. Lessons in botany. Botany. QUILLWORTS. I8l leaf to a quill. Fig. 155 represents one of these quillworts (Isoetes engelmannii). The leaves are the prominent part of the plant, and they are about all that can be seen except the roots, without removing the leaves. Each leaf, it will be seen, is long and needle-like, except the basal part, which is expanded, not very unlike, in outline, a scale of an onion. These expanded basal portions of the leaves closely overlap each other, and the very short stem is completely covered at all times. Fig. 157 is from a longitudinal section of a quill- wort. I
. Lessons in botany. Botany. QUILLWORTS. I8l leaf to a quill. Fig. 155 represents one of these quillworts (Isoetes engelmannii). The leaves are the prominent part of the plant, and they are about all that can be seen except the roots, without removing the leaves. Each leaf, it will be seen, is long and needle-like, except the basal part, which is expanded, not very unlike, in outline, a scale of an onion. These expanded basal portions of the leaves closely overlap each other, and the very short stem is completely covered at all times. Fig. 157 is from a longitudinal section of a quill- wort. It shows the form of the leaves from this view (side view), and also the general outline of the short stem, which is tri- angular. The stem is therefore a very short object. 297. Sporangia of isoetes.— If we pull off some of the leaves of the plant we see that they are somewhat spoon-shaped as in fig. 156. In the inner surface of the expanded base we note a circular depression which seems to be of a different texture from the other portions of the leaf. This is a sporangium. Beside the spores on the inside of the sporangium, there are strands of sterile tissue which extend across the cavity. This is peculiar to isoetes of all the members of the class of plants to which the ferns belong, but it will be re-. Fig. 155- Isoetes, mature 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 and company
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