Digitaria

Digitaria Sanguinalis

Pictured above: Digitaria sanguinalis

This genus has decumbent-spreading stems with wide flat leaf blades. The inflorescence is a panicle in which the spike-like branches are arranged in digitate fashion. The spikelets are arranged in 2 rows on an angled or winged rachis. Each spikelet has 2 florets, only one of which is fertile. The first glumes are either very minute or absent.

There are 2 species in MN; none are native.

Common species:

Digitaria ischaemum (di git tear' ee ya ish key' mum)

  • Synonyms: None
  • Common names: smooth crabgrass
  • Origin and habitat: Introduced from Europe; disturbed areas and lawns
  • Identifying characters: Leaves have keeled sheaths, are smooth or occasionally sparsely hairy at the collar, and the ligules are 0.5-2 mm long. Spikelets are often purplish-black at maturity.
  • Comments: Apparently a bit more tolerant of abuse than the following species, smooth crabgrass is more often found in pavement cracks. See the discussion with the following species for more information.

Digitaria sanguinalis (di git tear' ee ya sang guin al' lis)

  • Synonyms: None
  • Common names: hairy crabgrass, northern crabgrass, pigeon grass
  • Origin and habitat: Introduced from Europe; disturbed areas and lawns
  • Identifying characters: Very similar to smooth crabgrass (D. ischaemum), hairy crabgrass differs in having leaves usually pubescent, with bulbous-based hairs, and spikelets that become brownish rather than blackish.
  • Comments: Both smooth and hairy crabgrass are extremely difficult to eradicate. They germinate after other lawn grasses and can grow rapidly, often out-competing under hot and dry conditions. This is especially true on open soils when you are trying to reseed other lawn grasses. If allowed to take over, the stems will become decumbent and flatten along the ground, interfering with other grasses. In ancient times, the crabgrasses were cultivated as a cereal crop in central Europe. It is hard to believe but crabgrass was (perhaps still is) grown in Europe as an ornamental!

Maps

Digitaria ischaemum mapdigitaria sanguinalis map   

Additional species in Minnesota:
None

Copyright 2002, A.F. Cholewa, J.F. Bell Museum of Natural History, University of Minnesota / No portion of this guide may be duplicated without written permission of author.