Schoenoplectus tabernaemontani
 
Great Bulrush

Leaf Blade, Adaxial Side

Hudson Bay Regional Park
02-July-2013

Schoenoplectus tabernaemontani 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 acutis) is found in Saskatchewan and the two species occasionally hybridize.  The specimen illustrated here does not have all the attributes of S. tabernaemontani.  However, I have identified it as S. tabernaemontani because the spikelets are mostly either single or found in glomerules of two or three spikelets, rather than in glomerules of three to eight spikelets.  In addition, the spikelets are generally less than one cm long and the scales are a generally a rich chestnut brown (not pale with red spots).

Different flora have used different characteristics to differentiate between Schoenoplectus tabernaemontani and Schoenoplectus acutus.  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.

This species is now called Schoenoplectus tabernaemontani.  However, both Budd's Flora and Flora of Alberta called it Scirpus validus and this is what is used in the answers to the keys listed below.

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Validus: Answers to key questions in Budd's Flora and Flora of Alberta leading to this species. 
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culms stout; NOT [culms slender]

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culms terete; NOT [culms triangular]

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culms spongy, soft; NOT [culms firm]

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

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

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

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

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NOT [bract small, often shorter than the spikelet]

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inflorescence appearing lateral; NOT [inflorescence appearing terminal]

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

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spikelets many; NOT [spikelets generally 1-5]

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spikelets usually in umbellate clusters; NOT [spikelets sessile]

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

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

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scales broadly ovate; NOT [scales narrowly ovate]

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

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scales ciliolate; NOT [scales laciniate-fimbriate]

 

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Scirpus: Answers to key questions in Budd's Flora and Flora of Alberta leading to this genus. 
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flowers perfect, with spikelets uniform; NOT [flowers imperfect, with staminate and pistillate flowers in same or different spikelets]

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

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

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

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scales of the spikelets NOT keeled

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perianth usually present as bristles; NOT [perianth lacking]

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

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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]

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achenes not enclosed in a perigynium or bract

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

 

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

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culms usually solid; NOT culms usually hollow]

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

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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

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

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

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

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