Poa compressa L.
|
Common name
Canada Bluegrass
Derivation
Poa L., Sp. Pl. 67 (1753); from the Greek poa (grass, especially
as fodder).
compressa- from the Latin comprimo (squeeze together). Culms flattened.
Published in
Sp. Pl. 69 (1753).
Habit
Perennial, culms solitary or tufted. Rhizomes elongated. Basal leaf sheaths
glabrous. Young shoots extravaginal. Culms erect or geniculately ascending,
slender, 1060 cm tall, wiry, 46-noded. Mid-culm internodes elliptical
in section, smooth, glabrous. Lateral branches simple or branched. Leaves mostly
basal. Leaf-sheaths smooth. Ligule an eciliate membrane or a fringed membrane,
0.41.3(3) mm long, truncate or obtuse. Leaf-blades flat or conduplicate,
212 cm long, 14 mm wide, rigid or firm. Leaf-blade surface smooth
or scaberulous, glabrous. Leaf-blade apex abruptly acute.
Inflorescence
Inflorescence compound, a panicle. Panicle open or contracted, oblong or ovate,
dense or loose, 1.210 cm long, 0.53 cm wide. Primary panicle branches
ascending, 24-nate, bearing spikelets almost to the base. Panicle branches
straight, angular, scaberulous.
Spikelets
Spikelets solitary. Pedicels 0.32 mm long. Fertile spikelets many flowered,
comprising 310 fertile florets, with diminished florets at the apex,
elliptic or oblong or ovate, laterally compressed, 38 mm long, breaking
up at maturity. Spikelets disarticulating below each fertile floret. Rhachilla
internodes obscured by lemmas, smooth. Floret callus glabrous or woolly.
Glumes
Glumes persistent, similar. Lower glume ovate, 1.63 mm long, 90100%
length of upper glume, membranous, 1-keeled, 3-nerved, midnerve scabrous. Lower
glume apex acute. Upper glume ovate, 1.63 mm long, 90100% of
length of adjacent fertile lemma, membranous, 1-keeled, 35-nerved, midnerve
scabrous. Upper glume apex acute.
Florets
Fertile lemma oblong, oblong in profile, 23 mm long, membranous, much
thinner above, 5-nerved. Lemma midnerve ciliate, hairy below. Lemma lateral
nerves obscure, stopping well short of apex. Lemma margins ciliate, hairy below.
Lemma apex acute. Palea 100% of length of lemma. Palea keels scabrous. Apical
sterile florets resembling fertile though underdeveloped. Lodicules 2, membranous.
Anthers 3, 1.21.9 mm long. Grain with adherent pericarp. Hilum punctiform.
Continental Distribution:
Europe, Africa, Temperate Asia, Tropical Asia, Australasia, North America, South
America.
Australian Distribution:
New South Wales, Victoria, Tasmania.
New South Wales: Central Coast, Northern Tablelands, Central Tablelands, Southern Tablelands, Central-Western Slopes. Victoria: Eastern Highlands, Gippsland Plains, Wilsons Promontory. Tasmania: West Coast, East Coast.
Classification. (GPWG
2001):
Pooideae: Poeae
Notes
Introduced. Widespread, native to Europe. Coloniser of waste lands and disturbed
ground, often on shallow well-drained soils, also a weed of pasture.
Inflorescence (scanned specimen)
© Queensland Herbarium
AQ 293968
by D.Sharp