The Manual of the Botany of the Northern United States / Including the District East of the Mississippi and North of North Carolina and Tennessee

by Asa Gray

[*][*][*] Indusium obscure, irregularly semicircular. Fertile fronds much contracted and very unlike the sterile ones.

15. Onoclea. Sporangia on an elevated receptacle; divisions of the fertile frond pod-like or berry-like.

Tribe VII. WOODSIEÆ. Sori round, borne on the veins; indusium fixed under the sorus, divided into segments or into slender filaments.

16. Woodsia. Small ferns with free veins. Indusium very delicate.

Tribe VIII. DICKSONIEÆ. Sori roundish, marginal or submarginal. Indusium cup-shaped or two-valved, the outer portion composed of a reflexed lobule of the frond, or more or less united to it.

17. Dicksonia. Indusium in our species small, membranaceous, nearly globular. Frond elongated, decompound.

Suborder II. Hymenophyllàceæ. Sporangia sessile on a bristle-like receptacle within a cup-shaped or bivalvular involucre, the ring transverse and complete. Fronds delicately membranaceous.

18. Trichomanes. Involucres funnel-form or cup-shaped.

Suborder III. Schizæàceæ. Sporangia ovate, sessile, having a complete transverse articulated ring at the apex, and opening by a longitudinal slit. ([Pl. 19.])

19. Schizæa. Sporangia naked, fixed in a double row to the midrib of the narrow fertile segments. Sterile fronds rigid, simple or dichotomously branched.