Bright green perennial tufts 5-25 cm, with culms overtopping leaves, occasionally stoloniferous; branching intravaginal. Leaf-sheath hyaline, light green to light brown, prominently ribbed, usually smooth, rarely with sparse prickle-teeth. Ligule 1-4.5 mm, truncate to obtuse, denticulate or entire, glabrous. Leaf-blade 2-7 cm × 1.5-2 mm, flat, or folded and c. 0.5 mm diam., abaxially smooth, rarely uppermost leaf scabrid, adaxially prominently ribbed, ribs usually scabrid; margins often entirely smooth, sometimes sparsely, or rarely densely, minutely scabrid, tip fine, blunt, scabrid. Culm erect, internodes glabrous. Panicle (1.5)-2-6 cm, open, laxly oblong to pyramidal, with spreading sometimes flexuous branches; rachis smooth, branches and pedicels smooth or scabrid. Spikelets 2-2.5-(3) mm, usually purplish. Glumes ± unequal, acute to acuminate, keel finely scabrid near tip, margins smooth, rarely scabrid at tip; lower = spikelet, ovate-lanceolate, upper 1.7-2.5-(2.9) mm, elliptic-lanceolate. Lemma 1.5-2 mm, glabrous, faintly 5-nerved, ovate, obtuse; awn (1.5)-2-3 mm, usually middorsal, usually geniculate, sometimes ± straight, slightly projecting beyond glumes. Palea c. 0.5 mm, ovate. Lodicules c. 0.3 mm. Callus with minute hairs. Anthers (0.4)-0.6-0.9 mm. Caryopsis c. 1.5 × 0.7 mm.

Bright green, perennial tufts 5-25 cm tall, with culms overtopping leaves, occasionally stoloniferous; branching intravaginal. Sheaths hyaline, light green to light brown, distinctly nerved, usually glabrous, rarely with sparse prickle-teeth; ligule 1-4.5 mm, truncate to obtuse, denticulate or entire, glabrous throughout; lamina 2-7 cm × 1.5-2 mm if flat, and c. 0.5 mm wide when folded, abaxially smooth, rarely uppermost leaf scabrous, adaxially strongly nerved, usually scabrous on nerves, margins often entirely smooth, sometimes sparsely, or rarely densely, minutely scabrous, tip fine, blunt, scabrous. Culms erect, smooth. Panicle (1.5)-2-6 cm long, open, laxly oblong to pyramidal, with spreading sometimes flexuous branchlets; rachis smooth, branchlets and pedicels smooth or scabrous. Spikelets (excluding awn) 2-2.5-(3) mm, usually purplish. Glumes ± unequal, acute to acuminate, finely scabrous on keel near tip, margins smooth, rarely scabrous at tip, lower glume = spikelet, ovate-lanceolate, upper 1.7-2.5- (2.9) mm, elliptic-lanceolate. Lemma 1.5-2 mm, smooth, glabrous, faintly 5-nerved, ovate, obtuse, always awned; awn (l.5)-2-3 mm, usually middorsal, usually geniculate, sometimes ± straight, slightly projecting beyond glumes. Palea c. 0.5 mm, ovate. Lodicules c. 0.3 mm. Callus with minute hairs. Anthers (0.4)-0.6-0.9 mm. Caryopsis c. 1.5 × 0.7 mm. Endemic.

Gramen perenne, caespitosum, interdum stoloniferum, 5- 25 cm altum, culmis erectis folia superantibus; innovationes intravaginales. Vaginae plerumque glabrae; ligula omnino glabra; laminae plemmque glabrae. Panicula laxa, oblonga vel pyramidalis, (1.5)-2-6 cm long a, ramulis patentibus glabris vel sparsim scabris. Spiculae plerumque purpurascentes. Glumae plus minusve inaequales, acutae vel acuminatae. Lemma leviter 5-nerve, glabrum, semper arista turn; arista plerumque mediodorsalis, nonnihil glumas superans. Palea minuta. Callus pills minutis utraque latere ornatus. A. magellarucae similis lemmatibus semper aristatis, omnibus partibus tamen minor; A. muellerianae etiam proxima cuius spicularum magnitudinem et colorem habet, differt vero glumis minus scabris papillosisque, et ab utraque specie panicula laxiore.