Identifying western Australian summer weeds manual

Published: 1 Jan 2019

The suite of summer weeds present in the Western Australian grainbelt comprises many different species. This makes management decisions difficult and heavily reliant on correct species identification. This booklet aims to help in the identification of the common weeds found in the Western Australian grainbelt. Several weeds present in summer, such as common sowthistle, are able to germinate and reproduce throughout the year; the most common of these have been included along with weeds present only in summer.

Starting point for identification

The starting point to narrow down and identify the majority of weeds (flowering plants) is to figure out whether they are grasses or grass-like (monocotyledons) or broadleaf (dicotyledons).

Grasses and grass-like plants can be identified by the following characteristics:

  • they have a single seed leaf (cotyledon)
  • their leaves lack a leaf stalk; each leaf consists of an upper strap-like blade and a sheathing base that encloses the stem
  • the ligule (where the leaf blade joins the leaf sheath on the upper leaf surface) is either membranous or hairy
  • their leaf veins are parallel with no single main vein
  • their roots are fibrous
  • the plants have no woody parts (herbaceous).

The major monocotyledon families are the Poaceae (grasses), Liliaceae (lilies), Cyperaceae (sedges), Orchidaceae (orchids), Iridaceae (irises) and Alliaceae (onions).

Broadleaf plants can be identified by the following characteristics:

  • they have two cotyledons
  • their shoot system consists of –
    • a main axis (stem)
    • leaves attached to the stem at nodes
  • each leaf consists of a blade (lamina) and a leaf stalk (petiole)
  • leaves have a strongly developed main vein with lateral veins (reticulate pattern)
  • buds form in leaf axils and at the end of stem
  • the root system consists of a primary (tap) root with lateral roots.

This publication groups weeds into grasses or broadleaf (no grass-like weed species are included). Within these two broad groups, the weeds are grouped by plant family, then genus and species. Their common names are given to ensure we are all discussing the same plant.

Hard copies of this report can be obtained from:

GRDC Western Region Office
Suite 5, 2a
Brodie Hall Drive
Ph: 08 9230 4600; email:

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Region: West

ISBN: 978-1-921779-7409 (print)

ISBN: 978-1-921779-73-2 (Online)

GRDC Project Code: ARN1811-001WSX,