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. 30 species, tropical & temperate regions. Australia: 15 species (9 species endemic), all States.
This genus has at times been included in Machaerina and current research suggests that this is the appropriate treatment. Both have been included in Cladium s.lat. in the past but that is not closely related.
Text by K. L. Wilson (1993); edited KL Wilson (May 2015)
| ||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)||8|
|2||All leaves reduced to flattened mucros; culms 1–3-noded||Baumea juncea|
|Basal leaves well-developed (cauline leaves reduced if present); culms nodeless or 1- (rarely 2-) noded|
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|3||Leaves square to rhomboid (occasionally narrowly so) in cross section, faces concave or occasionally flat||Baumea tetragona|
|Leaves flattened (at least near apex in Baumea rubiginosa) or narrow-rhomboid, faces flat or convex|
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|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||Baumea 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|
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|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|
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|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||Baumea rubiginosa|
|Nut dark red-brown to blackish; spikelets 1-flowered, spread out along branches; glumes 3 or 4; culms nodeless; leaves flat throughout|
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|8||Leaves hollow, perfectly transversely septate||Baumea articulata|
|Leaves pith-filled, occasionally irregularly transversely septate|
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|9||Spikelets few, not in dense clusters, 1-flowered; glumes 2–4 (mostly 3)||10|
|Spikelets numerous, often clustered, 1–4-flowered; glumes 4–6|
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|10||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||Baumea nuda|
|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|
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|11||Nut strongly wrinkled, minutely papillose at base and apex, minutely hispid at extreme apex, 1.3–2.2 mm long||Baumea teretifolia|
|Nut smooth at maturity or somewhat reticulate, minutely hispid at apex, 2.0–4.0 mm long|
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|12||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||Baumea 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|
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