N.S. Lander, Olearia (Asteraceae: Aslereae) 
145 
Olearia fluvialis Lander, sp. nov. (Figure 2) 
Species nova ad Olearia seclionem Eriotrichum pertinens; foliis disperis, sessilibus, planis, 
anguste ovatis, minute bullatis, integris, et capitulis hcterochromis conspicue radiatisque facile 
distinguitur. 
Typus: Fortescue River, Western Australia, anno 1895, W. Cussock s.n. (holo: MEL 1547238). 
Shrub to 0.6 m high. Vestiture of vegetative surfaces with long, intricate, articulate, 
multicellular, uniseriate, simple eglandular hairs and minute multicellular, biseriate, capitate 
glandular hairs. Stems erect, smooth, subglabrous or arachnoid, pale green, striate. Leaves 
alternate, scattered, ascending, sessile; lamina flat, narrowly ovate, 2.0-9.0 x 1. 0-2.0 mm, 
concolorous, green, minutely bullate; venation indistinctly reticulate with prominent midvein; 
vestiture uniformly subglabrous or weakly arachnoid; texture herbaceous; base rounded; margin 
entire, flat; apex narrowly acute. Heads terminal, solitary, pedunculate, conspicuously radiate, 
8.8-12.5 mm diameter; disc 5-8 mm diameter. Peduncle to 76 mm long, subglabrous or arachnoid, 
with several lcaflike bracts grading into those of the involucre. Involucre obconic; bracts 
6-7-seriate, 1. 7-9.2 x 0.9-1.3 mm. Outer involucral bracts somewhat cymbiform, narrowly 
triangular or linear; stereome pale green, smooth and subglabrous or weakly arachnoid abaxially; 
margin membranous, fimbriaie; apex narrowly acute or acute. Inner involucral bracts somewhat 
cymbiform, linear; stereome pale green, smooth and glabrous or subglabrous with only eglandular 
hairs abaxially; margin membranous, fimbriate; apex narrowly acute. Receptacle flat. Ray florets 
12-14, uniseriate, female, 6.8-9.7 mm long; tube subglabrous with multicellular, biseriate, simple 
eglandular hairs scattered apically; limb elliptic or ovate, 3.8-4.5 x 0.9- 1.2 mm, white or mauve, 
glabrous, broadly acute or obtuse apically; staminodes absent; slylar arms filiform, 1.2-1. 8 mm 
long. Disc florets c. 12, infundibular, 5.7-6.8 mm long, yellow, glabrous; lobes 5, 0.7-0.8 mm long, 
acute; anthers 2.3-2.6 mm long, basally minutely sagittate and shorter than the filament collar, with 
narrowly ovate, sterile terminal appendage; filament collar 0.4-0.5 mm long; stylar arms oblong, 
1. 5-1.7 mm long, with narrowly halfconic, sterile terminal appendage bearing botuliform collecting 
hairs above the stigmatic lines. Achene narrowly obovoid, 1 .5-2.9 x 0.5-1.0 mm, brown, densely 
sericeous with duplex hairs, distinctly 6-7 ribbed; carpopodium conspicuous, central. Pappus 
uniseriate, with 31-40 minutely barbellatc bristles subcqual to the tubular florets. 
Flowering period. April. 
Distribution. Known from only a single locality in the Hamersley Range National Park between 
22-23° S and 1 18-1 19° E in the Fortescue District, Eremaean Botanical Province, Western Australia 
(Figure 8). 
Habitat. On iron rich alluvium. 
Conservation status. Since it is restricted to a single known population, this species appears to 
warrant the category 2V in the coding system of Leigh et al. (1981). 
Other specimen examined. Wittenoom area [precise locality withheld], J.V. Blockley 148 (KPBG, 
PERTH). 
Etymology. The specific epithet draws attention to the riverine habitat favoured by this species. 
Notes. The intricate, arachnoid eglandular hairs and the glandular hairs found on the vegetative 
parts of plants of this species place it in Olearia section Eriotriche Archer ex Benth. 
In the handbook of Grieve & Blackall (1975) specimens of this species will key (with some 
difficulty) to O. propinqua S. Moore (= O. pimeleoides (DC.) Benth. sens, strict.). O. fluvialis can 
be distinguished from the latter by its heads, which are conspicuously pedunculate rather than 
