Electronic Flora of South Australia Genus Fact Sheet

Genus LESSONIA Bory 1825b: 23

Phylum Phaeophyta – Order Laminariales – Family Lessoniaceae

Thallus 1–4 m high, with a discoid, divided and becoming conical, or ligulate holdfast attached by branched haptera, with the stipe branched from the base or above, often twisted, with each branch bearing a blade; pneumatocysts absent. Growth by splitting near the base of the blades, extending through the transition region. Blades simple, 0.5–2m long and 1–5 (–8) cm broad, ligulate to irregularly elongate-ovate, flat, margins entire to spinous, surface smooth to rugose or corrugate. Structure with a central, filamentous medulla, extensive cortex of relatively small cells with or without mucilage cavities, and outer layer of meristoderm; outer cells densely phaeoplastic.

Reproduction: Reproduction by unilocular sporangia (with paraphyses) in extensive sori on the surface of the blades.

Type species: L. flavicans Bory.

Taxonomic notes: Gametophytes dioecious, filamentous, oogamous.

A genus of about 6 species (Searles 1978; Villouta & Santelices 1986), mainly South American and subantarctic in distribution, with one species in New Zealand and one in Tasmania.

The species of Lessonia differ in the nature of the holdfast, the extent of stipe development (from slight in L. corrugata to a massive "trunk", much branched above, in some S. American species), the form of the blades, and the presence or absence of mucilage cavities in the blades.

References:

BORY DE ST-VINCENT, J.B. (1825b). In Dumont-Durville, J., Fore des Isles Malouines, pp. 1–50. (Paris-as a separate.)

SEARLES, R.B. (1978). The genus Lessonia Bory (Phaeophyta, Laminariales) in southern Chile and Argentina. Br. phycoL J. 13, 361–381.

VILLOUTA, E. & SANTELICES, B. (1986). Lessonia trabeculata sp. nov. (Laminariales, Phaeophyta), a new kelp from Chile. Phycologia 25, 81–86.

The Marine Benthic Flora of Southern Australia Part II complete list of references.

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
©Board of the Botanic Gardens and State Herbarium, Government of South Australia


Disclaimer Copyright Disclaimer Email Contact:
State Herbarium of South Australia
Government of South Australia Government of South Australia Department of Environment, Water and Natural Resources