Phleum pratense


Inflorescence Cross Section

Hudson Bay Trout Pond, 1.5 Miles East of Hudson Bay

The inflorescence is a dense, spike-like, uninterrupted panicle.  The individual panicle branches are difficult to distinguish in a cross sectional view as above.

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)]


Phleum: 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, when present, attached to the rachilla distal to the fertile floret; NOT [Sterile florets 2, attached at base of the fertile floret, either rudimentary and lacking sexual parts, or large and staminate]
Panicles spike-like, dense, uninterrupted; disarticulation below the glumes (occasionally above the glumes early in the season for Phleum species) with spikelets at the top of the rachis falling and revealing the naked rachis in mature plants; calluses glabrous;  NOT [Panicles contracted to open; if spike-like, then disarticulation above the glumes; calluses glabrous or bearded]
Glumes conspicuously awned; lemmas unawned or awned from apex; paleas about as long as lemmas; NOT [Glumes not awned; lemmas awned dorsally; paleas absent or greatly reduced]
Glumes 2.5-4.5 mm long, ciliate-keeled, awned from tip, the awns to 2.5 (3.2) mm long, shorter than or equal to the glumes, stiff; NOT [Glumes 1-2.7 mm long, hispidulous, awned from between minute lobes at tip, the awns 4-10 mm long, much longer than the glumes, hair-like]


Pratense: Answers to key questions leading to this species
Panicles (1.5) 2-14 (17) cm long, 5-10 times longer than wider; glume awns 1-1.5 (2) mm long, often only 1/2 as long as the body of the glume; glume apex usually abruptly truncate at base of awn; anthers 1.6-2.3 mm long; plants introduced, not restricted to CYHI; NOT [Panicles 1-6 cm long, usually 1.5-3 times longer than wide, but sometimes longer; glume awns (0.8) 1-2.5 (3.2) mm long, often about as long as the body of the glume; glume apex obtuse-truncate at base of awn; anthers 1-1.5 (2) mm long; plants native, restricted to CYHI]