Grass weed morphology and ID is often much harder than broadleaf weed ID. This is
because superficially all grasses look the same. Get close, and you will notice many
features that will guide your ID.
Leaf morphology
This is a generic grass leaf in cross-section. Notice
the prominent midrib.
Ligule & Collar region
The different parts of the collar region, where the leaf blade joins the culm (stem), can
be a very revealing area for grass ID.
Below (clockwise): Upper right: blade; middle right: collar region; lower right: sheath;
lower left: auricles; middle left: ligule
Below (Clockwise): lower right, sheath; lower left (2 arrows), auricles; collar; mid-left, ligule; leaf blade; upper left, midrib; upper right, leaf margin; mid-right, collar margin
Ligule types:
Membranous ligule 
No ligule 
Hairy ligule 
Sheath:
No auricles: 
Auricles: 
Sheath split with overlapping margins: 
Sheath united: 
Stems:
Round 
Oblong 
Flat 
Triangular (diagnostic for sedges) 
Inflorescence, seedhead:
Seed:
(optional information; not required)
From top: awn; lemmas; glumes
From top: palea; lemma; rachilla
From top: stamen; stigma; ovary; lodicule
Top view: grass floral schematic diagram
From top: hilum; endosperm; coleoptile; plumule;
mesocotyl; epiblast; scutellum; scutellum cleft; coleorhiza
