Invasion Biology

Wednesday, January 24, 2007

CITY OF JACARANDA TREES

Jacaranda trees were introduced to South Africa in 1880 for ornamental purposes. After 100 years until now the trees have invaded most parts of South Africa especially Pretoria (Tswane). The tree that is most often seen is the Blue Jacaranda (Jacaranda mimosifolia) Pretoria in now called the Jacaranda City and most people thinks that Jacaranda trees are native at Pretoria while they were imported from Argentina. The tree is native to the tropical and subtropical regions of Central and South America, the Caribbean and Mexico. There are more than 50 000 trees in South Africa now [1]. The trees are found in enormous numbers since they are planted as street trees, in parks and gardens. During flowering time the city appears to be purple/blue in colour because of the jacaranda flowers. There is also a myth that says “if a flower from a Jacaranda tree drops on your head, you will pass all your exams” [2].

Jacaranda has 49 species of flowering plants which belongs to the family Bignoniaceae. The Blue Jacaranda is a tree which is 5 to 15 metres tall. The bark is greyish-brown in colour and rough. The bark is only smooth when the tree is still young. The twigs are thin and turn to be ziz-zag in shape and they are reddish-brown in colour. The flowers of the Blue Jacaranda are 5 centimetres long, grouped in 30 centimetre panicles. It flowers in spring and early summer and the flowers last for two months. The seeds are found in the woody pods and they are 5 centimetres in diameter. The woody pods contain numerous winged seeds inside. The leaves are 45 centimetres long and compound. The leaflets are up to 1 centimetre long [3].

The Blue Jacaranda likes to grow in a place where there is no risk of frost and they can tolerate the temperature of -7ºC. The Blue jacaranda is regarded as a naturalised species in Miami-Dade country, Florida and Hawaii while in South Africa, Queensland and Australia is referred as invasive. The Blue Jacaranda prevent grow of native species by consuming a lot of water [3].

A company in South Africa has won a World Bank award for manufacturing eco-friendly coffins using wood from invasive non-native plants [1]. This is one of the reasons why the jacaranda tree was planted in South Africa. So some people may want to plant more plants so that they can make profit from the tree or maybe this can reduce the number of trees.

The government listed the jacaranda as an invasive species, which means the trees which already exist must be kept but no more planting of the jacaranda tree. So people did not agree with the government, they wanted to replace the dead trees [1]. The jacaranda trees are beautiful especially during flowering time (spring).

Reference

1. http://news.nationalgeographic.com/news/2005/09/0916_050916_triffidweed_2.html

2. Wikipedia contributors. Jacaranda [Internet]. Wikipedia, The Free Encyclopedia; 2007 Jan 12, 07:06 UTC [cited 2007 Jan 23]. Available from: http://en.wikipedia.org/w/index.php?title=Jacaranda&oldid=100177697.

3. Wikipedia contributors. Blue Jacaranda [Internet]. Wikipedia, The Free Encyclopedia; 2007 Jan 1, 23:10 UTC [cited 2007 Jan 23]. Available from: http://en.wikipedia.org/w/index.php?title=Blue_Jacaranda&oldid=97815550.

Lethabo Mosomane
CSIR
Pretoria
0001
Tel: 27 12 841 2133
Fax: 27 12 842 3676
mail: lmosomane@csir.co.za
http://lmosomane.blogspot.com

4 Comments:

  • Interesting.

    A little bit more about the history of the jacaranda and its spread would've been nice, though. As would a discussion of why it's so successful an invader.

    By Blogger NcK, at January 24, 2007 5:06 PM  

  • Whats the causes of the jacaranda trees or the effects which they cause to the environment?

    By Anonymous Anonymous, at August 07, 2013 2:05 PM  

  • This comment has been removed by the author.

    By Blogger Eric Bolsmann, at June 20, 2016 5:26 PM  

  • The description on the jacaranda trees in Pretoria is factually incorrect and badly presented. There are many excellent references on the tree of Brazilian origin available, of which two sapling were introduced to Pretoria in 1888 by a Mr Tempelman from Pietermaritzburg.
    The writ was badly researched and should never appear on the Net.
    Please list sources and do your homework.
    One source is my booklet, "Jacaranda – Pride of Pretoria", and also "Pretoria: Artists Impressions 1857 – 2001."

    By Blogger Eric Bolsmann, at June 20, 2016 5:33 PM  

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