Class Filicineae: Classification and Characters | Pteridophyta | Botany

The Class Filicineae is a comparatively larger group than other Classes of Pteridophytes and contains about 175 genera with 8,000 species. The members are very varied in their habit and habitat. Some of the genera are cosmopolitan in their distribution, while others are strictly endemic. The earliest members of Filicineae appeared in the Devonian but it is believed that the ancestors of the present-day ferns evolved during the Triassic and Jurassic.

Classification of Filicineae:

Smith (1955) classified all the ferns in a single Class Filicineae which was divided into three subclasses:

I. Friliofilices:

Sporangia are borne on pedicels with vascular bundles; they are elongated and have a jacket more than one cell in thickness.

3 Orders:

(a) Protopteridales,

(b) Coenopteridales and

(c) Archaeopteridales. (All fossil ferns are included in three Orders).

II. Eusporangiatae:

Sporangia are borne on fertile spike or in sori on the upper surface of leaf blade. Each sporangium is deve­loped from a group of initial cells. Sporangial jacket is more than one cell in thickness.

2 Orders:

(a) Ophioglossales and

(b) Marattiales.

III. Leptosporangiatae:

Sporangium is developed from a single initial cell. Sporangial jacket is one cell in thickenings.

3 Orders:

(a) Filicales,

(b) Marsileales and

(c) Salviniales.

Pichi-Sermolli (1959) thinks that the sub-divisions of Filicineae into Eusporangiate and Leptosporangiate (a distinction established by Goebel) is rather artificial, since they include certain ferns for example, the Ophioglossales, and the Marattiales resembled in that the sporangia originated in the same way, but are not closely related.

He has subdivided the Class Filicineae into seven sub­classes:

i. Primofilicidae,

ii. Ophioglossidae,

iii. Marattiidae,

iv. Osmundidae,

v. Filicidae,

vi. Marsileidiae and

vii. Salviniidae.

Pichi-Sermolli, however, does not present any scheme of phylogenetic evolution of ferns.

Characters of Filicineae:

(i) The plant body is an axis without roots,

(ii) With emer­gences rather than leaves,

(iii) The sporangium on axis-tips,

(iv) The sporangium with massive and undifferentiated wall, and with, central sterile columella.

These characters are not found in any other groups, Psilotaceae with their chambered sporangia and elaborated anatomical structure form on Independent Order Psilotales under the Class Psilo­phytineae.