Beautés fatales: Acanthaceae species as invasive alien plants on tropical Indo‐Pacific Islands

• DOI: 10.1111/j.1366-9516.2004.00094.x
• Publication Date: 2004-09-06T15:57:55Z
• Authors: Jean‐Yves Meyer; Christophe Lavergne
• Keywords: Ruderal species; Understory; Acanthaceae

ABSTRACT Most, if not all, alien plant species of the family Acanthaceae (acanths) found in tropical islands were intentionally introduced as garden ornamentals, because their showy coloured flowers, bracts or leaves. Some have ‘escaped’ gardens and naturalized human‐disturbed areas weeds, adventives, ruderal species. A few successfully invaded secondary relatively undisturbed native wet forests. This paper reviews acanths islands, focuses on currently invasive potentially study is based recent (1994–2004) botanical surveys field observations conducted several oceanic Pacific Indian Oceans, bibliographical searches other countries. total 52 acanth are Indo‐Pacific islands; 26 them to Asia, 18 America, only 8 Africa. The number selected continental varied from 7 25 rate (number species/number species) 27% 62%. We recorded eight major species: erect herbs shrubs Justicia carnea , Odontonema strictum Phlogacanthus turgidus Sanchezia speciosa Strobilanthes hamiltonianus form dense monospecific thickets understorey forests; woody vine Thunbergia grandiflora smothers trees; creeping herb Hemigraphis alternata forms carpets that totally cover ground; Ruellia brevifolia colonizes closed‐canopy forest. also discuss incipient which subspontaneous sparingly naturalized, but yet considered invasive. Most sterile, lack fruit production being explained by absence pollinators and/or particular floral structure reproduction modes. They reproduce vegetatively stem fragmentation root suckers, range expansion thus slow. Their success may be attributed long (50–100 years) residence times, long‐distance dispersal humans. Many newly ornamentals produce seeds, constituting greater threats. recognized an ‘aggressive’ (e.g. compared Fabaceae, Melastomataceae, Poaceae, Rosaceae). It is, however, one most popular ornamental families Tropics, should receive more attention increasing current islands.