Botany and Plant Science

The sporangiophores of Equisetum are stalked, peltate (shield-shaped) structures arranged in whorls to form the strobilus.

The prothallus is the independent, heart-shaped, haploid gametophytic phase in the life cycle of pteridophytes.

The protocorm is a tuber-like structure that develops during the early stages of the development of the sporophyte in certain species of Lycopodium.

Amphiphloic siphonostele, where phloem is present on both the inner and outer sides of the xylem, is a characteristic feature of the stem of Marsilea.

Equisetum spores possess hygroscopic, ribbon-like structures called elaters that help in spore dispersal.

The vascular bundles of Equisetum stems contain carinal canals, which are formed by the breakdown of protoxylem elements.

Equisetum plants are called scouring rushes because their stems contain significant deposits of silica, which makes them abrasive and useful for cleaning.

In pteridophytes, the main plant body is the sporophyte (2n). Meiosis or reduction division occurs during spore formation within the sporangia to produce haploid spores (n), which subsequently germinate into the gametophyte generation.

Equisetum is known to have very small antheridia that produce a small number of sperms compared to other pteridophytes.

All four statements are correct: Pteridophytes lack companion cells, xylem vessels are generally absent (except in some Gnetales/Selaginella), heterosporous ones have reduced gametophytes, and water is required for fertilization.

The protocorm is a specialized tuberous, chlorophyllous structure formed during the early development of the young sporophyte in certain species of Lycopodium after the gametophytic stage.

Equisetum (horsetail) is well known for its jointed, ribbed, and green stems, which perform photosynthesis and have distinct nodes and internodes.

Pteridophytes comprise of a group of roughly 12,000 species of vascular plants that reproduce via spores and have neither seeds nor flowers, e.g., fern. They differ from mosses by being vascular (i.e., having water-conducting vessels). They have stems and leaves like other vascular plants.