Briggs and Johnson, Hopkinsiaceae and Lyginiaceae 
493 
tenax Labill. was based on specimens of two species. Brown selected the male 
specimen as lectotype, basing Leptocarpus tenax (Labill.) R. Br. on it, while referring the 
female syntype to Lyginia imberbis R. Br. Lyginia is no longer included among the 
nomina conservanda genericorum, although it retains a conserved type.) 
Description and distribution: as for the family. 
Species within Lyginia have proved difficult to delimit, so that the names L. barbata and 
L. imberbis have been defined variously, or the whole genus considered to be only a 
single species. A major clarification came with the studies of Bell and Pate (1993) who 
investigated the reproduction and regeneration of plants and distinguished five 
morphotypes. These were characterised by differences in rhizome morphology, culm 
height and density, spikelet morphology, response to fire, timing of first reproduction 
in juveniles, and seed/ovule numbers and ratios. The species now recognised equate 
to these units, as characterised by Bell and Pate, as follows: 
L. excelsa sp. nov. = morphotype S: 'tall-culmed, densely tufted fire-sensitive 
obligate seeder'. 
L. imberbis R. Br. = morphotypes R] 'tall densely tufted fire-resistant resprouter'; R 2 : 
'short flexuose-culmed, tufted resprouter'; and R 3 : 'weakly clonal, semi-tufted 
resprouter'. 
L. barbata R. Br. = morphotype Ry 'short-culmed, widely spreading clonal form'. 
We have concluded that there is no basis for specific distinctions between 
morphotypes R,, R 2 and R 3 . L. imberbis, as now recognised, is by far the most variable 
and abundant of the species. It includes considerable local variation; for example, 
plants from different sites often show consistent differences in culm height and 
sinuosity, corresponding to three of the morphotypes distinguished by Bell and Pate 
(1993). L. barbata shows an almost equally wide geographic distribution but is 
restricted to a much narrower habitat range, whereas L. excelsa is known from only a 
very few sites. Bell and Pate found differences between the morphotypes now 
included in L. imberbis in seed/ovule ratios and resource allocation to reproduction, 
but by far the largest differences in these variables correspond to the specific 
distinctions now recognised. They noted the clear demarcation between the groups 
now specifically distinguished, regarding Rj, R 2 and R 3 as together forming 'an 
intermediate grouping of resprouter forms', distinct from the obligate seeder and 
extensive clonal types. 
The species occur sympatrically or in close proximity without evidence of 
intergradation (Bell & Pate 1993). L. excelsa occurs with L. barbata at Cataby. L. imberbis 
and L. barbata are found together at various localities but are more often parapatric 
since L. barbata is generally on more sandy and better drained sites. There is little 
difficulty in identifying most collections that adequately sample the base of the plant. 
Especially in the Eyre region, however, some plants are difficult to determine since L. 
imberbis shows considerable variation in the denseness of the tussocks, the extent to 
which culms are supported by short but distinct rhizomes, and in the development of 
cilia. Elongated rhizomes are a reliable characteristic of L. barbata, although these do 
not develop until about the fifth year of growth from seed (Bell & Pate 1993). Since 
establishment from seed is infrequent in this strongly clonal species, juvenile plants 
that would be difficult to identify are correspondingly rarely encountered (Pate 2000). 
