Mexican Bamboo
(Polygonum cuspidatum)

B. Rosie Lerner, Extension Consumer Horticulturist, Department of Horticulture & Landscape Architecture, Purdue University

Although Mexican bamboo is not a true bamboo, perhaps it gets that name from the towering stems that can reach up to 8 feet!  Or maybe it takes its name from the invasive, spreading habit, sending rhizomes far and wide and sending up new shoots even in this asphalt parking lot!!

It’s easy to identify this plant, in addition to the hollow zig-zag stems, the alternate leaves are up to 5 inches wide, ovate to triangular in outline, and tapering to an abrupt point. Also known as Japanese knotweed, this plant is a member of the buckwheat family (Polygonaceae) and has the family’s characteristic ochrea; a membraneous sheath where the leaves join the stem. The small greenish-white flowers are borne in axillary clusters.

Mexican bamboo is sometimes planted as an ornamental, but we get many more inquiries on how to get rid of it!  Digging it out may help slow it down, but any piece of rhizome that remains behind will regrow. A non-selective herbicide such as glyphosate can be spot-applied to the foliage as it re-sprouts, but will often take multiple applications. Always read and follow label directions before you apply any pesticide.

Click image to enlarge