Flora of New Zealand Series

Type species: P. pratensis L.

Tufted annuals or perennials, sometimes forming large tussocks, often rhizomatous or stoloniferous; branching intra- or extravaginal. Leaf-sheath open or closed, membranous to coriaceous. Ligule mem-branous, entire or rarely lacerate, sometimes ciliate, sometimes reduced to a truncate, minutely ciliate rim. Leaf-blade persistent or disarticulating at ligule, flat, folded, sometimes setaceous or filiform, margins sometimes inrolled, coriaceous, or soft and flaccid, tip hooded, or finely acute to ± pungent. Culm unbranched above. Inflorescence an open or contracted panicle. Spikelets 2-several-flowered, pedicelled, laterally compressed, uppermost florets reduced, disarticulation above glumes and between florets; rachilla prolonged; ⚥, dioecious, gynomonoecious. Glumes subequal or unequal, usually < adjacent lemmas, keeled, acute to subobtuse; lower 1-3-nerved, upper 3-(5)-nerved. Lemma (3)-5-(7)-nerved, keeled, obtuse to acute to acuminate, awnless but midnerve occasionally slightly excurrent, nerves shortly hairy in lower half, or short scabrid, or glabrous, internerves variously short hairy, scabrid, glabrous, or occasionally papillose. Palea ≈ lemma, keels and interkeel scabrid to ciliate, or glabrous. Callus short, with loose woolly hairs or glabrous. Lodicules 2, glabrous, occasionally hair-tipped. Stamens 3. Gynoecium: ovary glabrous; styles 2, free; stigmata plumose. Caryopsis ellipsoid; embryo < ⅓ length of caryopsis; hilum punctiform or shortly elliptic, < ½ length of caryopsis.

SYNOPSIS

• A.
• • Massive tussocks, or large or sometimes small tufts; leaf-blades persistent, ± tough, wide and flat, or folded, tips often semi-pungent; ligule entire or lacerate; panicle branches usually smooth; plants sexually dimorphic, dioecious or gynomonoecious, rarely (P. tennantiana) ⚥; anthers > 0.6 mm
  • 1.
  • • Large tussocks or sward-forming (P. ramosissima); panicle contracted; southern and subantarctic islands:
    • 16. cookii, 18. foliosa, 37. ramosissima 45. tennantiana
  • 2.
  • • Tufted, sometimes long-rhizomatous; panicle open or ± contracted; subalpine to alpine South Id (and North Id P. novae-zelandiae):
    • 32. novae-zelandiae, 38. schistacea, 43. subvestita 44. sudicola
• B.
• • Short tussocks, or small or sometimes large tufts; leaf-blades disarticulating at ligule, wiry, folded with inrolled margins, tips acuminate or naviculate; ligule apically glabrous; panicle open or contracted, branches scabrid or smooth; anthers > 0.6 mm, rarely shorter (P. maniototo):
  • 1. acicularifolia, 5. astonii, 14. colensoi 19. hesperia, 29. maniototo
• C.
• • Large tussocks, clumps, or tufts, erect or trailing down banks, rarely slender (P. pusilla); leaf-blades persistent, usually folded, sometimes flat, tips often semi-pungent, or naviculate; ligule a truncate rim, minutely ciliate; panicle open, sometimes contracted, branches usually scabrid; anthers > 0.6 mm
  • 1.
  • • Branching intravaginal:
    • 12. cita, 13. cockayneana, 25. labillardierei 27. litorosa, 40. sieberiana
  • 2.
  • • Branching extravaginal:
    • 2. anceps, 11. chathamica, 35. pusilla 48. xenica
• D.
• • Tufted, or rhizomatous or stoloniferous (rarely in compact tufts, P. bulbosa, with culms swollen at base), perennial or annual; leaf-blades persistent, usually flat, sometimes folded; ligule apically glabrous or ciliate; panicle open, sometimes compressed, branches scabrid or smooth; anthers > 0.6 mm (except P. infirma):
  • 3. annua, 4. antipoda, 9. bulbosa 15. compressa, 17. dipsacea, 22. infirma, 31. nemoralis, 33. palustris, 34. pratensis 47. trivialisalpina
• E.
• • Tufted, sometimes shortly rhizomatous or stoloniferous; leaf-blades persistent, flat or folded, sometimes filiform; ligule apically glabrous (ciliate in P. intrusa); panicle open, branches scabrid or smooth
  • 1.
  • • Panicle branches slender but firm, spikelets relatively large and conspicuous; anthers usually > 0.6 mm:
    • 6. aucklandica, 10. celsa, 23. intrusa 24. kirkii, 28. maia, 42. sublimis
  • 2.
  • • Panicle branches and spikelets delicate; anthers 0.2-0.6 mm:
    • 7. breviglumis, 20. imbecilla, 30. matthewsiiremota
• F.
• • Tufts small, compact (rarely stoloniferous P. senex) with culms often almost entirely included within leaf-sheaths; leaf-blades persistent, often stiff and inrolled, or flat; ligule apically glabrous (ciliate in P. spania); panicle open or contracted, branches scabrid, or smooth (P. pygmaea); anthers 0.2-0.6 mm (> 0.6 mm in P. pygmaea and P. spania)
  • 1.
  • • Internerves of lemma silky haired for ½ length or more:
    • 26. lindsayi, 36. pygmaea, 41. spania 46. tonsa
  • 2.
  • • Internerves of lemma smooth, scabrid or papillose, rarely a few hairs near base:
    • 8. buchananii, 21. incrassata, 39. senex

Cosmopolitan, c. 500 spp. Endemic spp. 37, indigenous sp. 1 - P. cookii; naturalised spp. 10; transient spp. 2.

Poa occurs throughout the N.Z. botanical region, but has a marked southern and subantarctic centre of speciation. New Zealand spp. were revised by Edgar, E. N.Z. J. Bot. 24: 425-503 (1986); two new endemic spp. were added by Edgar, E. and Connor, H. E. N.Z. J. Bot. 37: 63-70 (1999) and one by Edgar and Molloy in Molloy, B. P. J. et al. N.Z. J. Bot. 37: 41-50 (1999). Zotov, V. D. Rec. Dom. Mus. 5: 101-146 (1965), presented a synoptic treatment of the grasses of the Subantarctic Islands including 12 endemic, 1 indigenous, and 3 naturalised spp. of Poa.

Endemic spp. of Poa are found from sea level to high alpine areas, usually in grassland or on open rocky ground, cliffs, and scree, occasionally in open forest, or in seepages. Naturalised spp. from Europe occur mainly on roadsides and in waste places. Cosmopolitan P. annua is a common weed throughout. Poa pratensis, Kentucky bluegrass, is grown as a pasture grass in both North and South Is, and is locally common in tussock grassland, sometimes at high altitudes. Two Australian tussock-forming spp. occur in modified tussock grassland.

Edgar (1986 op. cit. p. 427) discussed the apparent relationship of subantarctic P. ramosissima and P. cookii to the large tussock sp. P. flabellata of southern South America, South Georgia, Falkland and Gough Is. The monotypic genus Parodiochloa C.E.Hubb. based on Poa flabellata, is distinct from Poa only in the elongated unbranched sparsely papillate stigmas and Clayton and Renvoize (1986 op. cit.) treat Parodiochloa as a synonym of Poa.

Poa triodioides (Trin.) Zotov, formerly referred to Festuca as F. littoralis Labill., is now included within Austrofestuca (Tzvelev) E.B.Alexeev.