Frondosity (from Latin ''frondōsus'' meaning 'leafy') is the property of an organism that normally flourishes with fronds or leaf-like structures. Many frondose organisms are thalloid and lack the organization of tissues into organs, with the exception of ferns. Frondosity is significant mainly for distinguishing particular types of macroscopic algae, and in

paleobotany Paleobotany, which is also spelled as palaeobotany, is the branch of botany dealing with the recovery and identification of plant remains from geological contexts, and their use for the biological reconstruction of past environments (paleogeogr ...

and paleontology, by analyzing features present in fossil biota. Frondose macroalgae are relevant to the ecology of many marine and coastal ecosystems. Large frondose algae play an important role in the creation and functioning of healthy ecosystems from kelp forests to similar habitats. Yet, in

coral reefs A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of Colony (biology), colonies of coral polyp (zoology), polyps held together by calcium carbonate. Most coral reefs are built from stony corals, wh ...

, frondose seaweed can be recognized as harmful due to the link between excessive blooms and coastal eutrophication.

Ediacaran biota

The fossil record from the Ediacaran Period is sparse, as more easily fossilized hard-shelled animals had yet to evolve. Most fossils of the time are only faint impressions, and the shapes of fronds are one of the few identifying traits available. Frondose fossils are the longest studied of any Ediacaran remains, but, despite this, their affinities and biology are amongst the most controversial, ranging from animal to protist to plant or stem fungi. The oldest members of the

Ediacaran biota The Ediacaran (; formerly Vendian) biota is a Taxonomy (biology), taxonomic period classification that consists of all life forms that were present on Earth during the Ediacaran Period (). These were composed of enigmatic tubular and frond-sh ...

include discoid (disk-shaped) and frondose forms. Discoidal fossils had been classified as

cnidarian Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that th ...

medusae before being redefined as holdfasts of frondose organisms, that is, the roots or stalks that held them to the sea bed.

Rangeomorphs The rangeomorphs are a form taxon of frondose Ediacaran fossils that are united by a similarity to ''Rangea''. Some researchers, such as Pflug and Narbonne, suggest that a natural taxon Rangeomorpha may include all similar-looking fossils. Ra ...

consist of branching "frond" elements, each a few centimeters long, each of which is itself composed of many smaller branching tubes held up by a semi-rigid organic skeleton. This self-similar structure proceeds over four levels of

fractal In mathematics, a fractal is a geometric shape containing detailed structure at arbitrarily small scales, usually having a fractal dimension strictly exceeding the topological dimension. Many fractals appear similar at various scales, as illu ...

ity, and could have been formed using fairly simple developmental patterns. Rangeomorphs were radially symmetrical and likely sessile.

Bryozoans

Bryozoans, marine invertebrates, grow in colonial structures. The patterns of growth may be used for identification. One of the identifiable forms of bryozoan colonies, is frondose. Frondose colonies are erect and have branches that are flattened like leaves. These frond-bearing bryozoans existed in both ancient and modern times. Large tree-like forms flourished in the Triassic and Cretaceous, although frondose forms saw a decline in the Jurassic. A notable modern bryozoan with seaweed-like fronds is ''

Flustra foliacea ''Flustra foliacea'' is a species of bryozoans found in the northern Atlantic Ocean. It is a colonial animal that is frequently mistaken for a seaweed. Colonies begin as encrusting mats, and only produce loose fronds after their first year of g ...

''.

References

Botany Plant morphology Animal morphology {{Biology-stub