Description: Annuals or perennials, often with branching stems.
Leaves with ligule a membranous or ciliolate rim; blade folded in bud. Panicle of 1-sided racemes on a primary axis, secondary branching rare; rachis of each raceme or branch extending as a bristle beyond the point of attachment of the last spikelet.
Spikelets solitary or paired, falling entire at maturity. Florets 2, dissimilar, the lower either male or sterile; palea present or absent; upper floret bisexual. Lower glume abaxial, smaller than the upper, 0–7-nerved; upper glume usually subequal to the spikelet, 5–15-nerved; rarely both glumes much reduced. Lower lemma equal to the upper glume in shape and size, 3–11-nerved. Upper lemma acute or apiculate, smooth, nerveless or obscurely nerved, ± transversely rugulose, the margins embracing the sides of the palea; palea subequalling the lemma and similar in texture, 2-keeled.
Distribution and occurrence: World: c. 40 species, tropical regions. Australia: 22 species (native), all mainland States.
Text by S. W. L. Jacobs & C. A. Wall Taxon concept:
Taxa not yet included in identification key
Paspalidium grandispiculatum
| Key to the species | |
1 | Lower floret with a palea almost as long as the lemma; spikelets 3.5–4.5 mm long; erect tufted perennial | Paspalidium globoideum |
| Lower floret with a very small palea or empty; spikelets usually not more than 3.5 mm long; tufted annuals or perennials | 2 |
2 | Outline of spikelet distinctly constricted about 30% of its length from the base (if viewed from the back) because the upper glume and lemmas are very narrow at the base and the lower glume bulged at the base (i.e. slightly inflated); spikelets irregularly arranged on the racemes | 3 |
| Outline of the spikelet not noticeably constricted about 30% of its length above the base (although the fertile floret itself sometimes constricted as in Paspalidium distans) Back to 1 | 6 |
3 | Racemes with a solitary spikelet or lower racemes unequally once- or few-branched, each branch with a single spikelet; spikelets 3–3.75 mm long; slender, branched annual | Paspalidium rarum |
| Racemes with more than 1 spikelet; spikelets mostly less than 3 mm long; densely tufted perennials Back to 2 | 4 |
4 | Spikelets lanceolate in outline and to 1 mm wide, 2–2.5 mm long; culms usually slender and glabrous; nodes glabrous | Paspalidium criniforme |
| Spikelets elliptic and usually more than 1 mm wide, 2–3.5 mm long; culms more robust; nodes more or less hairy Back to 3 | 5 |
5 | Fertile floret finely transversely rugose; culms and nodes smooth to scabrous or pubescent; spikelets 2–2.75 mm long | Paspalidium gracile |
| Fertile floret more or less coarsely transversely rugose; culms and nodes mostly pubescent or scabrous-pubescent, often with a few long hairs; spikelets 2.25–3.5 mm long Back to 4 | Paspalidium constrictum |
6 | Slender annual; racemes with few spikelets 1.8–2.2 mm long, that are not regularly arranged in distinct rows | Paspalidium clementii |
| Tufted perennials; racemes with many spikelets arranged in 2 rows usually on 1 side of the rachis Back to 2 | 7 |
7 | Spikelets usually 2.5 mm or more long, if less than 2.5 mm then plants lax, decumbent and usually rooting at the lower nodes | 8 |
| Spikelets less than 2.5 mm long Back to 6 | 10 |
8 | Lower racemes often as long as or longer than the internodes of the primary axis; spikelets 2.5–3 mm long, plano-convex but not bulging on 1 side, and standing erect on the racemes; lower glume not inflated | Paspalidium jubiflorum |
| Lower racemes usually shorter than the axis internodes; spikelets 2.5–3 mm long, bulging on 1 side and diverging from the raceme axis as they mature; lower glume inflated at the base Back to 7 | 9 |
9 | Culms rigid, wiry, arising from knotted rhizomes, spikelets often widely gaping; upper glume 7–9-nerved | Paspalidium gausum |
| Culms weak and easily compressed, often geniculate and rooting at the lower nodes, arising from a dense rootstock, plants lax; spikelets not gaping; upper glume 5–7-nerved Back to 8 | Paspalidium aversum |
10 | Leaves hirsute with long, white, tubercle-based hairs that extend to the inflorescence axis; spikelets 1.5–2.0 mm long | Paspalidium albovillosum |
| Leaves glabrous or, if some hairs present, these do not extend to the inflorescence axis; spikelets 1.7–2.2 mm long Back to 7 | 11 |
11 | Leaves with blade to 1.5 mm wide when expanded; loosely rolled; lower glume not inflated | Paspalidium caespitosum |
| Leaves with blade flat (sometimes loosely rolled on drying) and to 4 mm wide; lower glume inflated at the base Back to 10 | 12 |
12 | Fertile lemma coarsely transversely rugulose (with distinct ridges); plants slender with weak culms | Paspalidium breviflorum |
| Fertile lemma finely transversely rugulose (ridges less distinct); culms erect or geniculate, radiating from a densely tufted rootstock Back to 11 | Paspalidium distans |
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