a plant grow faster, and to flower earlier and more prolifically. An ideal potting medium is 2 parts loam, 2 parts sand, 3 parts bark, 3 parts compost, ½ part of bone meal and 1part bounce back.
Propagation is by means of seed and division of the fans which will take a year to re-establish. Best results from seed can be obtained by sowing fresh seed in spring. Before sowing, remove the bright orange tuft of hairs ('aril') attached to the seed. The seed can be soaked in sulphuric acid for five minutes and then washed thoroughly under running tap water for a few minutes. The scarified seeds are then soaked in a solution of ethephon (growth regulator) at a concentration of 2000 ppm active constituent. This entails making up 6 ml ethephon (39.5% active ingredient) to a litre of water. Gibberellic acid (GA3) also has similar results as ethephon at the concentration of 800
mg/dm³. One of the two growth regulators can be used to soak the seed for 48 hours, then remove from the solution and sow at a depth of 1½ times the size of the seed. A constant temperature of 25 ºC is most suitable for germination. Squirrels, mice and birds are a problem and the seed needs to be protected on the plant from squirrels and, once sown, birds and mice need to be kept out by protecting the seed trays with netting.
Propagation by dividing clumps ensures that clones of the same plants will be obtained. This is best done in autumn or winter. The fleshy roots are difficult to dig up and take time. Dividing into big clumps (60 cm plus in diameter) ensures that plants will recover quicker. It will take about two to three years before they are back to their flowering peak. Transplanting should be complemented by a summer feed, as mentioned above; this can be mixed in the planting hole with a dam above for the first year to catch water.
References and further reading
- Batten, A. & Bokelmann, H. 1966. Wild flowers of the Eastern Cape Province. Books of Africa, Cape Town.
- Dyer, R.A. 1975. The status of Strelitzia juncea (Strelitziaceae). Bothalia 11: 519, 520.
- Dyer, R.A. 1980. Strelitzia juncea. The Flowering Plants of Africa 46: t. 1804.
- Manning, J. 2001. Eastern Cape. South African Wild Flower Guide 11. Botanical Society of South Africa & National Botanical Institute. Cape Town.
- Raimondo, D., Von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. & Manyama, P.A. (eds). 2009. Red List of South African plants. Strelitzia 25. South African National Biodiversity Institute, Pretoria.
- Pogroszewska E . 2006. The effect of scarification, gibberellic acid and ethephon on seeds germination and the growth of Strelitzia reginae banks seedlings. Zeszyty Problemowe Postepow Nauk Rolniczych vol : number : 510, pages : 479- 489
Kirstenbosch National Botanical Garden
(Updated by Phakamani Xaba, August 2011)