Gramineae (Poaceae)


Echinochloa crus-galli
Michigan St Univ CSS 402/056


Gramineae fossil, JWE, CA
UofAz Palynology


Agropyron trachycaulum
UofAz Palynology

Plant:
Narrow-leaved plants with basal meristems. Flowers generally in compact heads, fruits caryopses. Cosmopolitan in tropical to alpine habitats.

Pollen light micrograph:
Pollen spheroidal to suboblate, with a single circular pore (rarely more, see image above) surrounded by a distinct thickening of the outer and inner wall (annulus). Pore covered by operculum comprised of both layers of the wall. Grass grains larger than 45 µm and witn robust annuli may be cultivated species (Cerealea). Grains larger than 65 µm may be corn (Zea).

Pollen scanning electron micrograph (SEM)
Surface gently roughened (scabrate).

Production and Dispersal:
Moderate production and dispersal. Grasses are wind pollinated, so grass pollen is common, however the percentages are seldom greater than 25%.

Preservation:
Preservation moderate to good, often present in poorly-preserved samples.

Fossil Occurrence:
Present in the late Cretaceous (?) but rising to dominance from the Oligocene (20 My) onward.

References:
  • Alopecurus antarcticus Markgraf 1978, #45
  • Bromus mango Heusser 1971, pl 11, fig 111
  • Cenchrus pauciflorus Markgraf 1978, #47
  • Dactylis glomerata Markgraf 1978, #50
  • Danthonia werdermannii Markgraf 1978, #51
  • Distichlis scoparia Markgraf 1978, #52
  • Festuca gracillima Markgraf 1978, #53
  • Festuca pallescens Markgraf 1978, #54
  • Hierchloe antarctica Markgraf 1978, #55
  • Hierochloe gunckelii Heusser 1971, pl 11, fig 118
  • Hordeum halophilum Markgraf 1978, #56
  • Koeleria grisebachii Markgraf 1978, #57
  • Leptochloa uninervia Heusser 1971, pl 11, fig 121
  • Melica violacea Heusser 1971, pl 11, fig 112
  • Muhlenbergia asperifolia Heusser 1971, pl 11, fig 122
  • Munroa mendocina Markgraf 1978, #58
  • Phleum alpinum Markgraf 1978, #59
  • Piptochaetium bicolor Heusser 1971, pl 11, fig 110
  • Poa chilensis Markgraf 1978, #60
  • Stipa brachychaeta Heusser 1971, pl 11, fig 120
  • Stipa humilis Markgraf 1978, #61
  • Tripsacum dactyloides Irwin 1965, Pl 3, fig A


  • Heusser, C.J. 1971.
    Pollen and spores of Chile. University of Arizona Press, Tucson, 167 p.

    Markgraf, V. and H. L. D'Antoni. 1978.
    Pollen flora of Argentina. University of Arizona Press, 208 p.
Links

Owen K. Davis 01/00