Booth, Rhynchospora croydonensis 
Taxonomy 
Rhynchospora croydonensis R. Booth, sp. 
nov. similar to Rhynchospora pterochaeta 
F.Muell. but differs in the achene surface 
that has scattered hispid hairs (versus densely 
papillose), and hairs on the hypogynous 
bristles at the very base of the bristles (versus 
densely pilose for half their length). Typus: 
Queensland. Burke District: 6.5 km along 
Coralie Road from Croydon - Claraville 
Road junction, 22 April 2011, K.R. McDonald 
KRM10937 (holo: BRI [AQ759401]; iso: 
NSW). 
Rhynchospora sp. Croydon (S.L.Everist 
5384); R.Booth in Bostock & Holland (2014). 
Annual or short lived perennial 20-45 cm 
tall; culms tufted, 3-angled, trigonous, 
striate, 0.6-1.3 mm wide, glabrous. Lamina 
flat or conduplicate, 1-3 mm wide with long 
ciliate hairs when young, glabrescent. Ligule 
membranous. Involucral bracts ciliate on 
the margins, longer than the inflorescence. 
Inflorescence a single dense head, 1.2-1.5 cm 
long by 2-2.5 cm wide. Spikelets lanceolate or 
linear-lanceolate, 7.5-10 mm long, pale brown 
to brown. Perianth present as 6 hypogynous 
bristles, unequal in length, longer than the nut 
and style base, antrorsely scabrid, plumose at 
the base, glabrous above. Glumes distichous, 
6-7, narrowly ovate or ovate-lanceolate, 2-10 
mm long, 1.2-1.8 mm wide, coloured straw or 
light brown to brown, glabrous, keeled or with 
the midrib distinct, not nerved; apex acute; 
margin glabrous; rachilla wingless. Style 
deciduous, entire, glabrous. Achene with a 
persistent style base, not grooved, 2.4-3 mm 
long, as broad or broader than the achene and 
longer than, or equalling the achene; margins 
winged, setulose; stramineous, or yellow- 
brown. Achene obovoid, biconvex, lenticular, 
or concave-convex; 2.2-3 mm long, 1.3-1.6 
mm wide, not ribbed; surface smooth or with 
417 
a faint cell pattern, with hispid hairs mainly in 
the distal half, pilose hairs only at the base of 
the achene. Fig. 1. 
Additional specimens examined : Queensland. Burke 
District: Cothilda Station, May 2001 Turpin GPT872 
(BRI); between Croydon and Gilbert River, May 1954, 
Everist 5384 (BRI). Cook District: Staaten River 
NP, c. 35 km W of Bulimba Homestead, 150 km W 
of Chillagoe, Sep 2013, Leitch ODA004939 (BRI); 
Fishermans Waterhole, Walsh River, N of Chillagoe, 
Mar 2005, McDonaldKRM3936a (BRI); Bulleringa NP, 
Jul 2006, Lovatt TH9249 (BRI); 79 km from Georgetown 
on Croydon Road, Apr 1996, Forster PIF19012b & Ryan 
(BRI); 23 miles [38.3 km] SE of Croydon township, Jul 
1954, Speck 4719 (CANB). 
Distribution and habitat: Rhynchospora 
croydonensis is endemic to northern 
Queensland where it has been found between 
Croydon and the Gilbert River in the south, 
Staaten National Park in the north, and west 
to Bulleringa National Park (Map 1). Plants 
usually grow in drainage lines in sandy soils 
often with Melaleuca viridiflora Sol. ex 
Gaertn. var. viridiflora. 
Affinities: Rhynchospora croydonensis is 
closely related to R. pterochaeta , which it 
differs from most obviously in the achene 
characters: R.pterochaeta being papillose over 
much of its surface, while R. croydonensis 
has hispid hairs, mainly in the distal part of 
the achene. 
Conservation status: There are only nine 
collections of Rhynchospora croydonensis 
and its geographic range is not large. This 
sedge has been found in Bulleringa and 
Staaten River National Parks and is likely to 
be widespread in its seasonally ephemeral 
habitat dominated by annual or geophytic 
species. It is not considered to be threatened 
and a Least Concern conservation status is 
recommended. 
Etymology: The epithet is from the town 
of Croydon in the Gulf of Carpentaria near 
where this species was first collected. 
