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Electronic Flora of South Australia genus Fact Sheet

Family: Gramineae
Poa

Citation: L., Sp. Pl. 67 (1753).

Derivation: Greek poa, grass.

Synonymy: Not Applicable

Common name: Poas.

Description:
Glabrous annuals or perennials; leaf blades usually flat.

inflorescence a panicle; spikelets often compressed laterally, 2-7-flowered; rhachilla disarticulating between the florets; glumes boat-shaped, subequal, 1-3-nerved, shorter than the florets, persistent; lemmas broad, usually obtuse, 5-9-nerved, keeled, awnless, almost always woolly on the lower part of the mid-nerve and marginal nerves; often with hairs (the web) on the callus below the lemmas.

Distribution:  Over 200 species, cosmopolitan, especially in temperate and cool climates.

Biology: No text

Taxonomic notes: In Poa, species are poorly defined. (Keys and species descriptions adapted from Vickery (1970) Contr. N.S.W. natn. Herb. 4:145-243).

Key to Species:
1. Small annuals with soft herbaceous leaves; ligules thinly membranous, glabrous; web (hairs at the base of each floret) absent
 
2. Panicle narrow with the spikelets mostly rather erect and appressed to the branches; lemmas usually 9-11-nerved
P. fax 6.
2. Panicle triangular to ovate with more or less stiffly spreading capillary branches; lemma manifestly 5-nerved
P. annua 1.
1. Perennials; ligules and web various
 
3. Plants bulbous or nodular or otherwise with manifestly thickened internodes at the base
 
4. Plants bulbous at the base with elongate-conical or pear-shaped bulbs, composed of the enlarged and fleshy inner basal leaf sheaths; leaf sheaths glabrous
P. bulbosa 2.
4. Plants nodular or with thickened internodes at the base; leaf sheaths glabrous or pubescent
 
5. Leaf sheaths glabrous; spikelets turgid, very broadly oblong-ovate; culms from a shortly creeping branching rhizome.
P. drummondiana 5.
5. Leaf sheaths pubescent or scabrous; spikelets compressed; plants tufted from a contracted rootstock
P. crassicaudex 4.
3. Plants not bulbous nor manifestly thickened at the base
 
6. Blades pubescent or hirsute on the lower surface
 
7. Blades always inrolled, with dense rather short soft hairs
P. rodwayi 14.
7. Blades often flat, or folded or loosely inrolled
 
8. Blades from densely hairy and greyish-green to rather sparsely hairy, but the hairs generally long and fine, sometimes long and short hairs intermingling; lower internodes not swollen
P. morrisii 11.
8. Blades loosely or densely pubescent; lower internodes often somewhat swollen
P. crassicaudex 4.
6. Blades smooth or scabrous on the lower surface but not manifestly pubescent or hirsute
 
9. Ligule thinly membranous, usually not or scarcely and inconspicuously puberulent or scabrous on the back or ciliolate at the apex, c. 2 mm or more in length or rarely less
 
10. Mature spikelets c. 5-11 mm long, strongly compressed; lemma usually more or less woolly-hairy all over the back in the lower part; sheaths tubular below
P. fordeana 7.
10. Mature spikelets 2.5-6 mm long, compressed but somewhat turgid; lemma hairy on the keel and the marginal nerves in the lower part but not in the internerves; sheaths open
P. pratensis 13.
9. Ligule firmly membranous, usually more or less puberulent or scabrous on the back and/or ciliolate at the apex, 0.1-2 mm long or rarely longer, or more or less reduced to cilia
 
11. Blades (or at least some of them) flat and usually expanded at least when alive, or folded and the margins sometimes inrolled on drying, either broad or narrow
 
12. Stems often leafy and branching from the aerial nodes, or stoloniferous
 
13. Aerial shoots often extravaginal (recognisable by having 1 or more leaves at the base with neither blade nor ligule); lemmas usually pubescent on the internerves on the lower back
P. tenera 15.
13. Aerial shoots usually intravaginal; lemmas glabrous or with sparse hairs on the keels and nerves, very rarely on the internerves
P. umbricola 16.
12. Leaves and shoots mostly from the base, the plants tufted or rhizomatous
 
14. Plants commonly developing horizontal rhizomes which initiate new shoots more or less remote from the parent tussock; extravaginal shoots with scales usually present
 
15. Lower leaf sheaths not purplish; lemmas glabrous on the internerves
P. pratensis 13.
15. Lower leaf sheaths usually exhibiting some greater or lesser degree of purplish colouration; lemmas often more or less pubescent on the internerves
P. clelandii 3.
14. Plants tufted and not normally developing rhizomes
 
16. Panicle usually contracted and more or less linear, or if sometimes with widely spreading branches then usually at least some of the branches short and with spikelets almost to their bases
P. poiformis 12.
16. Panicle at length wide-spreading and branches devoid of spikelets in the lower part
 
17. Sheaths often purplish at the base; loosely ordensely caespitose with numerous extravaginal shoots with firm broad scales
P. clelandii 3.
17. Sheaths not or rarely purplish at the base
 
18. Sheaths scabrous or smooth, not pubescent
P. labillardieri 9.
18. Sheaths usually more or less pubescent or scabrous-pubescent
P. crassicaudex 4.
11. Blades closely folded and/or usually the margins also rolled and overlapping so that the blade is more or less angular-terete, narrow
 
19. Blades more or less rigid
 
20. Small plant with elongate slender rhizomes
P. halmaturina 8.
20. Rhizomes not or rarely developed
P. poiformis 12.
19. Blades not rigid
 
21. Culms at times branching to from fascicles of aerial shoots, or stoloniferous and trailing
P. tenera 15.
21. Tussocks not stoloniferous, aerial shoots not or very rarely produced
 
22. Lemmas hairy in the lower part on the keels and the lateral nerves but usually not on the internerves
 
23. Tussocks generally large and coarse
P. labillardieri 9.
23. Tussocks small and fine-leafed
P. meionectes 10.
22. Lemmas hairy on the internerves on the lower back, with or without longer and/or denser hairs on the keels and the lateral nerves
 
24. Blades beset with very dense fine scabrous emergences
P. rodwayi 14.
24. Blades closely or sparsely beset with scabrous emergences but not so densely and finely as in the preceding
P. crassicaudex 4.

Author: Not yet available


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