Lenormandia latifolia Harv. & Grev.

Scientific Description

Habit and structure. Thallus medium red to dark red-brown, with one (occasionally a few small lateral blades from the stipe) unbranched blade from a short stipe, blades usually 20–60(–80) cm long and (5–)10–20 cm broad, ovate to elongate, expanding from the short stipe upwards and broadest at half or more of the length, margin smooth, apex broadly tapering and rounded; midrib slight, not apparent in older blades, faintly visible in some young fronds. Holdfast discoid to divided, 2–5 mm across; usually epiphytic on Osmundaria, occasionally on Epiglossum smithiae, possibly also epilithic. Structure. Apices usually lost from mature plants, axial cells with 5 pericentral cells, clear only close to the apex; midrib; medulla 2–3 cells thick, cells irregularly arranged, cortex 1–2 cells thick with surface cells angular, more-or-less isodiametric and 12–30 µm across in surface view. Rhombic areolation apparent only near apices of young blades. Trichoblasts scattered on thallus surface, 1–2.5 mm long. Rhodoplasts discoid, often becoming chained.

Reproduction. Gametophytes dioecious. Procarps on lower cells of exogenous trichoblasts on the blade surface, the branchlets soon becoming polysiphonous. Carposporophytes with a basal fusion cell and branched gonimoblast with clavate terminal carposporangia 25–50 µm in diameter. Cystocarps ovoid to pyriform with a thick stalk, 0.5–1 mm in diameter; pericarp ostiolate, corticated, 4–6 cells thick, often with a side bulge. Spermatangial organs clustered on branches of surface trichoblasts, elongate-ovoid, 25–50 µm in diameter and L/D 3–4, with 1–3 sterile basal cells. Tetrasporangial stichidia in dense clusters scattered on the blade surface, stalked, elongate-ovoid to cylindrical, 200–280 µm in diameter and L/D 2–4, corticated, with paired tetrasporangia 60–100 µm in diameter.

Distribution.Yanchep, W. Aust., to Cape Northumberland, S. Aust.

Habitat. L. latifolia is common on rough-water coasts.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 389–390 (2003)]