Vascular Plants of North Carolina
Account for Slender Spikegrass - Chasmanthium laxum   (L.) Yates
Members of Poaceae:
Members of Chasmanthium with account distribution info or public map:
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Section 5 » Order Cyperales » Family Poaceae
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Author(L.) Yates
DistributionFrom the Outer Banks/barrier islands to the upper Piedmont; scarce in the Mountains proper. Seemingly absent from most of the northern and central mountains.

NY, KY, and OK south to southern FL and eastern TX.
AbundanceCommon throughout, except uncommon on the Outer Banks/barrier islands and rare in most of the Mountains; can be fairly common in southern mountain counties.
HabitatMoist to seasonally wet savannas and flatwoods, pocosin ecotones, streamhead ecotones and seepages, small stream swamps, creeksides/streamsides, swamp forests.
PhenologyFlowering and fruiting June-October.
IdentificationSlender Spikegrass tends to grow in patches or clumps of plants from short horizontal rhizomes. The leaves are about 1 foot long and 3-7 mm wide. The flowering stem is 2-3 feet tall; the upper half is the actual inflorescence, a series of erect branches with rather crowded spikelets (occasionally sparse). Each spikelet usually has 3-5 florets. Longleaf Spikegrass (C. sessiliflorum) is very similar, but it usually has more florets per spikelet (4-7 instead of 3-5 florets in C. laxum), has pilose leaf sheaths (vs. smooth in C. laxum), and occupies mesic slopes and flats instead of wet forests and other damp ground habitats.
Taxonomic CommentsOlder references named this as Uniola laxa.

Other Common Name(s)Slender Woodoats. Most references use "woodoats" for many members of Chasmanthium; however, NatureServe and Weakley (2018) use "spikegrass" as the main group name -- for species with narrow, spike-like inflorescences. In general, "oats" as part of the common name is best used for species with very large and flattened spikelets, as in C. latifolium [River Oats] and Uniola paniculata [Sea Oats].
State RankS4 [S5]
Global RankG5
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B.A. SorrieSandhills Game Land, moist ecotone of streamhead, July 2009. ScotlandPhoto_natural
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