AP BIOLOGY

Detailed explanation-1: -The hydrophytic features include the presence of canals and reduced vascular tissues while the presence of thick cuticles, sunken stomata, green stems and reduced leaves indicate the xerophytic features.

Detailed explanation-2: -The outer cortex is chlorenchymatous, while the inner cortex is made up of thin-walled parenchymatous cells. There is a large air cavity in the inner cortex corresponding to each furrow and alternating with the ridges, known as vallecular canal.

Detailed explanation-3: -The xerophytic features are: (i) Ridges and furrows in the stem(Reduce surface area), • (ii) Deposition of silica in the epidermal cells, • (iii) Sunken stomata (reduce transpiration rate), • (iv) Reduced and scaly leaves(reduce surface area), and • (v) photosynthetic tissue in the stem in addition to leaves.

Detailed explanation-4: -The leaves of horsetails are arranged in whorls fused into nodal sheaths. The stems are usually green and photosynthetic, and are distinctive in being hollow, jointed and ridged (with sometimes 3 but usually 6–40 ridges). There may or may not be whorls of branches at the nodes.