Schoenoplectus acutus
 
Viscid Great Bulrush

Achene Adaxial Side

Near White Butte Trails, 14 km East of Regina
19-July-2016

Each achene is associated with six bristles (not all visible here) and three stamens.

Schoenoplectus acutis belongs to the very difficult Schoenoplectus lacustris complex.  In fact, one author (T. Koyama) placed all members of the complex in a single species (Scirpus lacustris).  One other member of the complex (Schoenoplectus tabernaemontani) is found in Saskatchewan and the two species occasionally hybridize.  

Different flora have used different characteristics to differentiate between Schoenoplectus acutus and Schoenoplectus tabernaemontani.  The following table lists all of these.  Note that Budd's Flora directly contradicts Flora of the Great Plains regarding the relative lengths of the scale and achene.

Flora S. acutus S. tabernaemontani
Budd's Flora scales much longer than the achenes scales almost as long as the achenes
Budd's Flora scales narrowly ovate scales broadly ovate
Budd's Flora culms firm culms spongy
Budd's Flora spikelets 1-2 cm long spikelets 3-7 mm long
Flora of Alberta culms firm culms soft
Flora of Alberta inflorescence erect, often compact inflorescence often drooping
Flora of Alberta scales laciniate-fimbriate scales ciliolate
Flora of Alberta scales pale with conspicuous reddish brown striae scales a rich chestnut brown
Flora of Alberta achenes 1.8-3.0 mm long achenes 1.4-2.2 mm long
Flora of the Great Plains spikelets usually in glomerules of 3-8 spikelets usually in glomerules of 2, seldom 3 or single
Flora of the Great Plains spikelets sessile or on short stiff pedicels spikelets on long, lax pedicels
Flora of the Great Plains scales shorter than or equal to achenes scales exceeding the achenes
Flora of the Great Plains culms firm culms soft
Flora of the Great Plains culms dark green culms light green
Flora of North America spikelet scale awns (sometimes broken off) mostly strongly contorted, rarely all straight spikelet scale awns straight to bent
Flora of North America spikelet scale awns 0.52 mm spikelet scale awns  0.20.8 mm
Flora of North America scales wholly or partly pale and prominently spotted at 10X scales (except often midribs) uniformly orangish, or sometimes straw-colored and prominently spotted at 10X
Flora of North America scale flanks sparsely to often densely scabrous scale flanks smooth or very sparsely (rarely densely) scabrous
Flora of North America  some spikelets always clustered. spikelets often all solitary
Flora of North America  widest air spaces in upper 1/4 of culm 0.5 (east)1.5(2.5) (west) mm wide. widest air spaces in upper 1/4 of culm 12.5 mm wide.

Budd's Flora and Flora of Alberta place this species in genus Scirpus.  This is not the current practice, but I have retained the old name in the notes below.

bullet

Acutus: Answers to key questions in Budd's Flora and Flora of Alberta leading to this species. 
bullet

culms stout; NOT [culms slender]

bullet

culms terete; NOT [culms triangular]

bullet

culms firm; NOT [culms spongy, soft]

bullet

cauline leaves usually much reduced; NOT [cauline leaves usually well developed] (FOA)

bullet

sheaths bladeless; NOT [sheaths with blades] (BF)

bullet

involucre green, with the bract or bracts erect or leaf-like, spreading; NOT [involucre consisting of 1 scale-like bract]

bullet

involucre a single erect bract, appearing as a continuation of the stem; NOT [involucre of several leaf-like bracts, spreading]

bullet

NOT [bract small, often shorter than the spikelet]

bullet

inflorescence appearing lateral; NOT [inflorescence appearing terminal]

bullet

inflorescence erect, often compact; NOT [inflorescence often drooping]

bullet

spikelets many; NOT [spikelets generally 1-5]

bullet

spikelets usually in umbellate clusters; NOT [spikelets sessile]

bullet

scales much longer than the achenes; NOT [scales almost as long as the achenes] (BF)

bullet

achenes 1.8-3.0 mm long; NOT [achenes 1.4-2.2 mm long] (FOA)

bullet

scales narrowly ovate; NOT [scales broadly ovate]

bullet

scales pale with conspicuous reddish brown striae; NOT [scales a rich chestnut brown]

bullet

scales laciniate-fimbriate; NOT [scales ciliolate]

 

bullet

Scirpus: Answers to key questions in Budd's Flora and Flora of Alberta leading to this genus. 
bullet

flowers perfect, with spikelets uniform; NOT [flowers imperfect, with staminate and pistillate flowers in same or different spikelets]

bullet

scales of the spikelets several ranked, spirally imbricate; NOT [scales of the spikelets 2-ranked]

bullet

spikelets solitary and terminal or partly lateral; NOT [spikelets in simple or compound terminal umbels] (BF)

bullet

NOT [spikelets in terminal heads or spikes] (FOA)

bullet

scales of the spikelets NOT keeled

bullet

perianth usually present as bristles; NOT [perianth lacking]

bullet

perianth bristles 1-6, rarely lacking; NOT [bristles numerous]

bullet

perianth bristles usually a little longer or shorter than the achene, elongating only in S. hudsonianus; NOT [perianth bristles often 2-3 cm long, silky]

bullet

achenes not enclosed in a perigynium or bract

bullet

base of style not persistent, the achene without a tubercle; NOT [base of the style persistent as a tubercle on top of the achene]

 

bullet

Cyperaceae: Answers to key questions in Budd's Flora  leading to this family. 
bullet

plants not aquatic, or if growing in water, most of the plant emersed; NOT [plants aquatic, floating or submerged, with floating leaves or emersed inflorescence]

bullet

culms usually solid; NOT culms usually hollow]

bullet

leaves three-ranked; NOT [leaves two-ranked]

bullet

inflorescence NOT [a dense, single, cylindrical spike 8-15 cm long, 1-2.5 cm thick], if a single spike, less than 1 cm thick

bullet

flowers not in globular heads; NOT [flowers in globular heads, the upper ones staminate, the lower ones pistillate]

bullet

flowers solitary in the axil of a single bract (scale); NOT [flowers enclosed in two-ranked bracts with the lowest (glumes) empty]

bullet

perianth inconspicuous, not in two whorls; NOT [perianth present, conspicuous, in two series of 3 segments, often brightly colored]

bullet

perianth reduced to bristles; NOT [perianth reduced to minute lodicules or lacking]