Plant Biology and Classification

Cyphellae are small, pore-like structures found on the lower cortex of certain lichens that facilitate gas exchange, functioning analogously to stomata in higher plants. Soredia and isidia are structures used for vegetative reproduction.

In lithosere (xerosere or xerarch), the pioneer community is usually constituted by crustose lichens(e.g., Graphis, Rhizocarpon). Foliose lichens(e.g., Dermatocarpon, Parmelia) kill the crustose lichens by shading them, cause deeper depressions and accumulate more soil particles and organic matter. Foliose lichens make the conditions favourable for the growth of hardy mosses(e.g., Tortula, Grimmia).

Lichen forms a crust over bare rocks and starts forming soil from their organic remains by secreting carbonic acid which results in the chemical breakdown of rocks. 

Selaginella is a classic example of a heterosporous pteridophyte, producing both microspores and megaspores.

The strobili of Selaginella or spike moss is heterosporous. It bears both microsporangium and megasporangium on the axis of the microsporophyll and megasporophyll respectively. The strobili with the sporophylls arranged look like a spike or a cone.

Rhizophores are leafless axial organs, which apices are the only sites for root formation  are unique to the Selaginella genus. Both rhizophores and roots are dichotomously branched, forming a multibranch rhizophore root system.

Heterospory is the production of two different types of spores by the sporophytes of land plants. Of all the options given in the question Selaginella, Pinus and Cycas all produce micorspores and megaspores for reproduction. However, Pteridium on the other hand is homosporous.

Pteridophytes are divided into four classes: Psilopsida, Lycopsida, Sphenopsida and Pteropsida. Selaginella belongs to Lycopsida. Selaginella has small leaves called microphylls. Sporophylls are compactly arranged into structures called strobili or cones. They are heterosporous as they produce two types of spores, macro (large) and micro (small).

The correct answer is 'lycopsida'

Pteropsida is the class that includes the true ferns.

Heteromorphic alternation of generation means a sporophytic phase and gametophytic phase alternate each other. Eg: Dryopteris

The multiflagellated antherozoids of Dryopteris, point out that they originated from aquatic ancestors. In auatic environment the multiflagellated antherozoids swim in the water and fertilize the egg. Water is necessary for the fertilisation process. It proves their aquatic ancestry.

The polycyclic condition is the most complex of stelar organization found among pteridophytes. It is a dictyostele consisting of two or more concentric rings of meristeles. It occurs in Pteridium sp. 

The class Pteropsida is characterized by pteridophytic plants, that have large, dissected leaves and sporangia, that are borne on the leaves. Pteropsida is divided into three classes - (i) filicineae, (ii) gymnespermae, (iii) angiospermae.