Brief account and life cycle of Ophioglossum
Ophioglossum:-
1. Systematics:-
Division:- Pterophyta
Class:- Pteropsida
Order:- Ophioglossales (Marginales)
Family:- Psilotaceae
Genus:- Ophioglossum
2. Habit and Habitat:-
> Ophioglossum (45 species) is cosmopolitan in distribution.
> It is found in plane areas as well as hilly areas of subtropical zones.
> Its origin takes place in hilly areas and migration into plane areas takes place by water.
> It is also found in Rajasthan.
- In Sri Ganganagar, it is found near Kaliyan in the form of bunch.
- Rivers of Kota and Rawatbhata.
> Common Name:- Adder's tongue fern (Adder = snake). Its spike giving the appearance of tongue of snake.
> Common species:–
i. O. reticulatum:- Distributed throughout India.
ii. O. vulgatum:- North-West Himalaya and widely distributed in temperate zones through out India.
iii. O. palmatum
iv. O. simplex
Note:- Ophioglossum is considered to be having highest number of chromosomes among plant kingdom.
2n = 1262 + 10 fragments
> Ophioglossum is being treated by some authers as a genus of four subgenera:-
i. Euophioglossum:- Majority of species.
ii. Ophioderma:- O. pendulum.
iii. Cheirogloass:- O. palmatum.
iv. Rhizoglossum:- O. berginianum
3. Study of sporophyte:-
> In most of the species of Ophioglossum and Botrychium the sporophyte has a short, erect, subterranean rhizome. In O. pendulum and, intermedium the rhizome is markedly dorsiventral.
> The lamina of the leaf in most species except in few species as e.g. O. palmatum is simple, entire and narrowly linear to broadly oval in outline.
> In O. palmatum the mature leaves are more or less clearly dichotomous and the lamina is palmately divided into a number of norrow lobes.
> In O. pendulum the long, pendent leaf may reach a length of 1.5 mm or more.
> The roots may be unbranched in sub genus Euophioglossum or branch freely in subgenus ophionderma or branch freely in subgenus churoglossa.
> The roots are mycorrhizic.
4. Reproduction:-
> The sporangia are born on fertile spike that arise on the basal portion of the sterile leaf.
> After maturity the sporangium delisces by a transverse cleft in Ophioglossum.
> L.S. spike or cone:- All sporangia are at the same stage of development.
> Prothalus:- Spore germinates to give rise subterrenian prothallus.
> Embryo is always exoscopic.
5. Phylogeny:-
> Phylogeny:- The history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms.
