Sporobolus

Sporobolus cryptandrus Sprobolus c2

Pictured above: Sporobolus cryptandrus

This genus is characterized by open panicles of 1-flowered spikelets. Spikelets have glumes usually shorter than the lemma, which are 1-nerved and unawned. This is one of the few grasses that does not produce a true caryopsis as the seed coat is not fused to the ovary wall. In both of our species at least, a mucilage in the fruit interacts with the smallest amounts of water (such as a light sprinkling or dew); the fruit then enlarges and bursts explosively sending seed wide and far.

There are 5 species in MN; 5 are native.

Common species:
Sporobolus cryptandrus (spore ah' bow lus cryp tan' drus)

  • Synonyms: None
  • Common names: sand dropseed; Lakota: peji takan
  • Origin and habitat: Native; dry sandy areas and along sandy roadsides
  • Identifying characters: Leaves are somewhat tough with purplish bases and short ligules consisting of a short, dense fringe of hairs; longer silky hairs are at the ligule margins and continue down the sheath margin a short way. The leaf is pubescent on the backside of the collar area as well. The base of the inflorescence is usually partially concealed in the upper-most leaf and flowers in this portion often self-pollinate. Upper branches often are at right angles to the main inflorescence axis. Spikelets are 2-3.3 mm long and often purplish black.
  • Comments: Sand dropseed is a prolific drought tolerant species.

Sporobolus heterolepis (spore ah' bow lus heh tear o lee' pis)

  • Synonyms: None
  • Common names: northern dropseed, prairie dropseed; Ojibway: na ba gashkoons
  • Origin and habitat: Native; dry prairies but often in depressions
  • Identifying characters: Leaves are basal, wiry, arching, and persist over winter . Leaf sheaths are somewhat compressed, sometimes with long hairs along the margins near the collar. Ligules are less than 0.5 mm long with a few rather long hairs at the sides. Inflorescences are pyramidal, slightly nodding, diffuse panicles with the base frequently concealed in the uppermost leaf. The purplish spikelets are 3-5 mm long. The first glume is awn-like while the second is awn-tipped and slightly longer or at least equal in length to the lemma.
  • Comments: Occasionally found in gardens, this species has a cascade-type appearance from the arching leaves, which are also slightly fragrant. Northern dropseed does very well in well-drained sandy soils. The Ojibway would make a poultice of the roots and apply it to mild skin sores. It also produces excellent forage.

Maps
   
sporobolus_cryptandrus mapSporobolus heterolepis
Additional species in Minnesota:
Sporobolus asper
Sporobolus neglectus
Sporobolus vaginiflorus

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.