629 
Systematics of Xanthorrhoeaceae sensu lato: 
evidence for polyphyly 
Paula Rudall and Mark W. Chase 
Abstract 
Rudall, Paula and Chase, Mark W. (Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey 
TW9 3DS, United Kingdom) 1996. Systematics of Xanthorrhoeaceae sensu lato: evidence for polyphyly. 
Telopea 6(4): 629-647. This paper reviews the systematics of the ten genera of Xanthorrhoeaceae 
sensu lato in the light of significant new anatomical and molecular data which indicate that it is 
a polyphyletic assemblage. Dasypogon, Calectasia, Kingia and Baxteria belong together in 
Dasypogonaceae in the commelinoid clade, rather than with the other genera in the order 
Asparagales (LUianae). Xanthorrhoea is taxonomically isolated and correctly placed in a monotypic 
family Xanthorrhoeaceae. The family Lomandraceae should include Acanthocarpus, Chamaexeros, 
Lomandra, Xerolirion and Romnalda (not Baxteria), together with other genera (the arthropodioids). 
Introduction 
Ten genera (Table 1) were listed in Xanthorrhoeaceae sensu lato in the Flora of 
Australia (1986). For convenience, this grouping followed Cronquist (1981) and 
Hutchinson (1934), although as several authors (e.g. Waterhouse 1967, Staff & 
Waterhouse 1981) have indicated, the genera concerned form two or three natural 
groupings which are probably not related at the family level. Dahlgren et al. (1985) 
referred six of them to a separate family, Dasypogonaceae, and Calectasia to a 
monotypic family Calectasiaceae, leaving only Xanthorrhoea in Xanthorrhoeaceae, 
although they retained the whole group in the same order, Asparagales (Table 2). 
Romnalda and Xerolirion were described recently and have not been included in most 
treatments. Brummitt (1992), following recommendations from Bedford, listed six of 
the genera as belonging to Lomandraceae Lotsy. Many species of Xanthorrhoea, Kingia 
and Dasypogon are trees or shrubs with remarkably similar vegetative morphology, 
although Xanthorrhoea has a complex 'spike' inflorescence and Kingia and Dasypogon 
have capibilate inflorescences. The other genera are mainly fibrous herbs, with varying 
inflorescence morphology (Table 3). 
A review of the systematics of this group is timely in the light of significant new 
data, both anatomical (Rudall & Caddick 1994, and this paper) and molecular (rbcL: 
Chase et al. 1995a) which indicate that Dasypogon, Calectasia, Kingia and Baxteria 
belong to the commelinoid clade, rather than with Xanthorrhoea and Lomandra in 
Asparagales. The commelinoid clade (Chase et al. 1993), which includes the grasses, 
sedges, rushes, palms and gingers, is fairly well supported (Chase et al. 1995a, 1995b), 
although some analyses exclude the gingers (Stevenson & Loconte 1995). There are 
several characters that distinguish it more or less effectively from other monocots 
(including Asparagales), such as cell wall fluorescence (Rudall & Caddick 1994), 
stomatal type, surface waxes and silica (largely a commelinoid character). 
Furthermore, a secondary thickening meristem distinguishes several groups within 
the asparagoids and is restricted to the asparagoid clade among monocots, although 
not present in all (Rudall 1995). These characters are reviewed here, together with 
other characters of systematic significance in the group, such as pollen (Chanda & 
Ghosh 1976) and ovules (Rudall 1994) (Table 4). 
