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*''H. sanjuanensis''
*''H. sanjuanensis''
*''H. yessoensis''
*''H. yessoensis''

==Stonehenge==
The presence of H. rivularis near [[Stonehenge]] has been put forward as a reason for the site's perceived mystical properties. Flint in pools near the henge takes on a pink hue a couple of hours after being taken out of water due to the presence of the algae. It is assumed that ancient hunter-gatherers would have seen the rocks as having magical properties and would have deemed the site worthy of interest.<ref name="henge">{{cite web | url=http://www.dailymail.co.uk/sciencetech/article-2624129/Stonehenge-LONDON-Mesolithic-River-Avon-acted-like-A-Road-ancient-log-boats-expert-claims.html | title=Stonehenge was the 'LONDON of the Mesolithic': River Avon acted like an 'A-Road' for ancient log boats, expert claims Read more: http://www.dailymail.co.uk/sciencetech/article-2624129/Stonehenge-LONDON-Mesolithic-River-Avon-acted-like-A-Road-ancient-log-boats-expert-claims.html#ixzz3EMRCgyKp Follow us: @MailOnline on Twitter | DailyMail on Facebook | publisher=Daily Mail | accessdate=25 September 2014}}</ref>


== References ==
== References ==

Revision as of 20:22, 25 September 2014

Hildenbrandia
The darker red alga encrusting this rock fragment is H. crouaniorum
SEM of a H. rivularis gemma. Scale bar: 50 μm
Scientific classification Edit this classification
Clade: Archaeplastida
Division: Rhodophyta
Class: Florideophyceae
Order: Hildenbrandiales
Family: Hildenbrandiaceae
Genus: Hildenbrandia
Nardo, 1834

Hildenbrandia is a genus of thalloid alga comprising 26 species. The slow-growing, non-mineralized thalli take a crustose form.[1] Hildenbrandia reproduces by means of conceptacles and produces tetraspores.

Morphology

Hildenbrandia cells are around 3–5 μm in diameter and the filaments are around 50–75 μm in height.[2]

The thallus comprises two layers; the hypothallus, which attaches to the rock, and the perithallus, a pseudoparenchymous layer comprising vertical filaments, which unlike coralline red algae is not further differentiated.[3][4]

Growth

Hildenbrandia comprises orderly layers of vertical oblong cells with thick vegetative cell walls, occasionally connected by secondary pit connections with pit plugs in the septal pores.[5] It grows at its margins, away from the centre, and is able to quickly repair any gaps arising by regenerating from a basal layer of cells.[6] As plants become more mature, they become multi-layered and strongly pigmented near their centres, whilst their single-layered margins begin to grow more slowly.[6] Multi-layered areas may develop in the margins; these will detach and float away as gemmae to form new colonies, leaving a single layer of cells beneath them once they separate from the host plant.[6]

Newly settled gemmae form rhizoids.[7]

Conceptacles develop in a haphazard manner; cells in conceptacle regions deform one another and become less regularly shaped as they grow larger.[5]

In a similar fashion to the coralline algae, the outer layer of the thallus is shed seasonally, presumably to avoid colonization by epiphytes.[8]

Habitat

The freshwater species H. rivularis[6] and H. angularis[7] seems to form a clade,[9] and require an alkaline pH and hard water, preferring clean water.[10] Unlike most other freshwater red algae (which prefer running water), H. rivularis prefers still water, particularly shady lakes or ponds.[10] H. rubra and other marine species are found in brackish waters, but freshwater / gemma-bearing species cannot tolerate even moderate salinities.[11] The genus is often found in a symbiotic partnership with fungi.[12] Hildenbrandia has a remarkable tolerance to stresses including extreme temperatures, desiccation, and Ultra-violet light; it can be up and photosynthesizing near full capacity just minutes after being cooled to −17 °C or subjected to extreme salinities.[13]

Reproduction

Sexual reproduction has never been observed in any Hildenbrandia species.[11] It can reproduce by splitting into multiple colonies by fragmentation, or via stolons (i.e. sending out lateral branches) or gemmae.[6]

Marine Hildenbrandia, on the other hand, reproduce by means of tetraspores that are produced within the thallus by conceptacles.[7]

Systematics

The genus contains these species[14] (this list is out of date):

  • H. angolensis
  • H. arracana
  • H. canariensis
  • H. crouanii
  • H. crouaniorum
  • H. dawsonii
  • H. deusta
  • H. expansa
  • H. galapagensis
  • H. kerguelensis
  • H. lecannellieri
  • H. lithothamnioides
  • H. nardiana
  • H. occidentalis
  • H. pachythallos
  • H. patula
  • H. prototypus
  • H. ramanaginaii
  • H. rivularis
  • H. rosea
  • H. rubra
  • H. sanjuanensis
  • H. yessoensis

Stonehenge

The presence of H. rivularis near Stonehenge has been put forward as a reason for the site's perceived mystical properties. Flint in pools near the henge takes on a pink hue a couple of hours after being taken out of water due to the presence of the algae. It is assumed that ancient hunter-gatherers would have seen the rocks as having magical properties and would have deemed the site worthy of interest.[15]

References

  1. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1016/0022-0981(94)90143-0, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1016/0022-0981(94)90143-0 instead.
  2. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1080/09670260010001735731, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1080/09670260010001735731 instead.
  3. ^ "Hildenbrandia Ben: Morphology". washington.edu.
  4. ^ Cabioch, J.; Giraud, G. (1982). "La structure hildenbrandioïde, stratégie adaptative chez les Florideés". Phycologia (in French). 21 (3): 308–315. doi:10.2216/i0031-8884-21-3-307.1.
  5. ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1080/00071618200650331, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1080/00071618200650331 instead.
  6. ^ a b c d e Attention: This template ({{cite jstor}}) is deprecated. To cite the publication identified by jstor:2439969., please use {{cite journal}} with |jstor=2439969. instead.
  7. ^ a b c Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1046/j.1440-1835.2000.00208.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1046/j.1440-1835.2000.00208.x instead.
  8. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1080/00071618800650021, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1080/00071618800650021 instead.
  9. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1046/j.1529-8817.2003.01050.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1046/j.1529-8817.2003.01050.x instead.
  10. ^ a b Eloranta, P.; Kwandrans, J. (2004). "Indicator value of freshwater red algae in running waters for water quality assessment" (PDF). International Journal of Oceanography and Hydrobiology. XXXIII (1): 47–54. ISSN 1730-413X.
  11. ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.2216/i0031-8884-41-1-87.1, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.2216/i0031-8884-41-1-87.1 instead.
  12. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1046/j.1529-8817.1999.3510171.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1046/j.1529-8817.1999.3510171.x instead.
  13. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1007/978-1-4020-6112-7_9, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1007/978-1-4020-6112-7_9 instead.
  14. ^ Guiry, M.D.; Guiry, G.M. (2008). "Hildenbrandia". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Retrieved 2009-04-18.
  15. ^ "Stonehenge was the 'LONDON of the Mesolithic': River Avon acted like an 'A-Road' for ancient log boats, expert claims Read more: http://www.dailymail.co.uk/sciencetech/article-2624129/Stonehenge-LONDON-Mesolithic-River-Avon-acted-like-A-Road-ancient-log-boats-expert-claims.html#ixzz3EMRCgyKp Follow us: @MailOnline on Twitter". Daily Mail. Retrieved 25 September 2014. {{cite web}}: External link in |title= (help); Text "DailyMail on Facebook" ignored (help)
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