Identifying invasive cacti by the size of their seeds

22 August 2016 | By Ana Novoa

C·I·B researchers Ana Novoa (C·I·B Post-doc) and Dave Richardson (C·I·B Director) together with colleagues from the University of Vigo, in Spain, identified that the seeds of cactus plants can be used as an effective way of detecting invasive cacti.

Hundreds of cactus plants are introduced to South Africa as seeds for ornamental purposes, but unfortunately many of them become serious invaders across the landscape. Although the introduction of invasive and potentially invasive cacti in South Africa should be prevented, identifying cactus species by their seeds is a difficult task for the untrained eye.

In their study, which was published in the South African Journal of Botany, the authors searched for websites selling cactus seeds and found that seeds of 266 cactus species are being traded internationally. This included 24 cactus species known to be invasive in South Africa.

The authors bought seeds of each species and found that invasive and potentially invasive species had larger and heavier seeds than non-invasive species.

Management strategies to minimize negative impacts of invasive species include the prevention of new introductions, early detection and eradication, and the control of widespread invaders. Prevention is the most cost efficient of these strategies.

“Practical measures for identifying and intercepting invasive cacti before they are introduced are crucial. Seed size and mass are useful features for detecting the introduction of potentially invasive cacti,” explains Ana Novoa, “they are effective and really easy to measure”.

Read the paper in the South African Journal of Biology

Novoa, J Rodríguez, A López-Nogueira, DM Richardson and L González (2016) Seed characteristics in Cactaceae: Useful diagnostic features for screening species for invasiveness? South African Journal of Botany. doi: 10.1016/j.sajb.2016.01.003

For more information, contact Ana Novoa at novoa.perez.ana@gmail.com
Website: http://novoaperezana.wix.com/novoa

For more articles on cacti as invasive species

1. Novoa, S Kumschick, DM Richardson and JRU Wilson. (2016) Native range size and growth form in Cactaceae predicts invasiveness and impact. Neobiota (in Press)
2. Novoa, H Kaplan, JRU Wilson, and DM Richardson (2016) Resolving a prickly situation: Involving stakeholders in invasive cactus management in South Africa. Environmental Management. doi: 10.1007/s00267-015-0645-3
3. Novoa and R. Shackleton (2015) Stakeholder involvement: Making strategies workable. Quest 11(2): 54-56
4. Novoa , H. Kaplan, S. Kumschick, J.R.U. Wilson, and D.M. Richardson (2015) Soft touch or heavy hand? Legislative approaches for preventing invasions: Insights from Cacti in South Africa. Invasive Plant Science and Management 8:307–316
5. Novoa, J.J. Le Roux, M.P. Robertson, J.R.U. Wilson, and D.M. Richardson (2015) Introduced and invasive cactus species–a global review. AoB Plants 10.1093/aobpla/plu078
6. Laguna, V.I. Deltoro, P.P. Ferrer, A. Novoa and D. Guillot (2013) About the binomen Cylindropuntia rosea (Cactaceae) and its invasive individuals recorded in the Valencian Community (Spain). Bouteloua 16: 40-51