Lophosoria quadripinnata

Lophosoria quadripinnata
Lophosoria quadripinnata-fronda.JPG
Scientific classification e
Kingdom: Plantae
Division: Pteridophyta
Class: Polypodiopsida/Pteridopsida
(disputed)
Order: Cyatheales
Family: Dicksoniaceae
Genus: Lophosoria
Species: L. quadripinnata
Binomial name
Lophosoria quadripinnata
( J.F.Gmel.) C.Chr. 1920

Lophosoria quadripinnata ( J.F.Gmel.) C.Chr. is a species of fern that, according to DNA molecular analysis, belongs to the Dicksoniaceae family, where it is placed in the genus Lophosoria. It is found in the Americas spanning from Cuba and Mexico to Chile. In Chile it is present in the area between Talca and Aysén including Juan Fernández Islands. In Argentina it grows only in the humid valleys of western Neuquén and Río Negro Province. Diamondleaf fern is a common name. [1] In Spanish it is known as 'ampe' (from the Mapudungun añpe) or palmilla, but one has to remember that there are several species of ferns called "palmillas" that have larger or smaller fronds, and which grow in colder climates. It is a medium-sized plant, growing to about 4–5 feet (though 10–12 feet in a sheltered place at Arduaine Garden in Argyll, Scotland) and even though the rhizome does not grow a trunk, it is clearly related to the other tree ferns due to features that were apparently already present in their common ancestor, like 'pneumathodes', and the rhizome which changed from the dorsiventral symmetry typical of the other ferns, to a radial symmetry typical of tree ferns. Their large and multiple pinnate fronds, with the petiole raised adaxially, and the hairs on the rhizome and lower part of the petioles, also resemble those of tree ferns. To identify the species, use the position and characteristics of the spores found on the fertile fronds. The genus already existed in the Cretaceous Period in southern Gondwana according to fossil remains found in Antarctica. The species is well known as an ornamental plant.

Habitat of Lophosoria quadripinnata

Description

Lophosoria quadripinnata is a vascular plant with two alternating generations, a sporophyte and a gametophyte, multicellular and independent; with spores as a means of dispersion and survival. The gametophyte is a "thallus" (undifferentiated tissue), and the sporophyte is a "corm" (with roots, shoots, and a vascular system). Due to these characteristics it is usually classified as a " pteridophyte". They have sporophytes with megaphylls or "fronds" ( Euphyllophytina).

The rhizome is massive, with hairs, not growing a trunk (not arborescent), and with radial symmetry instead of horizontal; a characteristic apparently originating in the ancestor of the tree ferns. The fronds are large in size, 2-3 pinnations, with hairs on the under side of the petioles, and they are high on its abaxial part, all common characteristics of the Cyatheales order (the tree ferns clade). Also present are the pneumathodes (discrete vent lines, or patches, present on the rachis, petiole and rhizome, whose function is facilitating gas exchange in the dense tissue), which are characteristic of the tree fern clade.

Details of the adaxial face of the frond of Lophosoria quadripinnata

The sori, without indusia (covering), are located on the abaxial (lower) surface, on the veins of the last pinnae. The leaf margin does not form part of an indusium, as in other Dicksoniaceae. The sori have numerous hairs (called "filiform paraphyses") between the sporangia. The characteristics and position of the sori are unique and can be used to identify the species.

Like all Polypodiopsidas, the sporangia are leptosporangiate (with a foot, capsule with a single-cell wall thickness, and dehiscent ring in the capsule). As in all the tree ferns, the ring is oblique and complete, not interrupted by the foot of the sporangium. The spores have trilete marks. This species has spores with a very unusual morphology, with a central belt ("cincture") that meant for a long time the species was assigned its own family, Lophosoriaceae.

The germination of the gametophyte corresponds to the Cyathea genus, giving rise to short strands of from two to six cells in both varieties. The prothallus development is of the Adiantum type. When raised in the laboratory, gametophytes of the quadripinnata variety are always chordates, however gametophytes of the contracta variety possess three morphs, depending on the density of spores that are developed (Dyer 1979 [2]). At low density, they are long spatulates with a central meristem and a slightly more developed wing than the other; at medium densities they are cordiforms and at high densities are band-like with a large amount of antheridia.

The gametophyte is protandric (a hermaphrodite, first antheridia are developed that give antherozoids, and then the archegonia that gives the oospheres). The number of x chromosomes = 65.