Gleicheniales

Order Gleicheniales


Ecology & Form

  • These ferns are characterized by root steles having 3–5 protoxylem poles

  • Antheridia with 6–12 narrow, twisted, or curved cells in their walls

  • Their habitats are highly diverse, including plants with the typical fern fronds, others whose leaves resemble those of palm trees, and yet others again which have undivided leaves

  • They are tropical ferns, most diverse in Asia and the Pacific region.

Geologic Range

  • Triassic - present

Diversity

  • 3 families (Dipteridaceae, Gleicheniaceae, and Matoniaceae)

  • 10 extant genera (see families below)

  • ~174 extant species


Dipteridaceae

  • Known as the umbrella ferns

  • 2 extant genera (Cheiropleuria, Dipteris); ~10 extant species

  • The group is confined to Asia, New Guinea, and northern Australia

  • Middle Triassic of Italy, Australia, and Argentina

  • 7 extinct genera (Hausmannia, Clathropteris, Dictyophyllum, Thaumatopteris, Camptopteris, and Polyphacelus)

Above: Dipteris conjugata

Gleicheniaceae

  • 6 genera (Dicranopteris, Diplopterygium, Gleichenella, Gleichenia, Rouxopteris, Sticherus, and Stromatopteris) with 160 extant species

  • The most ancestral in the Hymenophyllales (Lehtonen 2011)

  • This family is found in both the Old and New World tropics

Stems

  • Long creeping rhizomes

  • Stems are typically protostelic, with some steles containing parenchyma

Leaves

  • Large fronds that are several times pinnate.

  • Branching of the fronds is distinctive due to the presence of a so-called resting bud, which is formed by rachial dichotomies in which one part of the rachis is temporarily arrested in its growth

  • Petiole vascular strands may be solid or C-shaped with enrolled ends

Reproductive features

  • Sporangia occur in ring-shaped sori on the abaxial surface of the pinnule and there is no indusium (exindusiate)

  • The number of sporangia per sorus is usually small, but in some species may be up to 15 sporangia

  • Pinnule segments in some species are greatly reduced and cup-shaped

  • The annulus is transverse to oblique

Above: Ferns in the Gleicheniaceae. A,B. Gleichenia microphylla. A. Leaf showing pseudodichotomous branching of segments. B. Close-up of leaf, abaxial surface with dense trichomes. C,D. Sticherus cunninghamii. C. Leaf with pseudodichotomous branching of segments. D. Close up of sori, each with 3-5 sporangia. E,F. Dicranopteris linearis. E. Long, sprawling, pseudodichotomously branching leaf rachis. F. Pinnule close-up, abaxial surface, showing sori, each with numerous sporangia. (Images C,D from Lawrence Jensen; F from Gerald Carr)

Matoniaceae

  • 2 extant genera (Matonia and Phanerosorus); 4 extant species

  • This family is confined to Indonesia, Borneo, and New Guinea

  • Middle Triassic - present (Klavins et al. 2004)

  • 8 genera (Laccopteris, Phlebopteris, Matonidium, Matonia, Microdictyon, Weichselia, Tomaniopteris, and Konijnenburgia); 26 species

Stems

  • The rhizome is covered by hairs

  • The anatomy consists of two or three concentric amphiphloic siphonosteles, with leaf traces produced from the outer cycle

Leaves

  • Leaves of Matonia are palmately-dissected

  • Phanerosorus leaves are pendulous and pinnate.

Reproduction

  • Sporangia are massive and arranged in a ring around a receptacle that is the stalk of a peltate indusium

  • The position of the annulus is oblique, and spores are trilete

Above: Matonia pectinata