Piper aduncum L. (Matico tree) is native to the West Indies and mainland tropical America from Mexico to northern Argentina and has a number of uses, including traditional medicines and agroforestry. It has been a successful invader in many areas. Despite the successful spread of P. aduncum, very little is known about its basic biology. As this species most often dominates roadsides and forest margins, and these habitats frequently experience extreme changes in temperature and water availability, it is important to understand how the seeds adapt to these stresses.

Dr. WEN Bin and his students of Xishuangbanna Tropical Botanical Garden (XTBG) investigated the responses of P. aduncum seed germination to temperature and water potential. They aimed to improve the understanding of its advantages and limitations as an invasive species. They designed two experiments to assess the effects of relative humidity and high temperature on quiescent seeds. They then carried out two experiments to investigate the temperature and water requirements for seed germination. They also performed two experiments to assay the response of seed germination to high temperatures. Lastly, they conducted an experiment to determine the stages of seed germination that are sensitive to high temperature and water stress.

  It was found that P. aduncum seeds exhibited only intermediate tolerance and did not germinate at temperatures above 35°C or water potentials below −0.6 MPa. However, this species is well adapted to local conditions of Xishuangbanna. 

   In Xishuangbanna, P. aduncum occurs only along roadsides and in thickets, although this species can grow in open sites and form monospecific stands in Malaysia and Kalimantan, while Chromolaena odorata can grow and form tickets in open fields in Xishuangbanna because it has a markedly higher tolerance to abiotic stress than P. aduncum. Thus, the intermediate tolerance to high temperature and water stress of P. aduncum, in combination with local environmental conditions of Xishuangbanna, made P. aduncum an intermediate invader in this area.

    P. aduncum has only limited success in invasion to Xishuangbanna, restricted to relatively wetter and cooler habitats, such as roadsides and forest ridges. The researchers suggest that P. aduncum will remain as an intermediate invader in this area, and not become a problem as serious as Chromolaena odorata.

The study entitled “Seed germination of the invasive species Piper aduncum as influenced by high temperature and water stress” has been published in Weed Research.