Question

An adaxial outgrowth from the base of leaves in Selaginella is called
A. Stipule
B. Ligule
C. Trabaculae
D. Velum

Answer 1

Hint:Selaginella is a pteridophyte also called little club moss or spike moss. Some specialized structures like Rhizophora, ligule, glossopodium are found in Selaginella. It has a haplodiplontic life cycle with heteromorphic alternation of generations.

Complete answer:Selaginella belongs to the genus of vascular plants in the family Selaginellaceae. Selaginella is also known as little club moss or spike moss. The sporophytic plant is differentiated into stem, leaves, and roots. The roots develop at the tips of special branches called rhizophores. These are leafless, colorless, positively geotropic, cylindrical structures.
Rhizophore of Selaginella is also called as organ sui generis (an organ having the characters of both stem and root).
Leaves are simple, sessile, and microphyllous and each one bears a small scale called ligule on the basal adaxial surface. Such leaves are called ligulate leaves. Leaves have chloroplast with pyrenoid like structures. At the base of a ligule, there is a sheath of elongated cells called glossopodium.
A stipule is part of the anatomy of the leaf, present as an outgrowth borne on either side of the base of leafstalk.
Trabeculae is a microscopic structure that supports the plant.
Velum is a thin membranous covering of the sporangia close to the leaf base in quillworts.
So, our correct answer is option B. ligule.

Note:Xerophytic species of Selaginella, under dry conditions, roll into brown balls and thus the root system is disorganized. This process is known as cespitose habit. When moist conditions come, these brown balls unroll again and become green colored. Because of this phenomenon, these plants are called resurrection plants.