TH E TASMANIAN NATU KALIS’T. 
69 
Dotes on plant Classification 
By L. RODWAY (Government Botanist). 
II. KERNS. 
SI^*HE common way in which a fern is often recognised is by observing 
41 that its leaves are relatively large and often much divided. It is 
not at all unusual to find people calling the deadly hemlock a fern and 
growing it in a garden, simply because it looks like one. This is an 
unfortunate mistake, and sometimes results in the death of a cow, 
which is inconvenient. Kor this reason alone, it is well to know what 
really is a fern. Besides, a naturalist should have some better reason 
for saying what is a fern, and what not, than general resemblance. 
We should note, firstly, that a fern never bears flowers and fruit. 
If a plant looking like a fern develops flowers, it belongs to the group of 
flowering plants and not to the ferns. This brings us to an important 
detail. Plants may vary extraordinarily in general appearance, but their 
method of producing is very constant. Each natural group has its own 
method, and by it we know them. The result of profound study and 
research for many generations has led to this conclusion—that if we 
wish to group plants according to their true relationship, we must over¬ 
look general appearance, and pay attention to their modes of repro¬ 
duction. 
If you examine the leaves of a fern you will find — at least upon 
some of them, situated upon the back, or close to the margin, or in 
others in little pockets — brown markings, which can readily be seen to 
be of a powdery nature. If some of this powder be removed and 
examined by the aid of a strong lens, or better still, under a micro¬ 
scope, it will be found to consist of beautiful little bags, each one full of 
spores. These bags are called sporangia, and it is as well to remember 
this name, for its use will be very necessary in our papers on other 
groups of plants. Well, a fern is a plant that bears numerous sporangia 
upon relatively large leaves. Because ferns bear sporangia upon their 
leaves, it was once considered that these organs were something more 
than leaves, and they were called fronds. This is now pretty generally 
abandoned, and the name frond is only used lor bodies which may be 
leaflike but are not leaves, as, for instance, the expansions of many 
seaweeds. 
When these sporangia are ripe, and weather conditions are favorable, 
they burst and scatter their spores. These bodies being very small are 
carried often to some distance by currents of air. Now comes an 
important feature in the life-history of a fern. When a spore finds itself 
in suitable conditions it germinates, but instead of growing into a fern 
like the one from which it arrived, it assumes a different state altogether. 
It grows into a little flat green plate, generally heart shaped, and seldom 
a quarter of an inch long. This it would be most unwise to call a fern ; 
it has received the name of a prothallium. In any conservatory where 
ferns grow these little prothallia may be found in quantity on damp 
