[[File:Cladonia coniocraea guwak 114 1.jpg|thumb|Podetia rising up from the primary thallus of ''Cladonia coniocraea'']] A '''podetium''' (plural: '''podetia''') is the upright secondary thallus in ''Cladonia'' lichens. It is a hollow stalk extending from the {{lichengloss|primary thallus}}.<ref>{{Cite book|title=Macrolichens of the Pacific Northwest|last1=McCune|first1=Bruce|last2=Geiser|first2=Linda|publisher=Oregon State University Press|year=2009|isbn=978-0870715655|pages=446}}</ref> Podetia can be pointed stalks, club like, cupped, or branched in shape and may or may not contain the ascocarp, the fruiting body, of the lichen.<ref>{{citation |author1=Brodo, I.M. |author2=Sharnoff, S.D. |author3=Sharnoff, S. |author4=Canadian Museum of Nature |year=2001 |title=Lichens of North America |publisher=Yale University Press |isbn=9780300082494 |url=https://books.google.com/books?id=YyS-hS15Ty4C |page=761}}</ref> It is not considered part of the primary thallus as it is a fruiting structure for reproduction. A lichen can be described as "podetiate" when it forms a podetium.
==Structure and development==
Podetia are unique expanded structures produced at the tips of the {{lichengloss|primary thallus}} in ''Cladonia''. They are produced in three sections of ''Cladonia'': true {{lichengloss|scyphi}}, {{lichengloss|verticillate}} podetia, and funnel-like structures. The development of podetia is highly variable, with growth rates depending on species and environmental conditions. Annual growth typically ranges from 1 to 15 mm.<ref name="Ahti 2000"/>
True scyphi are goblet-like structures that are closed or rarely secondarily perforated at the bottom. They usually produce numerous conidiomata along their margins and, later, apothecia or hymenial disks. Scyphi may also produce vegetative secondary branchlets from their margins or centers.<ref name="Ahti 2000"/>
Verticillate podetia feature centrally proliferating scyphi forming conspicuous configurations characteristic of many species in ''Cladonia'' sect. ''Cladonia''. Funnels, or open cups, are trumpet-like structures with a central opening at the tip or axis of the podetium.<ref name="Ahti 2000"/>
==Taxonomic significance==
The configurations of podetia are highly variable, ranging from simple unbranched to complex, densely branched patterns, offering many useful taxonomic characters. Several branching patterns are recognized in ''Cladonia'':<ref name="Ahti 2000"/>
:*Dichotomous branching: One, two, three, or many branches produced from the same place :*Isotomous branching: Branches equal in length and thickness :*Anisotomous branching: Branches unequal in length and thickness
In ''Cladonia'', "regular" branching patterns have been recognized, although in boreal species, regular branching correlates with seasonal climates. Species of ''Cladina'' normally ramify once a year, following a dominant pattern such as anisotomic trichotomy or isototomic tetrachotomy.<ref name="Ahti 2000" />
The axis of the branching podetia is taxonomically useful. Open axils are perforated, either from the production of the first branches or in later development. Primary perforations differ from secondary ones that are mechanically produced by irregular growth.<ref name="Ahti 2000" />
==References== <references>
<ref name="Ahti 2000">{{cite book |author-link=Teuvo Ahti |last=Ahti |first=Teuvo |year=2000 |title=Cladoniaceae |series=Flora Neotropic Monograph |volume=78 |location=Bronx, New York |publisher=New York Botanical Garden Press |isbn=978-0-89327-431-3 |pages=9–12}}</ref>
</references>
Category:Fungal morphology and anatomy