Key to Sri Lankan Marchantia species

1. Thallus margin lobulate or crenulate. Ventral scales in 4–6 rows extending over 75–100% of the thallus width. Laminal scales broader than long without apical papillae ................................................................................................................. M. polymorpha

- Thallus margin entire. Ventral scales in 4-rows extending over 16–66% of the thallus width. Laminal scales as long as or longer than wide, with apical papillae ...........................................................................................................................................................2

2. Inner opening of epidermal pore cruciate. Appendage of median scale entire or nearly so. Gemma cups with ciliate lobes and numerous papillae on outer surface. Male receptacles peltate ......................................................................................... M. paleacea

- Inner opening of epidermal pore with straight or convex wall, not cruciate. Appendage of median scales bluntly or sharply toothed. Gemma cups ciliate or nearly entire without papillae on outer surface. Male receptacle palmate ...................................................3.

3. Appendage of median scale yellowish. Male receptacles sessile. Female receptacles with involucres located underneath lobes...... ............................................................................................................................................................................................ M. acaulis

- Appendage of median scale purplish or hyaline not yellowish. Male receptacles stalked. Female receptacles with involucres alternating with lobes .........................................................................................................................................................................4

4. Appendage of median scale bluntly toothed. Female receptacle without shallow median projections, shallowly divided into 4–6 lobes, lobes not convex or broadened apically...................................................................................... M. pappeana subsp. robusta

- Appendage of median scale sharply toothed. Female receptacle with a conspicuous median projection, deeply divided into 5–13 lobes. Lobes convex and broadened apically .....................................................................................................................................5

5. Thallus with a dark median band on the dorsal surface. Mucilage cavities sometimes present in the ventral tissue. Appendage of median scales with a single apical cell or a row of 2–3 apical cells, marginal teeth oriented towards the apex of the appendage..... .......................................................................................................................................................... M. papillata subsp. grossibarba

- Thallus without a dark median band on the dorsal surface. Ventral tissue without mucilage cavities or rarely 1–2. Appendage of median scales with a row of 2–3 cells apically, marginal teeth, recurved towards the base of the appendage........... M. emarginata