Porella Platyphylla LichenPorella platyphylla, (L.) Lindle.
Plant (gametophyte).-Stems 2 or 3 inches long, prostrate, rigid with the tips bent upward; 1 to 3 times regularly or irregularly pinnate; root-hairs in tufts at the base of the under-leaves.
Leaves.-Deeply two-parted, dorsal lobes overlapping in two rows so as to conceal the stern, obliquely placed relatively to the stern, oval to oblong, apex obtuse, toothed or entire. Ventral lobes oval to oblong obtuse, diagonally pressed to the surface of the upper lobes; margins recurved and entire or with a single tooth at the base; under leaves tongue-shaped, parallel with the stem, margins recurved, decurrent, entire, or sparingly toothed at the base.
Name.-The specific name Platyphylla from the Greek; flat, and a leaf, describes the prostrate habit of the plant.
Perianth.-Ovate, inflated, narrowed above, margin toothed with a notch on one side.
Veil (calyptra).-Persistent, globose, splitting above.
Spore-case.-Pale yellow-brown on a short pedicel, splitting
into four, often irregular valves; elaters bi-spiral.
Spores.-More or less spiny.
Habit of flowering.-Male flowers (antheridia) and female flowers (archegonia) on separate plants (dioicous).
Antheridia.-Spherical, short-stalked, single in the axils of two-lobed, pouch-shaped leaves which lie opposite on the stem. These antheridial leaves are united by their margins to the under leaves, and with them form short oval branchlets on the sides of the main branches.
Archegonia. - Numerous, terminal on very short lateral branches.