OF SOUTH AUSTRALIA. 
33 
Bryopsis plumosa (Hudson) C. Agardh. 
Fronds erect, naked below, simple or decompound pinnate above, 
forming elegant green plumes. There is no creeping surculus as in 
Caulerpa. The fronds are of a transparent green, glossy and shining, 
and there are no divisions into cells. 
Growing on rocks about low-water mark, but also extending to no great 
depth of water. 
Family CAULERPACEAE. 
CAULERPA Lamouroux. 
The genus Caulerpa (creeping stem) founded by Lamouroux in 1800, 
and as yet not merged or broken up into a number of smaller independent 
genera, is probably the most remarkable type in the vegetative kingdom. 
The plants of the genus are characterised by possessing a long, 
cylindrical, creeping stem, the surculus, which sends downwards bunches 
of fine, branching, colourless fibres, the rhizoids, by means of which it 
attaches itself to the rocks or sand among which it creeps, and sends 
upwards green fronds, the assimilators, of the most varied form. The 
fronds of the smallest species are an inch or less high while those of the 
largest are over a foot in length, but, small or great, each plant is formed 
out of a single cell, the branchings of which constitute the rhizoids and 
the assimilators. There are no cross walls, and there is no aggregation 
of the protoplasmic matter into distinct small bodies. The firmness of 
stem and frond is secured by a system of narrow beams, trabeculae, which 
pass from wall to wall of the long cell, and are composed of a substance 
very like but apparently differing from cellulose. 
The surculus, itself, like a strawberry runner, is of apparently indefinite 
length and growth, and usually gives off similar branches, which go on 
growing, and, if accidentally or naturally severed, still continue to give 
off fresh rhizoids and assimilators of now independent plants. As at 
present certainly known, this is the only way in which new plants are 
formed. The surculus is cylindrical, green where exposed to light, and 
may be quite smooth or beclothed with small scales, according to the 
species. It is slender in some species, but may have a diameter of a Jin. 
in others. 
It is the fronds of Caulerpa which are most remarkable. Nature seems 
to have shown what a variety of forms she can produce out of one single 
undivided cell, just as the one-celled Foraminifera foreshadow the designs 
and patterns of the Mollusca. Thus we have prototypes, as it were, of 
Charas, Mosses, Ferns, Horsetails, Clubmosses, Cypresses and Araucarias, 
Stonecrops, Cacti and Phanerogams with broad simple leaves. So marked 
is this diversification of type that all botanists accept J. G. Agardh ’s 
classification of the genus in sections according to the likeness to the 
various classes of the more elaborated groups. 
B 
