2. Ophioglossum L. (adder's tongue)
Vegetative portion of the leaf simple, sessile or short-stalked, lanceolate to
ovate in outline, the base wedge-shaped to cordate, sheathing the stalk of the
fertile spike, the veins branched, copiously anastomosing. Fertile portion of
the leaf an erect, long-stalked spike, the sporangia sunken into the axis of
the spike, in 2 rows on opposite sides. Twenty-five to 30 species, nearly
worldwide.
The
species of Ophioglossum are probably more widespread in Missouri than present
records indicate, as the plants are relatively inconspicuous and the leaves are
only visible for a few months each year. The genus contains the highest
chromosome numbers of the vascular plants (see O. vulgatum, below).