Glyceria grandis

Species category

Weed

Common name

American mannagrass

Diagnostic characters

Planting unit

FloretFloret:
A small flower in a clustered inflorescence (e.g., sunflower, grasses). In grasses, a floret consists of the lemma, palea, stamens, and pistil.

Shape

ObovateObovate:
Inverted egg shaped with apical end the broadest.

Size

  • Length 2 mm 
  • Width 0.75 mm 
  • Thickness 0.5 mm 

Color

Light brown with purple tinge

Texture

Lines on lemmaLemma:
One of two bracts of the grass floret; it is located on the side nearest the embryo and opposite the rachilla.
finely tuberculateTuberculate:
Having small pimple-like protuberances.
; paleaPalea:
One of the thin bracts of grass floret enclosing the fruit (caryopsis) that is located on the side opposite the embryo.
smooth and hairy margins.

Lemma

5-6 longitudinal lines; small, thin hump above callusCallus:
The hard base of grass florets or spikelets, just above the point of disarticulation.
.

Palea

Same length as lemmaLemma:
One of two bracts of the grass floret; it is located on the side nearest the embryo and opposite the rachilla.
and protruding outward

Other structures

Thin callusCallus:
The hard base of grass florets or spikelets, just above the point of disarticulation.
below hump; rachillaRachilla:
The axis of a spikelet.
widest at base and apexApical:
The distal end of the fruit or seed away from the point of attachment or attachment scar.
.

Identification notes

CaryopsisCaryopsis:
The single-seeded fruit or grain of the grass family (Poaceae); the fruit wall (pericarp) is united with the seed coat (testa).
is very dark and obovoid. PaleaPalea:
One of the thin bracts of grass floret enclosing the fruit (caryopsis) that is located on the side opposite the embryo.
is slightly convex at its base to accommodate the rounded caryopsisCaryopsis:
The single-seeded fruit or grain of the grass family (Poaceae); the fruit wall (pericarp) is united with the seed coat (testa).
.

Noxious weed seed categories

Not listed

AOSA examination list

Included

Nomenclature

Family

Poaceae

Valid name

Glyceria grandis S. Watson

 Glyceria grandis.  Florets with a dark and obovoid caryopsis and a slightly convex palea.
Glyceria grandis. Florets with a dark and obovoid caryopsis and a slightly convex palea.