Agapanthus africanus

(L.) Hoffmanns.

Including Agapanthus africanus subsp.walshii (Leighton.) Zonn. & Duncan comb. Nov.

Family: Agapanthaceae
Common name:
Agapanthus

 

Agapanthus africanus subsp. africanus
Agapanthus africanus subsp. africanus
Agapanthus africanus subsp.walshii
Agapanthus africanus subsp.walshii

Agapanthus are one of South Africa's best known garden plants and are grown in most countries in the world. Their strap-like leaves and striking blue or white flowers make them favourites in plant borders as well as in containers. They are all easy to grow except for A. africanus and A. walshii which a recent publication (Zonneveld & Duncan 2003) has proposed is a subspecies of A. africanus.

Agapanthus africanus was the first Agapanthus species collected in South Africa and was described in 1679 by the name Hyacinthus Africanus tuberosus, flore caeruleo umbellato. Plants were grown in containers in conservatories and flowered in Europe in the late seventeenth century. Sometimes Agapanthus africanus is still referred to as Agapanthus umbellatus and many laypersons as well as nurserymen confuse Agapanthus africanus with Agapanthus praecox, which is a popular, easily grown species. Any Agapanthus referred to as 'africanus' in the nursery trade is almost certainly Agapanthus praecox.

Agapanthus africanus subsp. africanus

Distribution
Agapanthus africanus subsp. africanus is found only in the Western Cape Province, which is a winter rainfall area. The plants grow from the Cape Peninsula to Swellendam, from sea level up to 1000 metres, mainly in mountainous terrain in acidic sandy soil. They often grow between rocks and even in depressions on sheets of sandstone rock. The plants will not tolerate freezing weather for any length of time.

A. africanus  subsp. africanus  flowers well after fire.

Description
The perianth segments of A. africanus subsp. africanus are thick in texture and the flowers are open faced and range in colour from light to mainly deep blue. Rare sightings of white flowered plants have been recorded. Fires stimulate profuse flowering. After a recent fire in the Silver Mine Nature Reserve on the Cape Peninsula a single white flowered plant was noted amongst thousands of blue flowered ones. The plants flower mainly from December to February. The leaves are evergreen and strap like, about 15 mm wide with an average length of 350 mm. The flower stalk is usually under 700 mm tall. This subspecies is quite common and because of the fairly inaccessible terrain its survival is assured.

Agapanthus africanus subsp. walshii (Leighton) Zonn and Duncan comb.nov.

In a recent publication, Agapanthus walshii has been renamed as a subspecies of Agapanthus africanus. The authors, using nuclear DNA content (2C) and pollen vitality and colour are proposing that the ten species recognised by F.M. Leighton in her 1965 Agapanthus revision be reduced to six species and the name change Agapanthus africanus subsp. walshii has been published. This reclassification needs further study into the morphological characteristics of the plants to be fully supported.

Growing in habitat

Distribution.
Housing creeps closer to A.africanus subsp.walshiiThis Agapanthus grows only in the Steenbras area of the Western Cape Province in a fairly restricted area. Although it was originally thought to be rare, it is fairly plentiful within its distribution area most of which falls within a conservation area and its future seems secure. Unfortunately an informal housing settlement has arisen in an unrestricted area where most of a colony of plants has been destroyed or is in danger of disappearing due to human activity. Agapanthus africanus subsp. walshii is found only at an altitude above 600 m and grows in very rocky areas in sandy acid soil.

Description
The flowers are pendulous, often light blue, seldom dark blue and rarely white. The leaves are evergreen, mainly erect and on average 10 mm broad and 200 mm long. The flower stalk is 600 mm tall. It also flowers best after a fire.

Ecology of A.africanus
Pollination is by wind, bees and sunbirds. Baboons and buck sometimes eat the flower heads just as the first flowers begin to open. The seed which is often parasitized is dispersed by the wind. These plants are adapted to survive fire in the fynbos. They resprout from thick, fleshy roots.

Growing Agapanthus africanus

Both subspecies of Agapanthus africanus are difficult to grow. A africanus subspecies africanus is not suitable as a garden plant except in rockeries. They are best grown in containers in a well drained, slightly acid sandy mix and appear happiest if pot bound. They seem to grow best in shallow containers and will flower regularly if fed with a slow release fertiliser.

A. africanus subsp. walshii is by far the most difficult agapanthus to grow. The best medium appears to be a very well-drained, sandy, acid mix with minimal watering in summer. It can only be grown as a container plant and will not survive if planted out. It is unfortunate that it is so hard to grow because it is most attractive when in flower and would make an excellent pot plant.

Both subspecies can be propagated by fresh seed. The seed germinates best if sown in a well-drained seed mix and lightly covered. The seed trays should be placed on heated beds under a mistspray set for about five minutes twice a day. Germination takes place in 4 to 6 weeks and the trays should then be removed to a lightly shaded area. Good results will also be obtained when the trays are placed indoors or outdoors in light shade and watered twice a day, provided the day time temperature is higher than 18° Celsius.

References

  • Leighton, Frances M. 1965. The Genus Agapanthus L'Heritier. Journal of South African Botany, Supplementary Volume No. IV
  • Duncan, G. 2002. Grow Agapanthus. Kirstenbosch Gardening Series, National Botanical Institute, Cape Town.
  • Zonneveld, B.J.M. and Duncan, G.D. 2003. Taxonomic implications of genome size and pollen colour and vitality for species of Agapanthus L'Heritier (Agapanthaceae). Plant Syst. Evol. 241: 115-123 (2003).

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Centre for Home Gardening, Kirstenbosch
May 2004

 

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