Invader plants that were ornamentals

The ARC Plant Protection Research Institute recently highlighted three more alien invasive plants that smallholders should be on the lookout for . Any smallholders who frequent lakes or dams in Gauteng are likely to have seen the Yellow Water Iris , or Yellow Flag ( Iris Pseudacorus). These plants are rooted , and develop rhizomes that form large clumps of underwater and above-water mats . The lanceolate , erect leaves are green or blue-green , up to 1 mlongand3cmwide . The flowers are typically iris-like - yellow , large and showy . The yellow water iris has become invasive along riverbanks , on drainage lines , and on the edges of dams , where it has the potential to form impenetrable thickets much like water hyacinth . The plant spreads rapidly from seeds and rhizomes that are carried along by water , and which readily take root in the shallow edges of water bodies . Furthermore , the underwater rhizomes are capable of producing many more cloned plants per year . The rhizomes are tolerant of drought and can survive for months without water , but rapidly regenerate in wet

Continued on page 33

Yellow Water Iris

31 www . sasmallholder . co . za