Booth, Rhynchospora croydonensis 419 
Key to the Queensland species of Rhynchospora 
1 Inflorescence a compound panicle or clustered in loose corymbs.2 
1. Inflorescence a single, dense head.4 
2 Stems filiform, < 1 mm wide.R. gracillima 
2. Stems stout, 2-15 mm wide.3 
3 Inflorescence a large, loose, compound panicle; style base furrowed on 
both sides; stout plants 70-200 cm high.R. corymbosa 
3. Inflorescence of several small, irregular corymbs; style base not furrowed; 
slender plants to 1 m high, usually less.R. brownii 
4 Style base 0.4-0.6 mm long; bristles whitish, shorter than the achene.R. rubra 
4. Style base > 0.6 mm long; bristles usually > the achene in length.5 
5 Base of the achene and the bristles with no pilose 
hairs (hispid hairs may be present on the bristles only).6 
5. Base of the achene or at least bottom part of the bristles with pilose hairs.9 
6 Achene (not including the style base) < 2 mm long.R. subtenuifolia 
6. Achene > 2 mm long.7 
7 Spikelets < 6 mm long.R. submarginata 
7. Spikelets > 6 mm long.8 
8 Style base furrowed or grooved, achene with broad triangular 
based hairs at the apex; bristles much longer than the style base.R. exserta 
8. Style base not furrowed, achene with rather fine hispid hairs; 
bristles only just longer than the achene and style base.R. heterochaeta 
9 Achene revolute, papillose on the nearly joined margins.R. leae 
9. Achene biconvex or convex, not revolute.10 
10 Style base grooved, curved, or winged adjacent to the achene, often 
setulose on the margins. 11 
10. Style base not grooved, curved or winged.13 
11 Style base long-conical with a groove down the middle.R. longisetis 
11. Style base as broad or broader than the achene, curved, but not grooved.12 
12 Achene papillose (hairs rounded at the ends) over much of its surface, 
pilose hairs covering lower half of the achene.R. pterochaeata 
12. Achene with hispid hairs (pointed at the ends) mainly in the distal half, 
pilose hairs only at the base of the achene.R. croydonensis 
13 Achene > 3 mm long, style base at least 2 mm long.R. longisetis 
13. Achene < 3 mm long, style base <1.5 mm long.14 
14 Achene papillose over most of its surface, bristles unequal in length.R. wightiana 
14. Achene hispid or occasionally papillose, mainly in the distal half, bristles 
equal in length 
R. affinis 
