Laurencia

Laurencia obtusa, from here.

Belongs within: Rhodomelaceae.

Laurencia is a diverse genus of erect, often densely branching Rhodomelaceae.

Characters (from Womersley 2003): Thallus erect, moderately to much branched radially or distichously for 2–5 orders, soft to firm, usually drying cartilaginous, branches with truncated apices with a depressed apical pit; holdfast discoid or stoloniferous, epilithic or epiphytic. Structure. Apical depression with a central, short, apical filament bearing well-developed trichoblasts and four pericentral cells per axial cell, axial cells short, these and the pericentral cells soon obscured and not recognisable in sections, cortex extensive with relatively large, ovoid, usually compact, irregular cortical cells and a small-celled epidermis with secondary pit-connections between the cells lengthwise to the branch and usually with corps en cerise; inner cortical cells often producing rhizoids and in some species with lenticular wall thickenings. Lateral branches arising from basal cells of trichoblasts. Cells uni- or multinucleate; rhodoplasts discoid to elongate, often chained in larger inner cells. Gametophytes dioecious. Procarps formed on the fourth pericentral cells on the suprabasal cell of trichoblasts, consisting of a lateral sterile group of 4–6 cells, a four-celled carpogonial branch and a basal sterile group of 2–3 cells. Carposporophytes with a basal fusion cell and branched gonimoblast bearing clavate terminal carposporangia, usually replaced from cells below when lost. Cystocarps usually lateral on branches, usually sessile, basally constricted or broad-based and in some species conical; pericarp arising pre-fertilization, ostiolate, corticated and 3–6 cells thick. Spermatangia borne in lateral whorls on cells of modified trichoblasts in the apical cup-like depressions, each axial cell with four pericentral cells and ultimate spermatangia, the filaments terminated by an enlarged globular cell. Tetrasporangia borne, usually abaxially, on outer ends of laterally elongate pericentral cells or pit-connected to outer cortical cells, usually in "parallel" (down the branch) arrangement, tetrahedrally divided.

Laurencia Lamouroux 1813 (nom. cons.) W03
    |--*L. obtusa (Hudson) Lamouroux 1813 W03
    |--L. aldingensis Saito & Womersley 1974 W03
    |--L. arbuscula Sonder 1845 (see below for synonymy) W03
    |--L. botrychioides Harvey 1855 L27
    |--L. botryoides (Agardh) Gaillon 1828 (see below for synonymy) W03
    |--L. brongniartii Agardh 1841 [incl. L. concinna Montagne 1842, L. grevilleana Harvey 1855] W03
    |--L. clavata Sonder 1853 (see below for synonymy) W03
    |--L. cymosa Kützing 1865 W03
    |--L. distichophylla Agardh 1852 W03
    |--L. elata (Agardh) Hooker & Harvey 1847 (see below for synonymy) W03
    |--L. filiformis (Agardh) Montagne 1845 (see below for synonymy) W03
    |--L. forsteri (Mertens) Greville 1830 (see below for synonymy) W03
    |--L. gracilis Harvey 1847 L27
    |--L. hybrida (Desne) Kützing 1849 L27
    |--L. intricata W03
    |--L. majuscula (Harvey) Lucas 1935 [=L. obtusa var. majuscula Harvey 1863] W03
    |--L. papillosa (Agardh) Greville 1830 W03
    |--L. pinnatifida (Gmelin) Lamouroux 1813 L27
    |--L. shepherdii Saito & Womersley 1974 W03
    |--L. spectabilis Postels & Ruprecht 1840 S57
    |--L. tasmanica Hooker & Harvey ex Harvey 1849 [incl. L. excelsa Kützing 1865] W03
    |--L. thyrsifera Agardh 1876 L27
    |--L. uncinata Zanardini 1847 W03
    `--L. virgata (Agardh) Agardh 1852 L27

Laurencia arbuscula Sonder 1845 [incl. L. botryoides var. minor Harvey 1863, L. obtusa var. regia Harvey 1863, L. regia (Harvey) Yamada 1931] W03

Laurencia botryoides (Agardh) Gaillon 1828 [=Chondria botryoides Agardh 1817, Fucus botryoides Turner 1811 (nom. illeg.)] W03

Laurencia clavata Sonder 1853 [=Chondria clavata (Sonder) Harvey 1862, Corynecladia clavata (Sonder) Agardh 1876; incl. Corallopsis australasica Sonder 1853, Corynecladia auatralasica (Sonder) Sonder 1880, Chondria corynephora Harvey 1855, Ch. clavata var. dendroides Harvey 1863, Corynecladia umbellata Agardh 1876 (nom. illeg.)] W03

Laurencia elata (Agardh) Hooker & Harvey 1847 [=Chondria pinnatifida var. elata Agardh 1822, L. pinnatifida var. elata (Agardh) Sonder 1846; incl. L. elata var. luxurians Harvey 1863, L. luxurians (Harvey) Agardh 1876] W03

Laurencia filiformis (Agardh) Montagne 1845 [=Chondria filiformis Agardh 1822, Gracilaria filiformis (Agardh) Greville 1930; incl. L. affinis Sonder 1845, L. forsteri f. affinis (Sonder) Yamada 1931, Coeloclonium claviferum Agardh 1897, Dolichoscelis clavifera (Agardh) Agardh 1899, Laurencia forsteri f. delicatula Sonder 1848, L. filiformis f. dendritica Saito & Womersley 1974, L. forsteri f. dilatata Kützing 1865, L. forsteri f. elata Sonder 1848, L. forsteri f. fasciculata Agardh 1876, L. forsteri f. fragilis Sonder 1848, L. forsteri f. gracilis Sonder 1848 non L. gracilis Harvey 1847, L. heteroclada Harvey 1855, L. filiformis f. heteroclada (Harvey) Saito & Womersley 1974, L. forsteri f. pyramidata Agardh 1876, L. forsteri f. setacea Kützing 1865, L. forsteri f. subpinnata Agardh 1876] W03

Laurencia forsteri (Mertens) Greville 1830 [=Fucus forsteri Mertens ex Turner 1809, Chondria forsteri (Mertens) Agardh 1823] W03

*Type species of generic name indicated

REFERENCES

[L27] Laing, R. M. 1927. A reference list of New Zealand marine algae. Transactions and Proceedings of the New Zealand Institute 57: 126–185.

[S57] Scagel, R. F. 1957. An annotated list of the marine algae of British Columbia and northern Washington (including keys to genera). National Museum of Canada Bulletin 150: 1–289.

[W03] Womersley, H. B. S. 2003. The Marine Benthic Flora of southern Australia. Rhodophyta pt IIID. Ceramiales—Delesseriaceae, Sarcomeniaceae, Rhodomelaceae. Flora of Australia Supplementary Series 18. Australian Biological Resources Study: Canberra, and the State Herbarium of South Australia: Adelaide.