Ricciocarpos

Free-floating aquatic or stranded on mud when water recedes, perennial, monoicous or sometimes dioicous. Thallus once to repetitively forked, forming irregular groups or radiating out from a central point to form a semi-circular to flabelliform outline, yellow-green, occasionally tinged with red to purple marginally, glabrous, adaxially with a persistent narrow groove along midline; margins plane. Photosynthetic tissue of thallus divided vertically into 3–4 irregular tiers of air chambers with specialised pores at surface. Storage tissue reduced to 3–4 layers of cells at its thickest and reduced to the abaxial epidermis toward margins. Oil cells present in adaxial epidermis, storage tissue and abaxial scales. Abaxial scales in several rows, small and oblong to lingulate when on mud, large, linear and lanceolate when floating, purple, non-photosynthetic, denticulate. Adaxial epidermal cells chlorophyllose, thin-walled, persistent even when old, giving surface a leathery appearance. Rhizoids absent or rare when floating, abundant when on mud, with few internal peg-like thickenings, but mostly smooth. Capsules remaining embedded in thallus through maturation, present only when aquatic. Spores rounded-tetrahedral with a convex distal face and a proximal face without a triradiate ridge, faintly granulate-areolate, brown to black, shed singly.