Schizaeales

Order Schizaeales

Ecology & Form

  • All members of the Schizaeales have dimorphic fertile and sterile fronds and lack well-defined sori

  • Their sporangia have a horizontal annulus that lies below and completely encircles the top of the sporangium

Classification

└Tracheophytes

└Euphyllophytes

└Ferns (Polypodiopsida)

└Polypodiidae

└Schizaeales

Diversity

  • 3 families (Anemiaceae, Lygodiaceae, and Schizaeaceae)

Anemiaceae

  • 1 genus (Anemia); 119 species

  • Ferns with compound frons and are typically terrestrial or growing on rocks (epipetric)

Stems

  • Stems compact or short-creeping, horizontal, solenostelic (having phloem on both sides of xylem) or dictyostelic (having complex nets of xylem), clothed with orange to reddish-brown hairs

Leaves

  • Leaves erect (rarely forming a flat rosette), partially to entirely dimorphic

Reproductive features

  • Sporangia in 2 rows on ultimate segments of fertile pinnae, sessile, oblong; annulus apical

  • Spores tetrahedral-globose, with parallel or rarely anastomosing ridges

Gametophyte

  • Gametophytes terrestrial, green, cordate with unequal lobes

Above: Anemia mexicana

Lygodiaceae

  • 1 genus (Lygodium); 40 species mostly tropical; a few temperate

  • Lygodium is a climbing fern, with a distinctive growth habit

  • The rachis of the frond is long and flexible, with indeterminate growth, so that the fronds form climbing or trailing vines

  • Cretaceous - present

Stems

  • Stems subterranean, protostelic

  • Indument of dark, dense hairs.

Leaves

  • Leaves vinelike, of indeterminate growth. Pinnae reduced to short stalks, each bearing a pair of opposite pinnules, usually with an often dormant apical bud.

Reproductive features

  • Sporangia in 2 rows, 1 on each side of midvein of contracted, oblong, marginal lobes of ultimate segments, covered by hood-like flap of tissue serving as indusium

  • Spores tetrahedral-globose, trilete, rarely monolete

Gametophyte

  • Gametophytes terrestrial, cordate, glabrous

Above: Lygodium japonicum

Schizaeaceae

  • 2 genera (Actinostachys and Schizaea); 38 species

  • Small ferns with forking fronds and a distinctive, grass-like appearance

  • Tropical Old and New World, parts of the Eastern USA, Chile, the Falkland Islands, and various Pacific islands, including several islands of New Caledonia, as well as Australia and New Zealand; In Africa at least two species are endemic to South Africa

  • Late Cretaceous - present

Stems

  • Stems mainly erect, covered with many stiff hairs 1--3 cells long, with simple siphonostele (hollow vascular cylinder)

Leaves

  • Vegetative fronds (trophophylls) are grass-like

  • Leaves tufted, monomorphic or dimorphic

  • Petioles much longer than blades, blades reduced to tiny apical fistlike or radiating groups of rudimentary fertile pinnae ("digits")

  • Petioles are sometimes repeatedly dichotomous, in some species webbed between branches to form fan-shaped false blades

  • Fertile fronds (sporophyll) are similar, but with a small, pinnate fertile segment at its apex

    • The upper surface of the pinnules bear the sessile capsules

Reproductive features

  • Sporangia arranged in 1--4 ranks on abaxial surface of digits with revolute margins

  • Annulus subapical, composed of 1--(2--3) layer(s) of thickened cells

Gametophyte

  • Gametophytes subterranean and not green or borne aboveground and green, tuberlike or flattened, cordate or filamentous. Spores bilateral, monolete.

Above: Schizaea pectinata showing crozier, fertile fronds, and grass-like barren fronds

Below: Actinostachys pennula