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ORDER BANGIALES Schmitz in Engler 1892: 15

Phylum Rhodophyta – Class Bangiophyceae

Thallus (gametophyte) macroscopic, erect but flaccid, filamentous and uniseriate to multiseriate, or foliose and 1 or 2 cells thick; growth diffuse, without pit-connections; basal attachment multi-rhizoidal from numerous suprabasal cells. Rhodoplasts one (or two) per cell, stellate, each with a central pyrenoid. Sporophyte ("conchocelis" phase) minute, filamentous, uniseriate, branched, with primary pit-connections; rhodoplasts parietal, each with one to a few small pyrenoids.

Reproduction: Asexual reproduction by monospores (or aplanospores) from both generations, arising from undifferentiated vegetative cells.

Sexual reproduction by spermatia formed in packets of 64–256 by subdivision of vegetative cells, and carpogonia only slightly modified from vegetative cells and usually with a short prototrichogyne. The zygote dividing directly to form packets of 8, 16 or 32 carposporangia, with the carpospores developing into minute filamentous sporophytes (conchocelis phase) bearing "fertile cell rows" liberating spores (probably meio-) which reform the gametophyte thalli.

Life history heteromorphic, usually with a macroscopic gametophyte and microscopic sporophyte.

Taxonomic notes: Taxa of the Bangiales are characterised by their macroscopic form (usually 2–20 (–50) cm high), attachment by multi-rhizoidal bases, lack of pit-connections in the gametophytes but presence in the sporophytic phase, and well developed sexual reproduction.

The occurrence of sexual reproduction in this order, particularly in Porphyra, has been much debated over many years, but Hawkes (1978) has established its occurrence in P. gardneri (Smith & Hollenberg) Hawkes.

References:

ENGLER, A. (1892). Syllabus der Vorlesungen über specielle and medicinisch-pharmaceutische Botanik ... Grosse Ausgabe. (Borntraeger: Berlin.)

HAWKES, M.W. (1978). Sexual reproduction in Porphyra gardneri (Smith et Hollenberg)Hawkes (Bangiales, Rhodophyta). Phycologia 17, 329–353.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.


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