Synonyms: Baumea Gaudich. APNI*
Description: Perennials with short rhizomes. Culms erect, tufted, noded or nodeless.
Leaves distichous, isobilateral, glabrous, flattened to terete, or reduced.
Inflorescence panicle-like; involucral bracts culm-like. Spikelets usually clustered, 1–5 bisexual flowers; rachilla persistent. Glumes few, obscurely distichous, keeled, usually lowest 1–3 empty, often shorter than fertile glumes. Perianth absent. Stamens 3. Style 3-fid, deciduous; style base thickened, persistent on nut, fused as hemispherical to conical apex, often minutely hispid or papillose.
Nut trigonous to terete, prominently to obscurely 3-ribbed, smooth at maturity, otherwise irregularly wrinkled.
Distribution and occurrence: World: c. 55 species, tropical & temperate regions. Australia: 17 species (11 species endemic), all States.
This concept now includes Baumea. Both have been included in Cladium s.lat. in the past but that genus is not closely related.
Text by K. L. Wilson (May 2015); edited (May 2019)
Taxon concept:
| | Key to the species | |
| 1 | Leaf blades flat, or 4-angled in cross section, or all reduced to flattened mucros on sheaths | 2 |
| Leaf blades terete or ovate in cross section (rarely somewhat angular or flattened at apex) | 9 |
| 2 | All leaves reduced to flattened mucros; culms 1–3-noded | Machaerina juncea |
| Basal leaves well-developed (cauline leaves reduced if present); culms nodeless or 1- (rarely 2-) noded
Back to 1 | 3 |
| 3 | Leaves square to rhomboid (occasionally narrowly so) in cross section, faces concave or occasionally flat | Machaerina tetragona |
| Leaves flattened (at least near apex in Machaerina rubiginosa) or narrow-rhomboid, faces flat or convex
Back to 2 | 4 |
| 4 | Leaves scabrous | 5 |
| Leaves smooth
Back to 3 | 6 |
| 5 | Glumes 3.0–3.8 mm long; spikelets 3.5–4.5 mm long; nut 1.7–2.0 mm long, 0.8–1.1 mm diam.; culms 1.2–4 mm diam.; sheaths pale brown; leaves with raised 'midvein' even if otherwise flat | Machaerina planifolia |
| Glumes 6–10 mm long; spikelets 6–11 mm long; nut 2.7–3.5 mm long, 1.0–1.6 mm diam.; culms 1–2 mm diam.; sheaths reddish; leaves without a raised midvein
Back to 4 | Machaerina johnsonii |
| 6 | Nut 2.2–4 mm long, 1.2–2.0 mm diam., pale red-brown to bright orange or dark red-brown to blackish | 7 |
| Nut 1.5–2.2 mm long, 1.0–1.3 mm diam., red-brown to black
Back to 4 | 8 |
| 7 | Nut pale red-brown to bright orange; spikelets 2- or 3-flowered, in dense clusters; glumes 5; culms 1- or 2-noded (rarely nodeless); leaves often terete near base | Machaerina rubiginosa |
| Nut dark red-brown to blackish; spikelets 1-flowered, spread out along branches; glumes 3 or 4; culms nodeless; leaves flat throughout
Back to 6 | Machaerina muelleri |
| 8 | Culms 15–35 cm high; leaves 0.7–2.5 mm wide | Machaerina acuta |
| Culms 100–180 cm high; leaves 20–30 mm wide
Back to 6 | Machaerina insularis |
| 9 | Leaves hollow, perfectly transversely septate | Machaerina articulata |
| Leaves pith-filled, occasionally irregularly transversely septate
Back to 1 | 10 |
| 10 | Spikelets few, not in dense clusters, 1-flowered; glumes 2–4 (mostly 3) | 11 |
| Spikelets numerous, often clustered, 1–4-flowered; glumes 4–6
Back to 9 | 12 |
| 11 | Leaves much exceeding culms (to twice as long), c. 0.5 mm diam.; nut 2.0–2.3 mm long, 1.0–1.3 mm diam.; culms smooth | Machaerina abbreviata |
| Leaves shorter than to slightly exceeding culms, 0.7–1.5 mm diam.; nut 2.5–3.5 mm long, 1.3–1.8 mm diam.; culms scaberulous or smooth
Back to 10 | Machaerina gunnii |
| 12 | Nut strongly wrinkled, minutely papillose at base and apex, minutely hispid at extreme apex, 1.3–2.2 mm long | Machaerina teretifolia |
| Nut smooth at maturity or somewhat reticulate, minutely hispid at apex, 2.0–4.0 mm long
Back to 10 | 13 |
| 13 | Nut straw-coloured to whitish, triquetrous, 2.0–2.5 mm long, 1.0–1.3 mm diam.; spikelets not densely clustered; leaf blades and involucral bracts terete at apex | Machaerina arthrophylla |
| Nut pale red-brown to bright orange at maturity, trigonous, 2.2–4.0 mm long, 1.2–2.0 mm diam.; spikelets in dense, discrete clusters on inflorescence branches; leaf blades and involucral bracts flattened at least at apex
Back to 12 | Machaerina rubiginosa |
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