Sporobolus neglectus (Small Dropseed)

Plant Info
Also known as: Annual Dropseed, Puffsheath Dropseed
Genus:Sporobolus
Family:Poaceae (Grass)
Life cycle:annual
Origin:native
Habitat:sun; dry sandy or rocky soil; grasslands, outcrops, roadsides, along railroads, waste places, shores
Fruiting season:August - October
Plant height:4 to 12 inches
Wetland Indicator Status:GP: UPL MW: UPL NCNE: FACU
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: indistinct Cluster type: panicle Cluster type: spike

[photo of terminal panicle] Slender, erect, branching cluster ½ to 2 inches long at the top of the stem, often at least partially enclosed by the uppermost leaf sheath, with smaller panicles in the leaf axils usually fully enclosed by their sheaths. Panicle branches are compound and appressed with several spikelets (flower clusters) per branch. Spikelets are slightly flattened, 1.5 to 3mm (to 1/8 inch) long, often purplish, overlapping along a branch but not tightly crowded, have a single floret, are lance-shaped in outline when immature and more spreading at maturity.

[photo of branch of a panicle enclosed in a sheath] At the base of a spikelet is a pair of bracts (glumes), both thin, hairless, awnless, 1-veined with minute teeth towards the tip end, lance to egg-shaped with a blunt or pointed tip, shorter than the spikelet, the lower glume 1.5 to 2.5 mm long, the upper glume about the same or slightly longer but still shorter than the spikelet. Florets are surrounded by a pair of bracts (lemma and palea), both similar to the glumes but larger, the lemma 1-veined and 2 to 3 mm long, the palea 2-veined and as long as or slightly longer than the lemma.

Leaves and stems: Leaf attachment: alternate Leaf type: simple

[photo of sheath, and leaf hairs] Leaves are mostly alternate, 1 to 2 mm wide at the base with long taper to thread-like tip, usually rolled in along the edges (involute), the upper surface rough, the lower surface smooth, sometimes with a few long spreading hairs near the base along the edges. Lower leaves are up to 4½ inches long, mid and upper stem leaf blades are shorter, usually shorter than the associated sheath. Sheaths are hairless except for a few long, spreading hairs at the tip. The ligule (membrane where the leaf joins the sheath) is a fringe of very short hairs. Nodes are smooth. Stems are multiple from the base, slender, hairless, erect to ascending or prostrate from the base and rising near the tip (decumbent) or rising from a lower node (genticulate). Plants form loose to dense clumps.

Fruit: Fruit type: seed without plume

[photo of mature spikelets from exserted panicle] Exposed spikelets are yellowish to purple at maturity, enclosed spikelets more often white to gray. Mature florets drop off individually leaving the glumes behind on the stalk, but they, too, eventually drop off. The expanding grain (seed) often spits the palea down the middle, falling away free.

[photo of mature spikelets from panicle enclosed in the sheath] Grains are reddish-brown to gray, irregularly egg-shaped to oblong, 1.2 to 1.8 mm long, flattened with a large dark brown or blackish germ on one side.

Notes:

Small Dropseed is a small annual grass that has been collected scattered across Minnesota's praire region. Extremely drought tolerant, it is typically found in sparsely vegetated sand or gravelly soils and rock outcrops. In looking for it, we also discovered it frequently showing up in the gravelly road shoulders along asphalt roadways and urban waste areas. Small and easily overlooked, it is probably distributed more widely than herbarium records indicate.

Without spikelets, it is difficult to distinguish from the related Poverty Dropseed (Sporobolus vaginiflorus); in fact S. neglectus was once consider a variety of S. vaginiflorus (var. neglectus). Both are small-statured annuals with panicles mostly enclosed in their sheaths, may have sparse hairs at the tip of the sheath and/or leaf edges, and are found in the same kinds of habitats. S. vaginiflorus is a somewhat larger plant (to 16 inches tall vs. 12 inches) with longer spikelets (3 to 6 mm vs. 1.5 to 3 mm), longer grains, and the lemmas and paleas are distinctly hairy where S. neglectus is hairless.

According to one report, S. neglectus was recently found invading an isolated section of a national park in Hungary. It “composed a dense stand on 0.2 hectares [.5 acre] in a secondary sandy grassland...introduced here probably in connection with wild game feeding made by illegal hunters coming from Croatia...accordingly, it is a potential invader in the dry sandy grasslands of Hungary”. This brings to mind similar issues here, where suppliers of wild deer feed mixes often include seed of problematic species, either already invasive or potentially so. This is a world-wide problem and one that won't be solved as long as we continue to transport plants and seeds around the globe, simply because it's something to sell.

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More photos

Photos courtesy Peter M. Dziuk taken in Redwood, Renville, Rock and Yellow Medicine counties.

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