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Nuytsia Vol. 7, No.2 (1990) 
Affinities Trianthema kimberleyi is closely related to T. compacta, T. glossostigma, and 
1. oxycalyptra. It is distinguishable from these species by the ± valvate (instead of imbricate) 
tepals. Additionally, it dilters from T. compacta by the mucronatc, more succulent, always petiolatc 
leaves, the constant number and regular arrangement of the stamens, and the aril, which does not 
swell alter moistening in T. compacta\ from T. glossostigma by the stamen number and the 
unsculptured tesla (ribbed in 7 . glossostigma ); from T. oxycalyptra by the absence of the dorsal 
unuacial mucro on die tepals, and the smooth aril, which is conspicuously papillate in 
7 . oxycalyptra. 
Etymology . The specific epithet refers to the distribution of the species, which is known at present 
only from the type locality in the southern Kimberley region of Western Australia. 
Trianthema triquetra Willd. 
I rianthema triquetra belongs to a group of species with its centre of distribution in the arid 
regions of southwest Africa, east Africa and India. As mentioned above, the species of this group 
belong to the subgen. Papularia (Forsk.) Jeffrey (characterized by two superposed ovules and 
usually clustered flowers), but up to now has not been assigned formal taxonomic rank, and still 
awaits critical revision. Differences between species described in the published Floras of the areas 
H^tioned olten are restricted to form and size of leaves, tepals and the perianth tube, characters 
which are subject to some plasticity dependent on water supply. Some taxa (species, subspecies or 
varieties), however, seem to be well circumscribed, but an investigation of the group over its whole 
distribution is necessary, before a satisfactory classification is possible. 
The members of this group are characterized by smooth or papillose leaves and stems; and 
two-seeded circumscissile capsules, the circular operculae of which are depressed at the apex and 
partially enclose the upper seed. The dead tepals are generally hygrochastic and, when bending 
outwards after wetting, loosen the operculae which are then washed away by raindrops, thus 
lunctioning as dissemination units. The small, often inconspicuous flowers have only five stamens 
alternate to the perigon lobes. Also, form and sculpturing of the seeds are rather similar in all 
members of the group. 
7 rianthema triquetra contains two subspecies described from Africa and a number of varieties. 
In the treatment for volume 4 ot the Flora of Australia ", Prescott (1984) describes two varieties 
only. Apparently it was assumed that only T. triquetra subsp. triquetra occurs in Australia as no 
other subspecies arc mentioned. Prescott (1984) notes considerable confusion in the use ’of the 
names of the two varieties (T. triquetra var. triquetra and T. triquetra var. clavata (J. Black) 
H. Eichlcr), which are mainly delimited by the different leaf form and degree of succulence. 
According to her, the variety with clavate, more succulent leaves is restricted to central Australia 
and may only be a modification under extreme arid conditions. Such different forms, however, can 
also be found in northwest Australia, sometimes even occurring sympatrically (Figure 2). It’ was 
found in comparative cultivation that the different leal' forms are genetically fixed. 
In Australia there occurs, however, a third lorm, which seems to be far less common than the 
former two and has been overlooked hitherto. The new form was recently collected by us in 
northwest Australia {Bittrich & Jenssen 18601, 18616, 18646; HBG, PERTH). The difference 
between the new form and the two other varieties lies in the leaf anatomy, which can be easily 
recognized in living plants, but only with difficulty in herbarium specimens. The varieties 
rrianthema triquetra var. triquetra and var. clavata develop a water-storing tissue adjoining the 
epidermis on the abaxial side of the leaf (Figures 2 & 3). Therefore, the chlorcnchymc is developed 
on the adaxial side of the leaves only or in more succulent leaves (hence the varietal epithet 
clavata") where it forms a semicircle around the water tissue. The leaves of the new form 
however, show a central water-storing tissue only and have a chlorcnchyme on both sides, thus 
being isobilateral in cross-section (Figure 3). In some leaves a very small gap in the chlorcnchyme 
edn be found on the abaxial side, visible ns a narrow translucent band which either stretches from 
the base to the top of the leaf or is present only in the basal part. This is reminiscent of the strongly 
