Phalaris arundinacea
Reed Canary-Grass

Spikelet, Glumes Removed

Hudson Bay Regional Park

The spikelet consists of two glumes, one central fertile floret, and two much-reduced sterile lateral florets.  The glumes have been removed from this specimen, revealing all three florets.

The following items are taken from keys in Flora of Saskatchewan, Fascicle 4, Grasses of Saskatchewan by Anna L. Leighton and Vernon L. Harms.  Family Poaceae is first divided into tribes, then the tribes are divided into genera, and the genera divided into species.  However, there are a number of tribes that are very difficult to distinguish morphologically.  These are grouped into a large, artificial tribe I call "Multitribe".  Multitribe is then divided into groups, and each group is then divided into genera.  The answers are the the order you would normally work through the keys.

Multitribe: Answers to key questions leading to this tribe. 
Mature inflorescence, if breaking into units, then the units not as below; NOT [Mature inflorescence breaking into spikelet units consisting of a sessile fertile spikelet, a hairy pedicel with or without a sterile spikelet at tip, and a hairy rachis joint, all arising at the same point (a node) in specialized panicle branches called rames]
Spikelets not as below; sterile florets if present, either located distal to the fertile floret(s) on the rachilla or paired and attached at the base of a single fertile floret, not paired with the upper glume as below; lemma and palea variously textured, enclosing the flower or not; disarticulation usually above the glumes; NOT [Spikelets usually dorsally compressed, appearing 1-flowered but containing 1 fertile floret and 1 sterile floret, the latter attached to the base of fertile floret opposite the upper glume, resembling the upper glume, and together with the upper glume enveloping the fertile floret; lower glumes minute (sometimes absent) to 3/4 as long as upper glumes and typically wrapping most of the way around the pedicel at base; fertile floret seed-like with chartaceous-indurate lemma and palea enclosing flower and fruit; disarticulation below the glumes with rare exceptions]
Spikelets 1 to many-flowered, subtended by a pair of glumes (only 1 on lateral spikelets in Lolium); palea margins enclosed or not; plants of dry or wet habitats; NOT [Spikelets 1-flowered, lacking glumes; margins of the palea tightly enclosed by the lemma margins on female or perfect florets; plants of wetlands, often emergent aquatic]
Inflorescence not as below; if a terminal spike, then the lateral spikelets attached edgewise to the rachis with inner (upper) glume wanting (as in Lolium); NOT [Inflorescence a terminal spike with sessile or subsessile spikelets attached broadside at nodes on opposite sides of the rachis]
Lemmas and lemma awns not as below; if lemma indurate and enveloping the floret, then glumes distinctly dorsally compressed and calluses glabrous (as in Milium); NOT [Lemmas stiff to indurate, firmer than the glumes, surrounding the palea and often overlapping along the margins, closed at the tip as well as at the base, often pubescent; lemma awns (caducous or wanting in some species) terete and encircled at the base by the closed tip of the lemma; calluses usually pubescent, rarely glabrous]


Group2: Answers to key questions leading to this group. 
If plants mat-forming, then inflorescences not as below; NOT [Mat-forming annuals or perennials either with clusters of spikelets hidden by sharp-pointed leaves at branch tips, or with pistillate inflorescences consisting of burs partially hidden within expanded leaf sheaths with only the staminate inflorescences exceeding the upper leaves]
Inflorescence not as below, the spikelets usually on pedicels in panicles that range from spike-like to open; if spikelets sessile, then they either have more than 1 fertile floret per spikelet or are not arranged like the teeth of a comb; NOT [Inflorescence consisting of spike-like panicle branches with sessile- subsessile, closely imbricate, regularly-spaced, parallel spikelets all directed toward 1 side of the branch like the teeth of a comb (loosely so in Bouteloua curtipendula); fertile florets 1 per spikelet]
Spikelets with 1 fertile floret; sterile florets if present, attached above or below the fertile floret; NOT [Spikelets with more than 1 fertile floret; sterile florets if present, attached above the fertile florets (Phragmites, with sterile florets attached above and below fertile florets, is an exception)]


Phalaris: Answers to key questions leading to this genus. 
Spikelets pedicellate; inflorescence not as below; NOT [Spikelets sessile and closely oppressed to slender, 3-sided branches; inflorescence usually comprising over 1/2 of the plant height]
Sterile florets 2, attached at base of the fertile floret, either rudimentary and lacking sexual parts, or large and staminate; NOT [Sterile florets, when present, attached to the rachilla distal to the fertile floret]
Sterile florets rudimentary, lacking sexual parts, reduced to slender lemmas shorter that the fertile floret; NOT [Sterile florets staminate and as long as the fertile floret]


Arundinacea: Answers to key questions leading to this species. 
Plants perennial, with creeping rhizomes; panicles usually elongate, 5-20 (40) cm long and tapering at the base with lower branches visible; glumes 0.8-1 mm wide, narrowing to an acute apex; glume keels wingless or winged distally with wings < 0.2 mm wide; sterile florets up to 2 mm long; NOT [Plants annual, without rhizomes; panicles forming a dense, oblong head 1.5-5 cm long and rounded to truncate at base; glumes 2-2.5 mm wide, widening and almost semicircular in outline below the acuminate-mucronate apex; glume keels more broadly and conspicuously winged with wings 0.2-0.6 (1) mm wide; sterile florets 2-4.5 mm long]