Rudall & Chase, Systematics of Xanthorrhoeaceae sensu lato 
633 
For silica analysis, thick leaf sections were dried using a Balzers CPD 020 critical 
point drier, then mounted onto stubs and carbon-coated using a Fisons TB 500 
Temcarb carbon coater. They were then examined using a Link Analytical QX 2000 
X-ray analyser and a Cambridge Instruments Stereoscan 240 SEM. 
Results 
Secondary thickening meristem (STM) 
Radially-aligned vascular bundles, derived from an STM, are present in the woody 
underground rhizome of several species of Lomandra (Fig 2a), including L. confertifolia, 
L. filifontiis, L. juncea, L. obiiqiia and L. preissii. Fahn (1954) also reported an STM in 
Lomandra, but the observation has been discounted by some authors because the 
genus is herbaceous. Xanthorrhoea also has an STM, but an STM is lacking in Kitigia 
and Dasypogon (Waterhouse 1967). 
Leaf anatomy 
In previous anatomical works on this group, Fahn (1954, 1961) described the leaf 
anatomy of Acanthocarpus preissii, Baxteria australis, Calectasia (two species), 
Chamaexeros, (two species), Dasypogon (two species), Kingia australis, Lomandra (33 
species) and Xanthorrhoea (12 species). Staff (in Stevens 1978) described the leaf 
anatomy of Romnalda papnana. Detailed descriptions are therefore not given here, 
but taxonomically significant characters are presented (Table 5). 
Leaf surface Surface waxes are generally present but not oriented in parallel lines or 
long wax ribbons in any of the genera. 
Branched hairs occur on the leaf of Calectasia (Fig. 3c), especially at the margins, and 
in Dasypogon large multicellular epidermal structures are present at the leaf margins, 
sometimes extending into branched hairs. Baxteria and Kingia apparently lack hairs on 
most of the leaf, although long multicellular hairs are present at the leaf bases in 
Kingia. Unbranched unicellular hairs (papillae) are present surrounding stomata in 
Xerolirion and also in species of Acanthocarpus, Chamaexeros, Lomandra and Xanthorrhoea. 
Acanthocarpus, Chamaexeros, Lomandra and Xerolirion (Fig. 4c) have anomocytic stomata 
and elongated epidermal cells (typical of Asparagales), although in Lomandra 
(Tomlinson 1974) paracytic or tetracytic types are sometimes present, formed by 
oblique cell divisions. In Lomandra preisii a typical agenous ontogeny was observed 
(Fig. la), which leads after cell elongation to the anomocytic type, although sometimes 
with oblique end walls. Baxteria, Kingia (Fig. 3a) and Xanthorrhoea have paracytic/ 
tetracytic stomata; Tomlinson (1974) recorded oblique cell divisions in Xanthorrhoea, 
but Baxteria and Kingia are still unknown in this respect. Calectasia and Dasypogon 
closely resemble each other in that all mature epidermal cells are short and polyhedral 
or irregular in shape, with several cells surrounding the stomata. In Dasypogon 
bromeliifolius both mesogene and perigene cells were observed, and both oblique and 
non-oblique divisions in cells adjacent to the meristemoid (Fig. lb,c). 
Leaf TS Superficially, leaf structure in cross sections of Kingia australis and 
Xanthorrhoea australis is remarkably similar (Fig. 2d, f), mirroring the strong similarity 
of these two genera in vegetative morphology. Both have quadrangular leaves, 
modified substomatal cells and phloem in two distinct strands in each vascular 
bundle, and also more taxonomically widespread characters such as raphides absent 
and stomata tetracytic. Both have an outermost chlorenchymatous region, of 2-3 
