Electronic Flora of South Australia Genus Fact Sheet

Genus GIFFORDIA (Batters) Hamel 1939b: x

Phylum Phaeophyta – Order Ectocarpales

Thallus filamentous, uniseriate, much branched, tufted or forming loose entangled masses, attached by rhizoids, with branches often tapering into false hairs. Growth by meristematic regions (usually well defined, vague in some species) at the base of each branch. Cells with numerous discoid phaeoplasts, each with a pyrenoid.

Reproduction: Reproduction by plurilocular neutral sporangia, unilocular meiosporangia, and in some species by gametangia (apparently male and female gametangia in some species); reproductive organs usually sessile, borne below and above the meristematic zones.

Type species: G. secunda (Kützing) Batters.

Taxonomic notes: Giffordia, a genus of 7 or 8 species, is distinguished from Feldmannia largely by its habit, being much branched plants with meristematic regions at the base of each lateral and the laterals are relatively short, in contrast to the relatively very long, unbranched filaments terminating the meristematic regions in Feldmannia. In Giffordia, the sporangia occur both above and below the meristematic regions, and they are normally sessile.

References:

HAMEL, G. (1939b). Phéophycées de France. Fasc. V, pp. 337–432, i-xlvii. (Paris.)

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

KEY TO SPECIES OF GIFFORDIA

1. Thallus forming loose tangled masses, branching sparse and usually many cells apart; plurilocular sporangia plentiful to rare, scattered, conical; unilocular sporangia on separate plants; in calm water habitats

G. sordida

1. Thallus forming distinct tufts a few mm to 10 cm long, branching frequent along the main axes or laterals; plurilocular sporangia usually abundant; unilocular sporangia present on plants bearing plurilocular sporangia; in moderate to strong water movement

2

2. Plurilocular sporangia usually in series (often adaxial) from each cell of laterals, occasionally more scattered, elongate-ovoid to conical

G. sandriana

2. Plurilocular sporangia usually separated, rarely more than 2 or 3 on adjacent cells (sometimes so in G. mitchelliae but then sub-cylindrical)

3

3. Plurilocular sporangia straight, sub-cylindrical with slightly tapering and rounded ends

G. mitchelliae

3. Plurilocular sporangia usually upwardly curved, broadest near their base and usually tapering above, not sub-cylindrical but conical to ovoid or subspherical

4

4. Thallus usually with occasional to frequent opposite branches, rarely with branches alternate only; plurilocular sporangia subspherical to ovoid, asymmetric, often mostly unilateral and adaxial on the laterals

G. granulosa

4. Thallus usually with only irregularly alternate laterals; plurilocular sporangia ovoid to elongate-ovoid, scattered irregularly (sometimes clustered) on all sides of laterals

G. ovata


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