Fig. 278.
Elaters, at left
showing the two
spiral marks, at
right a branched
elater.
Figs. 275-278.—Sporogonium of liverwort (jungermannia) opening by splitting into four parts,
showing details of elaters and spores.
[The Horned Liverworts.][25]
501. The horned liverworts take their name from the shape of the sporogonium. This is long, slender, cylindrical, pointed, and very slightly curved, suggesting the shape of a minute horn. Anthoceros is one of the most common and widely distributed species. The plant grows on damp soil or on mud.
Anthoceros.
502. The gametophyte.—The gametophyte is thalloid. It is thin, flattened, green, irregularly ribbon-shaped and branched. It lies on the soil and is more or less crisped or wavy, or curled, the edges nearly plane, or somewhat irregular, and with minute lobes, or notches, especially near the growing end. The general form and branching can be seen in [fig. 279]. Where the plants are much crowded the thallus is more irregular, and often possesses numerous small lateral branches in addition to the main lobes. Upon the under side are the slender rhizoids, which attach to the soil. With a hand lens there can be seen also upon the under side small dark, rounded and thickened spots, where an alga (nostoc) is located.
Sexual Organs of Anthoceros.
502. The sexual organs of anthoceros differ considerably from those of the other liverworts studied. In the first place they are immersed in the true tissue of the thallus, i.e., they do not project above the surface.
