(Adder's tongue family)

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GENERA (3) include Botrychium, Ophioglossum, and Helminthostachys.

THE OPHIOGLOSSACEAE are an isolated family, not closely allied to other living family of ferns. They have been aligned with a progymnosperm lineage. The family shows some primitive characters, such as large, massive sporangia with high spore capacity. The Ophioglossaceae have a high colonizing capacity, and commonly occur in recently glaciated or climatically altered regions.

SPORANGIA are sessile or subsessile. They are borne on special branches, that arise from the bases of fertile leaves or below sterile ones. They are separate, or laterally joined in a synangium, and lack an annulus.

SPORES are homosporous, and lack chlorophyll. They are consistently trilete, and have one of the most elaborate sporoderm structures in the Filicopsida.

STEMS range from erect and unbranched, to prostrate and rarely branched. They are small and fleshy, and may be pubescent-scaly at the apex.

PETIOLES are continuous with the stalk of the sporophore. Enlarged at the base into a membranous, stipular sheath, they each at least partially enclose a bud.

LEAVES are small, usually only a few cm in length (rarely 50 cm long). Entire, pinnate, or broadly and deeply palmate, they are rarely circinate in bud. Leaves are glabrous or thinly pubescent. Sterile leaf blades may be expanded, or reduced/absent (Ophioglossum simplex).

VENATION is branching. The vascular cylinder may be siphonostelic, or (rarely) dictyostelic.

THE GAMETOPHYTE is mycorrhizic, subterranean, and non-photosynthetic. Fleshy and irregularly elongate, it may be branched or nearly spherical. Antheridia and archegonia are rather uniformly distributed, or dorsiventral with the gametangia on the upper surface.

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