Riccia Kingdom: Plantae Division: Marchantiophyta Class: Marchantiopsida Order: Marchantiales Family: Ricciaceae Genus: Riccia External Morphology • Dorsiventrally differentiated, prostrate, fleshy thallus showing dichotomous branching to form rosettes • Each branch of the thallus is either wedge-shaped or linear • The dorsal surface of the green, fleshy thallus is generally thick in the centre and gradually becomes thinner towards the margin • Middle portion has a median groove or furrow on the dorsal surface running through the entire length of the thallus and is termed the midrib • At the distal end of the dorsal groove, lies an apical notch or a depression which protects the growing point Rhizoids • The ventral surface of the thallus shows numerous, unicellular rhizoids that not only help in attaching the thallus to the substratum but also help in the uptake of water and minerals • Rhizoids are of two types: smooth-walled and tu...