Jacobs & Everett, Austrostipa 
581 
Key to genera (modified after Barkworth 1993). 
1 Stamen 1; hilum elliptic; lemma nerves 3 . Anemanthele 
1* Stamens 3; hilum linear; lemma nerves 3 or more . 2 
2 Palea longitudinally grooved, longer than the lemma and protruding from between 
the lemma margins at the lemma apex; lemma marguis involute, fitting into the 
paleal groove; lemma epidermis with very long fundamental cells with thickened 
sidewalls such that the surface appears longitudinally finely ridged; silica cells absent 
from lemma epidermis . Piptochaetium 
2 Palea flat, shorter than or equalling the lemma, lemma margins flat, rarely palea 
grooved and then lemma margins involute, but then palea scarcely protruding at the 
lemma apex (two native Australian spp.); lemma surface smooth or tuberculate, not 
longitudinally ridged; lemma epidermal silica cells present or absent ... 3 
3 Silica bodies in lemma epidermis square or rectangular ... Stipa s.s. 
3* SiUca bodies in lemma epidermis round, oval or absent . 4 
4 Palea < 30% lemma length; lemma heavily silicified, tough, margins tightly 
overlapping; fundamental cells of lemma epidermis very short, much shorter than 
wide . Nassella 
4* Palea usually > 30% lemma length, rarely shorter; lemma membranous, leathery or 
sometimes tough, the margins open, loosely or more or less tightly overlapping; 
fundamental cells of lemma epidermis usually much longer than wide .. 5 
5 Palea coriaceous, not indurate; lemma pale, the margins scarcely enclosing the palea; 
floret terete or slightly dorsally compressed; callus very short and blunt; awn weak 
. 6 
5* Palea indurate; lemma pale or dark; lemma margins enclosing the palea; callus often 
pungent; awn robust . 9 
6 Leaf blades filiform, < 0.5 mm wide; plants of boggy alpine and subalpine habitats 
. Ptilagrostis 
6* Leaf blades not filiform, usually > 0.5 mm wide; plants of various habitats . 7 
7 Palea pubescent, shorter than or equal to the lemma but not prow-bpped . 
. Achnatherum 
7* Palea glabrous, prow-tipped, as long as the lemma . 8 
8 Florets dorsally compressed; lemma margins not overlapping, the palea exposed, 
at least in part . Piptalherum 
8* Florets terete or laterally compressed; lemma margins often overlapping, concealing 
the palea . Oryzopsis 
9 Lemma white, yellow, brown, red-brown, purple or black at maturity, often with 
brownish hairs; florets 2—12 mm long; awn 1.4—20 cm long; lemma epidermis always 
with round to oval silica bodies . Austrostipa 
9* Lemma white or cream-coloured, with sparse white hairs; florets > 7.5 mm long; 
awn > 8 cm long; lemma epidermis without silica bodies . Hesperostipa 
As well as the 62 Australian species of Austrostipa (including one new species described 
here) there are (Jacobs et al. 1995) three species ot Achnatherum (one new combination 
