477 
Hopkinsiaceae and Lyginiaceae, two new 
families of Poales in Western Australia, with 
revisions of Hopkinsia and Lyginia 
Barbara G. Briggs and L.A.S. Johnsont 
Abstract 
Briggs, Barbara G. & Johnson, L.A.S. (Royal Botanic Cardens, Mrs Macquaries Road, Sydney, NSW 2000, 
Australia) 2000. Hopkinsiaceae and Lyginiaceae, tivo new families of Poales in Western Australia, xoith 
revisions o/Hopkinsia and Lyginia. Telopea 8 (4): 477-502. Hopkinsia and Lyginia are excluded from 
Restionaceae and the new families Hopkinsiaceae and Lyginiaceae established. DNA sequence 
data from the chloroplast gene rbcL, the trnL intron and tmL-trnF intergenic spacer indicate that 
these genera are more closely allied to Anarthriaceae than to Restionaceae, although differing 
markedly from the former in vegetative morphology' and anatomy. The contrasting results of 
cladistic analyses of DNA sequence data and morphological data are discussed, as are tire reasons 
for excluding these genera from Restionaceae and Anarthriaceae. Extensive descriptions of the new 
families are given and a key' provided to these and related families. The features that they share 
with Restionaceae are considered to be largely plesiomorphic within Poales or associated with their 
occurrence, like many Restionaceae, in conditions of seasonal drought. Occurring in a region of 
great diversity of Restionaceae, their distinctiveness was overlooked until the new DNA evidence 
became available. Distinctive features for Hopkinsia include the ovary' structure, style with stigmatic 
branches that are themselves branched, fleshy pedicels, and fruit with both woody and fleshy 
layers. Distinctive for Lyginia are the oblique epidermal cells and stomates, distinctive 
chlorenchyma structure, fused staminal filaments, seed ornamentation and presence of unusual 
chemical constituents (allose, allosides and fructan-ty'pe oligosaccharides). Both genera also differ 
from Restionaceae in having 2-lobed, 4-sporangiate anthers and pollen of graminoid ty'pe. Two new 
species, H. adscendens from south coastal Western Australia and L. excelsa from tire Cataby region 
north of Perth are described, and the differences in reproductive biology between the species of 
Lyginia are noted. Both the species of Hopkinsia and L. adscendens have vulnerable or endangered 
conservation status. The chromosome number 2 n = 18 is reported in H. adscendens. 
Introduction 
Although Hopkinsia and Lyginia have until now been included within Restionaceae, 
they have long been recognised as differing substantially from other members of that 
family. Gilg-Benedict (1930) placed them, with Anarthria and Ecdeiocolea, in 
Diplantherae, characterised by bithecate anthers, whereas all other Restionaceae have 
unithecate anthers and constituted the Haplantherae. Cutler and Shaw (1965) 
removed Anarthria and Ecdeiocolea from Restionaceae establishing two new families. In 
the absence of molecular data, we have long been aware of major differences between 
Hopkinsia and Lyginia and all other genera then included in Restionaceae (Johnson 
& Briggs 1981), although we regarded them as basal groups within that family. More 
recently, since DNA data became available, we have foreshadowed recognition of the 
new families here described (Linder et al. 1998; Briggs & Johnson 1999; Briggs et al. 
2000; Briggs 2000). 
t Deceased 1 August 1997. 
