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''Phyllosiphon'' is a
Unusually among the green algae, members of ''Phyllosiphon'' are often parasitic within the leaves of
The species '' Phyllosiphon arisari'' Kühn induces necrosis in leaf tissue of '' Arisarum'', after invading the intracellular space. Another species, ''Phyllosiphon ari'', parasitizes leaves of ''Arum italicum''. Five additional species have been described from the tropics, but have not been reported since.
When free-living, ''Phyllosiphon'' species inhabit a variety of terrestrial habitats, in particular subaerial
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of green algae
The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...
in the class Trebouxiophyceae
The Trebouxiophyceae, also known as trebouxiophytes, are a class of green algae, in the division Chlorophyta. Members of this class are single-celled, colonial, or multicellular and are found in freshwater, terrestrial or marine habitats worldwid ...
.Round, F. E. (1981). ''The Ecology of Algae''. London: Cambridge University Press. pp. 398-400Unusually among the green algae, members of ''Phyllosiphon'' are often parasitic within the leaves of
Araceae
The Araceae are a family of monocotyledonous flowering plants in which flowers are borne on a type of inflorescence called a spadix. The spadix is usually accompanied by, and sometimes partially enclosed in, a spathe (or leaf-like bract). Also ...
, causing necrosis. It has a mostly tropical
The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...
to subtropical distribution, and is found primarily in the Mediterranean region, but has also been isolated in North America, Australia, Africa, and China.
Description
Most members of ''Phyllosiphon'' are parasitic green algae that inhabit the leaves of plants in the familyAraceae
The Araceae are a family of monocotyledonous flowering plants in which flowers are borne on a type of inflorescence called a spadix. The spadix is usually accompanied by, and sometimes partially enclosed in, a spathe (or leaf-like bract). Also ...
. When inside the leaves, they cause yellowish-green spots; they remain greenish in color even when the leaf dries. Microscopically, the thallus of ''Phyllosiphon'' consists of branched, siphonal filaments which penetrate the space between leaf parenchyma
upright=1.6, Lung parenchyma showing damage due to large subpleural bullae.
Parenchyma () is the bulk of functional substance in an animal organ such as the brain or lungs, or a structure such as a tumour. In zoology, it is the tissue that ...
cells. Asexual reproduction
Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the f ...
occurs from the formation of endospores, which fill the filaments. Endospores are about 3-6 μm in diameter and ellipsoidal.
A number of species of ''Phyllosiphon'' are free-living, but are phylogenetically
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...
in the same clade
In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
as parasitic ''Phyllosiphon'' species, and are therefore placed in the genus. When free-living, the cells are solitary and coccoid. Cells contain a single parietal, lobed chloroplast
A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...
with or without pyrenoid
Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''An ...
s, as well as oil droplets and carbohydrates.
Ecology
The species '' Phyllosiphon arisari'' Kühn induces necrosis in leaf tissue of '' Arisarum'', after invading the intracellular space. Another species, ''Phyllosiphon ari'', parasitizes leaves of ''Arum italicum''. Five additional species have been described from the tropics, but have not been reported since.
When free-living, ''Phyllosiphon'' species inhabit a variety of terrestrial habitats, in particular subaerial biofilm
A biofilm is a Syntrophy, syntrophic Microbial consortium, community of microorganisms in which cell (biology), cells cell adhesion, stick to each other and often also to a surface. These adherent cells become embedded within a slimy ext ...
s on tree bark.
References
Trebouxiophyceae genera Trebouxiophyceae {{green algae-stub