Lolium perenne
Perennial Rye-Grass
Inflorescence
Regina
24-Sep-2025
Note the inflorescence is a panicle.
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]
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 | Bromus: Answers to key questions
leading to this genus.
 | Inflorescence a panicle with all spikelets subtended by 2 glumes; NOT
[Inflorescence a terminal spike; lateral spikelets positioned edgewise
to the rachis and lacking a glume on inside edge] |
 | Spikelets usually pedicellate; if sessile-subsessile, then not
arranged as below; NOT [Spikelets sessile or subsessile on spike-like
panicle branches, or on short secondary branches in dense one-sided
clusters at branch tips] |
 | Rachillas glabrous or pubescent; if pubescent, then hairs much shorter
than the lemmas; panicles and plants not as below; NOT [Rachillas with
silky hairs (4) 6-10 mm long, as long as the lemmas or nearly so;
panicles 15-35 (45) cm long, 8-20 cm wide at maturity, dense, feathery;
plants 10-30 (40) dm tall, with stout, creeping rhizomes and often
forming dense stands] |
 | Glumes < 17 mm long; if glumes longer, then plants perennial; NOT
[Glumes 18-32 mm long, usually exceeding the lemmas; plants annual] |
 | Plants with the below combination of characteristics: Culm
sheaths closed to near summit; leaf blades flat; spikelets 12-40 (55) mm
long; lemmas 7-14 (21) mm long, usually awned, the awns terminal or
subterminal; calluses glabrous; ovaries and caryopses with pubescent
apical appendage; caryopses adnate to paleas at maturity
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 | Inermis: Answers to key questions
leading to this species
 | Plants
perennial; culms solitary to loosely tufted; lemmas unawned or with awns
attached just below the apex and projecting at most 7 (8) mm beyond it;
lemma apex entire, emarginate or bifid with teeth <= 0.5 mm long;
anthers 1-7 mm long; NOT [Plants annual; culms tufted; lemma awns
attached at least 1.5 mm below the apex and 8-18 mm long; lemma apex
bifid with teeth 0.5 to 2 (3) mm long; anthers 0.5-1.5 mm long] |
 | Culms
solitary or a few together from creeping rhizomes; NOT
[Culms loosely tufted, rhizomes absent] |
 | Lemmas
usually glabrous, sometimes sparsely pubescent on margins and rarely on
back; leaf blades glabrous, rarely pubescent or pilose, 11-35 (42) cm
long, 5-15 mm wide; sheaths usually glabrous, rarely pubescent or
pilose; glumes glabrous; NOT [Lemmas
sparsely to densely pubescent on lower back and margins, sometimes
pubescent only on margins and nerves; leaf blades usually pilose and
scabrous adaxially, 9-17 (25) cm long, (3) 4-8 (9) mm wide; sheaths
pilose or glabrous; glumes usually glabrous, occasionally hirsute]
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