. How to know the ferns; a guide to the names, haunts and habits of our common ferns. Ferns. EXPLANATION OF TERMS. Fig. 4 A frond is once-pinnate when the incisions extend to the midvein (Fig. 3). Under these conditions the midvein is called the rachis («), and the divisions are called the pinncB (b). A frond is twice-pin- nate when the pinn^ are cut into divisions which extend to their midveins (Fig. 4). These divisions of the pinnse are called pin- nules {a). A frond that is only once-pinnate may seem at glance twice-pinnate, as its pinnze may be so deeply lobed or pinnatifid as to req
. How to know the ferns; a guide to the names, haunts and habits of our common ferns. Ferns. EXPLANATION OF TERMS. Fig. 4 A frond is once-pinnate when the incisions extend to the midvein (Fig. 3). Under these conditions the midvein is called the rachis («), and the divisions are called the pinncB (b). A frond is twice-pin- nate when the pinn^ are cut into divisions which extend to their midveins (Fig. 4). These divisions of the pinnse are called pin- nules {a). A frond that is only once-pinnate may seem at glance twice-pinnate, as its pinnze may be so deeply lobed or pinnatifid as to require a close examination to convince us that the lobes come short of the midvein of the pinna^. In a popular hand-book it is not thought necessary to explain further modifications. The veins of a fern are free when, Fig. 5 branching from the midvein, they do not unite with other veins (Fig. 5). Ferns produce spores (Fig. 6) instead of seeds. These spores are collected in spore- cases or sporangia (Fig. 7). Usually the sporangia are clustered in dots or lines on the back of a frond or along its margins. These patches of sporangia are called sari or fruit- 3P Fig. 6. 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 Parsons, Frances Theodora, 1861-1952. New York, C. Scribner's Sons
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