CHAPTER XI. MOSSES, MUSHROOMS, AND MOULDS.

40. LIVERWORTS AND TRUE MOSSES.

1. =A common liverwort.=—Look along the sides of a brook or a well, and try to find a flat green plant with numerous lobed and overlapping branches. Each branch is perhaps half an inch across. This is one of the commonest liverworts (_Pellia_). Notice the prominent midrib running along each branch. In spring, observe the “frilled” appearance of the end, caused by the small new branches.

Pull the plant up, and notice that it is attached to the soil by a large number of fine _hairs_ which spring from the lower surface of the midrib.

In February, or March, examine the upper surface of the growing plant with a lens, and notice the small, dark-green balls, mounted on short, thick stalks. Examine these at intervals until May, and notice that the stalks then grow rapidly until they are two or three inches long. Each is white, and still bears the black ball (the _capsule_) on its summit. When the stalk is full-grown, the capsule opens—its wall splitting into four parts—to liberate the _spores_. How soon, after the liberation of the spores, do the capsule and its stalk die down?

2. =A common moss.=—Separate a single plant from a tuft of the common moss (_Funaria_) which grows, almost everywhere, on the ground and on walls. Notice that the plant consists of a _stem_ perhaps half an inch high, thickly covered with small simple green _leaves_. The moss is fixed in the soil by a tuft of fine _hairs_.

On some of the plants notice a thin stalk (about half an inch long) springing from the top of the stem; and on the end of the stalk an ovoid _capsule_ or spore-box. In cases where the stalk is not yet full-grown, notice that the capsule is covered by a conical _hood_, somewhat like a candle-extinguisher.

Select a plant bearing a ripe capsule, and warm it gently before the fire—holding it over a sheet of paper—to dry it. Examine the mouth of the capsule with a lens, and try to see the teeth which surround the opening. Then shake the capsule over moist soil in a small flower-pot to scatter the _spores_; cover with a sheet of glass and keep in a warm room. In a few days notice that the soil is covered with fine green threads. Ultimately new moss plants will grow from these.

=The life-history of a liverwort.=—One of the commonest and simplest of this class of plants is known to botanists as _Pellia_. It may generally be found growing by the sides of streams or old wells. It has neither stem, leaves, nor root, but consists of flat, green, overlapping lobes which fork at their ends. It branches very freely, and in spring the new branches give the ends of the lobes a frilled appearance. A rather prominent midrib runs along each branch. The plant is attached to the soil by a large number of fine hairs which spring from the lower surface of the midrib.

The whole appearance of this liverwort is very suggestive of the prothallus (Fig. 147) of a fern; and, indeed, it corresponds to a prothallus, not only in its general structure and mode of life, but also in bearing sexual organs of a very similar type. It was seen in