Fig. 135. Part of a Bladder-wrack, showing the floats (f) and special swollen tips (s).
The seaweeds have the most complicated way of forming spores of any of this family. There are special little swellings at the ends of the plant, as in the ordinary bladder-wrack, for example (fig. 135 (s)), and in these are formed the cells which will give rise to new plants. The other simple bladders (fig. 135 (f)) are only full of air, and act as floats to keep the plant up in the water.
In this the simplest family of all, we find more variety in the appearance of its members than in any of the others, so that it may seem to be rather difficult to recognise the plants which belong to it. Perhaps the easiest way of settling this, is to see if the plant fits into any of the other families, and if it never has flowers nor cones, neither fern spore-capsules nor the big spore-capsules of the moss family, then you are fairly safe in classing it with the simplest plants.
Very many of the plants of this family are found living in water, which is perhaps one of the reasons that they can afford to be so simple, because the water protects them from many of the dangers land-plants have to prepare against, such as wind, drought, or too much sunshine. This is the simplest family of real, undoubted plants; but there is one class still simpler, and that is the family of bacteria, about which you must have heard much, as many of them cause our diseases, though others do much valuable work for us. All the same, we will leave these little creatures alone, and content ourselves with the five great families of plants which we can see with our own eyes.
PLATE IV.
A LOW EDGE OVERGROWN WITH FOXGLOVES AND MANY OTHER WILD PLANTS