455 
Actinotus periculosus (Apiaceae): a new 
perennial species from eastern Australia 
M.J. Henwood 
Abstract 
M.j. Henwood (John Ray Herbarium, School of Biological Sciences (M2), The University of Sydney, NSW 
2006, Australia). 2000. Actinotus periculosus (Apiaceae): a new perennial species from eastern Australia. 
Telopea 8(4): 455-459. A new perennial species, Actinotus periculosus, is described from the 
Leichhardt District of Queensland. A. periculosus is allied to A. helianthi (New South Wales and 
Queensland) and A. schumrzii (Northern Territory), but is separable from these species by its larger, 
deeply dissected leaves and relatively long gynoecial column. A key to all species of Actinotus from 
eastern and central Australia is provided. 
Introduction 
Actinotus as it is currently circumscribed comprises 17 species. The genus is most 
diverse within Australia, and is represented by a single endemic species, A. novae- 
zelandiae (Petrie) Petrie, in New Zealand. Within the Australian Apiaceae, Actinotus is 
recognisable on account of its compressed monocarpic fruit, and its often showy 
involucral bracts forming pseudanthial umbels or capitula. The single-seeded 
monocarp is apparently derived from the more common bicarpellate gynoecium, for 
it initially contains two ovules, one of which subsequently fails to develop beyond a 
rudimentary structure (Magin 1977). 
One of the most widespread Australian perennial species is A. helianthi, which ranges 
from Merimbula (36°54'S, 149°54'E) in southern New South Wales to Rolleston 
(24°27'S, 148°37'E) in Queensland. Two leaf forms can be discerned within 
A. helianthi. Plants from coastal heaths (at the top of sea cliffs or on stable coastal 
dunes) are more robust and have less dissected leaves than plants from woodland 
habitats. When grown in common gardens these morphological differences are 
maintained, thereby appearing to be genetically fixed (von Richter pers. comm.). 
Together with A. schwarzii (restricted to the cliff faces of the MacDonell Ranges; 
Northern Territory), Actinotus helianthi constitutes a morphologically distinct group 
within the genus. Both species are morphologically closely allied and share several 
unique, apparently derived characters namely: more or less filamentous petals, an 
elongated restriction (column) above the ovary and long horn-like nectaries inserted 
at the base of the styles. 
Actinotus helianthi reaches its northern-most limit in the vicinity of the Carnarvon 
range (Queensland). The Carnarvon range is formed in large part by the outcropping 
of Jurassic, Precipice sandstone which marks the northern boundary of the Surat basin. 
The horizontally bedded Precipice sandstone is deeply dissected and forms vertical 
cliffs up to 200 m high. A perennial taxon closely resembling the 'woodland' form of 
A. helianthi has been recorded from the cliffs of the Carnarvon range and is here 
described as a new species. 
