Schoenoplectus tabernaemontani
 
Great Bulrush

Apex of Upper Leaf

Regina
20-July-2016

bullet

Acutus: Answers to key questions in Rushes, Bulrushes & Pondweeds plus the remaining Monocots of Saskatchewan by V. L. Harms, A. L. Leighton, and M. A. Vetter leading to this species. The answers are in the order you would normally work through the key. 
bullet

Culms round (terete) or nearly so; inflorescences usually branched, rarely a solitary spikelet (in S. subterminalis); distal leaf blades usually much shorter than their sheaths; if longer than their sheaths, then at most 1 mm wide; scale apices entire or shallowly notched to <= 0.5 mm deep.  NOT [Culms 3-angled (trigonous); inflorescences unbranched, usually a solitary spikelet cluster, sometimes a solitary spikelet; distal leaf blades 2 - 5 times as long as their sheaths and 2 - 9 mm wide; scale apices bifid with a notch 0.5 - 1 mm deep.]

bullet

Inflorescences branched, consisting of 3 - 200 spikelets attached individually or in clusters to branches; achenes plano-convex; culms 50 - 300 cm high, 2 - 10 mm wide near mid-culm; distal leaf blades 1 - 7 mm wide, usually much shorter than their sheaths; scale apices shallowly notched and awned, the awns 0.2 - 2 mm long; plants emergent in wetlands and water to 100 - 150 cm deep throughout much of the province.  NOT [Inflorescences unbranched, consisting of a solitary spikelet; achenes trigonous; culms 20 - 150 cm high, 0.5 - 1 mm wide near mid-culm; leaf blades 0.2 - 1 mm wide, mostly longer than their sheaths; scale apices entire, sometimes obscurely notched or minutely mucronate, not awned; plants submersed or emergent in water to 100 cm deep at Gull Lake south of Lake Athabasca.]

bullet

Culms usually pale green, soft, easily compressed when fresh; scales ovate, shorter than or equal to achenes (exposing them at maturity), often uniformly dark reddish brown to paler orange-brown or stramineous, with margins ciliate and awns up to 0.8 mm long; inflorescences 2 - 4-times branched, with branches to 15 (25) cm long and often spreading and drooping.  NOT [Culms usually dark green, firm, not easily compressed when fresh; scales narrowly ovate to ovate, longer than achenes (covering them at maturity), usually pale stramineous, but +/- prominently striate or marked with dark reddish brown, with margins often appearing more laciniate-fimbriate than ciliate and awns up to 2 mm long (but often broken off); inflorescences at most 2-times branched, with branches to 6 (18) cm long and usually stiffly ascending.]

 

bullet

Schoenoplectus: Answers to key questions in Rushes, Bulrushes & Pondweeds plus the remaining Monocots of Saskatchewan by V. L. Harms, A. L. Leighton, and M. A. Vetter leading to this genus. The answers are in the order you would normally work through the key. 
bullet

Flowers and achenes naked in the axils of scales, not enclosed in a sac; flowers usually perfect (sometimes some flowers imperfect in Cyperus, Rhynchospora and Cladium).  NOT [Flowers and achenes enclosed in a sac (perigynium) borne in the axils of scales; flowers imperfect.]

bullet

Perianth bristles absent or up to 6 per flower; if more than 6, then only somewhat longer than the achenes.  NOT [Perianth bristles usually more than 10 per flower, much longer than the achenes, conspicuously elongated to over 10 mm long in fruit stage and usually obscuring most scales in spikelets.]

bullet

Inflorescence not a solitary, terminal spike; if solitary, terminal and spike-like, then inflorescence +/- terete.  NOT [Inflorescence a compressed, solitary, terminal spike bearing few-flowered spikelets attached in 2 rows.]

bullet

Inflorescence usually with > 1 spikelet; if only 1 spikelet present, then inflorescence bract usually 10 - 200 mm long (but as short as 7 mm in Schoenoplectus subterminalis) and achenes 2 - 3.5 mm long.  NOT [Inflorescence a solitary terminal spikelet; inflorescence bracts absent or up to 8 mm long and only slightly longer than the spikelet; achenes usually <= 2 mm long (up to 2.3 mm in Eleocharis quinqueflora).]

bullet

Achenes lacking a tubercle but sometimes beaked.  NOT [Achenes with a narrowly triangular tubercle.]

bullet

Scales of spikelets spirally arranged; spikelets terete.  NOT [Scales of spikelets 2-ranked; spikelets flattened or 4-sided.]

bullet

Plants without the following combination of characteristics.  NOT [Culms tall and slender, 30 - 100 cm high and 1 - 2 mm wide; inflorescences with stiffly ascending primary and secondary branches supporting 100 - 1,000 spikelets in compact clusters; achenes terete with bases discoid, truncate, impressed and flared.]

bullet

Inflorescences not subtended by leaf-like bracts, the proximal bract terete, trigonous or thickly C-shaped in cross-section and resembling a continuation of the culm (making the inflorescence appear to be attached to the side of the culm although the bract may be pushed aside in Amphiscirpus as the spikelets mature); longest bracts exceeding the inflorescence or not; usually all leaves basal with blades often much shorter than their sheaths.  NOT [Inflorescences subtended by 2 or more leaf-like, erect to spreading bracts; longest bracts exceeding the inflorescence; leaves basal and cauline, or all cauline with cauline leaf blades well developed.]

bullet

Achenes beaked; scales shiny or dull, various shades of brown without strongly contrasting midribs; ligules membranous, lacking hairs; culms and leaves +/- spongy due to presence of air cavities; proximal sheaths not disintegrating into fibers.  NOT [Achenes beakless; scales often glossy (as if lacquered), chestnut-brown with contrasting pale midribs; ligules ciliate usually with some hairs visible along the sheath summit where it joins the blade; culms and leaves wiry and tough, air cavities lacking; proximal sheaths often disintegrating into fibers.]

 

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

bullet

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

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.  

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.