Fig. 220.—Marsilia salvatrix: A the sporocarp commencing to germinate; B a more advanced stage of germination.
Fig. 221.—Pilularia globulifera (natural size): s sporocarps; b leaves; k the growing point; r roots.
Marsilia quadrifolia, in Europe. Many species are found in Australia. The nutritious sporocarps of M. salvatrix were the means of saving the Burke expedition in the interior of Australia, and hence this species has earned its specific name.
Pilularia has linear leaves, without lamina. The sporocarps are spheroid (Fig. [221]), brown and hard, and situated near the base of the leaves. They are 2–4 chambered and open by a corresponding number of valves.
Class 2. Equisetinæ (Horsetails.)
The characteristics of this class have been described on page [204].
It is divided into two sub-classes:—
1. The isosporous Equisetinæ. To this sub-class belong, with certainty, only the Equisetaceæ now existent, which are represented by only one genus, Equisetum.