Chapter 1: The Characeae Plant

6
1.2.1 The Chara corallina/australis group of species
The species in this group have a relatively simple morphology compared to most other
species of Chara (which are illustrated in Figs 1-5). The internodes and branchlets are
without a cortex (ecorticate or naked), which allows direct manipulation of the giant cells that
make up the internodes (Fig. 1.6a). The gametangia occur either together (oogonium above
the antheridium in Chara corallina Kl. ex Willd.) or on separate plants (in the dioecious
Chara australis R. Br.), so sometimes two plants (male and female) are needed for sexual
reproduction to take place (Fig. 1.6b, c). The absence of a cortex coincides with a lack of
spine cells. There is one row of stipulodes beneath the branchlets (Fig. 1.6f), and this is
usually poorly developed (Fig. 1.6g). Bract cells and bracteoles are reduced in comparison
with many species (Fig. 1.6e). Chara corallina and C. australis were amalgamated in the past
(Wood 1962; 1965; 1972), and the two species are distinguished primarily on the basis of
sexuality (i.e. C. corallina is monoecious (both male and female organs occur on the one
plant) and C. australis is dioecious (separate male and female plants)). Oogonia and
antheridia occur on the branchlets as well as inside the base of the branchlet whorl (Fig. 1.6a,
b, c).
The taxonomy of this group has been problematic and over time (see section Charophyte
names) and members of this group have been variously placed in the genera Tolypellopsis,
Protochara, Chara and Nitella (Table 1. Wood 1972). Recent morphological (e.g. Casanova
2005) and genetic analysis indicates that Chara australis from Australia and New Zealand,
and Chara corallina from south-east Asia, should be retained as separate species, and that
Chara lucida A. Braun (a very thin species with short internodes from tropical northern
Australia) and Chara stuartiana Kütz. (a very robust species from Tasmania) can also be
distinguished. The Asian species Chara wallichii A. Braun (India) and C. fulgens Filarszky
(Indonesia) have also been described and these differ from C. australis and C. corallina in
the arrangement of the reproductive structures and expression of bract cells (Zaneveld 1940).
1.2.2 The Lamprothamnium papulosum/macropogon group of species
Lamprothamium papulosum (Wallr.) J. Groves was the first species to be described in this
group. It was originally placed in the genus Chara and later transferred to the genus
Lychnothamnus. Later, when it was found to be different from the other species of
Lychnothamnus it was placed in a genus on its own (Lamprothamnus), which was renamed