Systematics, Reproduction and Phylogeny of Tmesipteris

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Tmesipteris:-

1. Systematics:-

Division:- Psilophyta

Class:- Psilotopsida

Order:- Psilotales

Family:- Psilotaceae 

Genus:- Tmesipteris 

2. Habit and Habitat:-

> Tmesipteris is restricted to certain lands in the Southern Pacific, notably Australia, New Zealand and New Caledonia. 
> In New Zealand this hanging epiphyte is common in the warm temperate rain forests of both main islands, where it can normally be found as short spiky dark-green fronds (10–15 cm long), often with lighter bag-like sporangia at the bases of some of its "leaves".
3. Study of sporophyte:-
> Each plant consists of an aerial portion and a rhizome, or subterranean region, but has no roots. 
> The plant possesses no true leaves, what appear to be leaves are flattened stems. 
> The fronds emerge directly from the fibrous root-mats which clad the trunks of mature tree ferns such as Dicksonia and Cyathea.
> Aerial part varied from 3 to 8 inches in length.
4. Reproduction:-
> Pointed-ended sporangia are fused in pairs and lie on the upper surface at the base of forked fertile leaves.
> Single layer jacket is found.
> Inner cells undergoes meiosis to produce haploid spores. 
> All the spores produced in synangium are similar in shape, structure, behaviour and function, so called homospores.
> Each mature spore having a single median furrow or slit. 
> Spore is able to germinate to produce haploid thallus like gametophyte, called prothallus. It is underground. Inner cells have mycorrhizal association.
> Prothallus is homothallic or monoecious and protogynous (Archegonium mature first).
> Sex organs are embedded in the prothallus.
> Atheridia are globose type and antherozoids are spirally coiled and multiflagellated.
> Archegonium is flask shaped structure. Two neck cells are found. Neck canal cells may be two uninucleated or one binucleated. Venter wall is formed by adjoining prothallial cells.
> Embryo is exoscopic type, which germinate to give rise new plant.

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.