. Elementary botany. Botany. There is so much moisture in these little pockets of the under side of the leaf that minute animals have found them good places to live in, and one frequently discovers them in this retreat. There is here also a third row of poorly developed leaves on the under side of the stem. 330. Porella.—Growing in similar situations is the plant known as porella. Sometimes there are a few plants in a group, and at other times large mats occur on the bark of a trunk. This pla t porella, also has closely overlappmg leaves in rows on opposite sides of the stem and the lower marg
. Elementary botany. Botany. There is so much moisture in these little pockets of the under side of the leaf that minute animals have found them good places to live in, and one frequently discovers them in this retreat. There is here also a third row of poorly developed leaves on the under side of the stem. 330. Porella.—Growing in similar situations is the plant known as porella. Sometimes there are a few plants in a group, and at other times large mats occur on the bark of a trunk. This pla t porella, also has closely overlappmg leaves in rows on opposite sides of the stem and the lower margin of each leaf is curved under somewhat as in frullania, though the pocket is not so well formed. The larger plants are female, that is they bear archego- nia, while the male plants, those which bear antheridia, are smaller and the an- theridia are borne on small lateral branches. The an- theridia are borne in the axils of the leaves. Others of the leafy-stemmed liverworts live in damp situations. Some of these, as Cephalozia, grow on damp rotten logs. Cephalozia is much more delicate, and the leaves are farther apart. It could not live in such dry situations where the frullania is sometimes found. If possible the two plants should be compared in order to see the adaptation in the structure and form to their environment. 331. Sporogonium of a foliose liverwort.—The sporogonium of the leafy-stemmed liverworts is well represented by that of several genera. We may take for this study the one illustrated. Thallus of a thalloid liverwort (blasia) showing lobed margin of the frond, intermediate between thalloid and foliose Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Atkinson, George Francis, 1854-1918. New York, H. Holt
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