midvein

The male fern resembles the marginal shield fern in outline, but the fronds are thinner, are not evergreen, and the sori are near the midvein.

The Fern Lover's Companion A Guide for the Northeastern States and Canada George Henry Tilton

Fruit-dots large, round, half way between the midvein and the margin.

The Fern Lover's Companion A Guide for the Northeastern States and Canada George Henry Tilton

Sori linear, a row on either side of the midvein, and at right angles to it, the indusium appearing to be double.

The Fern Lover's Companion A Guide for the Northeastern States and Canada George Henry Tilton

The main rib or vein of a segment, pinnule, pinna, or frond; a midvein.

The Fern Lover's Companion A Guide for the Northeastern States and Canada George Henry Tilton

A frond is bipinnate (Latin, _bis_, twice) when the lobes of the pinnæ extend to the midvein as in the royal fern (Fig. 2).

The Fern Lover's Companion A Guide for the Northeastern States and Canada George Henry Tilton

Sori in rows each side of the midvein, one to each tooth and often scattering on the lower pinules.

The Fern Lover's Companion A Guide for the Northeastern States and Canada George Henry Tilton

Sori numerous, rather near the midvein, stipe and rachis lustrous brown.

The Fern Lover's Companion A Guide for the Northeastern States and Canada George Henry Tilton

Fruit-dots near the midvein, the sides of the sinus often overlapping.

The Fern Lover's Companion A Guide for the Northeastern States and Canada George Henry Tilton

In a bipinnate frond one of the smaller divisions extending to the secondary midvein.

The Fern Lover's Companion A Guide for the Northeastern States and Canada George Henry Tilton

A frond is pinnátifid when its lobes extend halfway or more to the rachis or midvein as in the middle lobes of the pinnátifid spleenwort (Fig. 3).

The Fern Lover's Companion A Guide for the Northeastern States and Canada George Henry Tilton