Classification of Marattidae: 4 Families | Plants

The following points highlight the four families under which marattidae has been classified. The families are:- 1. Angiopteridaceae 2. Marattiaceae 3. Christenseniaceae 4. Danaeaceae.

Family # 1. Angiopteridaceae:

Sporangia almost free, arranged in two rows on two sides of vein forming linear sori near margin.

Genera:

Angiopteris (100 spp. from Polynesia to Madagascar and the Himalayas), Archangiopteris (4 spp. from S.E. Asia) and Macroaglossum (2 spp. from Melanasia).

Family # 2. Marattiaceae:

Sporangia forming linear oval synangia.

Genera:

Marattia (60 spp.) and Protomarattia (1 sp.). Pantropical.

Family # 3. Christenseniaceae (=Kaulfussiaceae):

Christenseniaceae (=Kaulfussiaceae); sporangia radially arranged to form circular synangia.

Genus:

Christensenia (=Kaulfussia) (1 sp. from Indomalesia)..

Family # 4. Danaeaceae:

Linear long synangia (leaf middle to margin) very close together, almost covering lower outer half of leaf.

Genus:

Danaea (32 spp. from tropics of New World).

Angiopteris evecta (Fig. 610A & B) is found all over India and specially in the Eastern Himalaya (up to 2500 metres), Assam and Chittagong.

Marattia fraxinea (Fig. 610C) is found in South India (4-6000 ft.). Christensenia (=Kaulfussia) aesculifolia (Fig. 610D & E) is found in North as well as East India. Angiopteris, which is more primitive, shows a chromosome number n= 40 and 80. Marattia, which is more ad­vanced, shows n = 78.

The Sporophyte:

The sporophyte stem is short (although it may be half a metre or more in dia­meter), radial (sometimes dorsiventral) and covered by persistent leaf bases. There is a crown of compound leaves (pinnate leaves of Angiopteris evecta are reported to reach a length of 5 metres) at the apex.

Leaves show circinateptyxis and each leaf has a pair of stipules at its base and the stem surface below is covered by a mantle of leaf bases or leaf scars each with two persistent stipules. The stem has numerous long adventitious roots, one or more inserted below each leaf or leaf scar.

The growing apex has at first a single cell which is later replaced by a group of meristematic cells. In the stem, the cortex is uniformly parenchymatous and contains a number of mucilage canals and tannin-filled cells (Fig. 611). Young stems and lower portions of old stems have endodermis but late mature portions show no delimitation between cortex and stele.

The vascular cylinder is protostelic at base but it abruptly becomes siphonostelic a little higher up. In the lower regions there is a single trace departing to each leaf but higher up two strands depart for each leaf breaking up the siphonostele into meristeles.

The vascular strands further subdivide when mature, breaking up into strands arranged in concentric circles looking like the disintegration of a polycyclic system. Complications further increase by peculiar branches called commissural strands which run diago­nally across the pith and often form an internal ring.

Root traces come out only from meristeles of the inner rings. The pith is homogeneous like the cortex but it is full of branch or commissural strands in mature parts.

The root cortex also is full of mucilage canals and, in the young stage, contains an oomycetous endophytic fungus.

The sporangia grow in linear sori or linear and circular synangia (formed by the coalescence of sporangia) formed by 12 to 36 sporangia (Fig. 610 B, C & E). These develop as massive structures from epidermal patches of tissues and may even contain stomata on the multi-layered walls.

The innermost layer of the jacket acts as the tape­tum. There is no annulus, the sporangia rupturing though the middle of the jacket after splitting apart of the individual sporangia in case of a synangium. A huge number of spores is formed in each sporangium.

Gametophyte:

Gametophytes or prothalli of Marattiales are bigger than those of modern ferns. They are dark-green, fleshy (multi-layered) and externally resemble liverworts like Pellia. They may be ribbon-shaped, spathulate or heart-shaped. Rhizoids are on the under surface. There is an endophytic fungus in the thallus but it is supposed to be more parasitic than symbiotic in nature.

There is a strong midrib. The gametophytes are monoecious. Antheridia are formed early on the ventral side of the midrib but may later grow on the dorsal side as well. Archegonia grow only on the doisal side of the midrib. Antheridial and archegonial development resembles Ophioglossum generally. The sperms are multiciliate and they grow in large numbers.

New Sporophyte:

The first division of the zygote is transverse. Differentiation of the embryo is late as in the Eusporangiates. It seems that the epibasal part gives rise to foot and the hypo­basal part to the root, the cotyledon and the stem. The new sporophyte comes out by the cotyledon piercing the calyptra. The stem develops after the root.

The suspensor has been reported in the Marattiales inconstantly. It has been reported in Angiopteris only occasionally. It has also been reported in Danaea and Macroglossum but not in most species of Angiopteris or any species of Marattia. It is possibly a vestigeal organ reciting the primitive nature.