OsmundaceaeOsmundaceae
GENERA (3) include Osmunda. Todea, and Leptopteris .
THE OSMUNDACEAE show some primitive features, including a rudimentary annulus, and stipular leaf bases. They lack sori.
SPORANGIA all mature at once, and are bivalvate. They are borne separately, or in clusters on short leaf segments. Large and pear-shaped, each sporangium has a short, stout stalk and walls 2 cells thick. The annulus is poorly developed.
SPORES are homosporous, and photosynthetic. They occur in groups of 256-512. The spores are trilete, and the echinae of the perispore bear unique tubercles.
STEMS may be erect or decumbent. They are massive and indurated. Usually dichotomously branched, stems may have a single arborescent trunk.
PETIOLES are long, with stipule-like wings at the base.
LEAVES are pinnate, ca. 1-2 m long. They bear trichomes, at least when young. Leaves may be sterile or fertile, or divided into fertile and sterile parts.
THE VASCULAR CYLINDER is medullated protostelic, becoming dictyostelic.
RHIZOMES are stout and sclerenchymatous. They are covered with persistent leaf bases and fibrous roots, but lack scales.
THE GAMETOPHYTE is
epigeal, and photosynthetic. Terrestrial and fleshy, it is obcordate
to elongate, and centrally thickened. Archegonia are borne on
the lower surface in rows along both sides of the thickened center.
Antheridia are mostly borne on the lower surface of the margins,
less often at their edge.
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