Philcoxia
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''Philcoxia'' is a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of seven rare plant species in the
Plantaginaceae Plantaginaceae, the plantain family, is a large, diverse family of flowering plants in the order Lamiales that includes common flowers such as snapdragon and foxglove. It is unrelated to the banana-like fruit also called "plantain." In older cl ...
that are
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
to
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
and resemble terrestrial species of the genus ''
Utricularia ''Utricularia'', commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species (precise counts differ based on classification opinions; a 2001 publication lists 215 species).Salmon, Br ...
''. The genus, formally described in 2000, consists of the species '' P. bahiensis'', '' P. goiasensis'', '' P. minensis'', '' P. tuberosa'', '' P. rhizomatosa'', '' P. maranhensis'' and '' P. courensis'', each of the first three named for the Brazilian state to which it is endemic. The species are characterized by subterranean stems,
peltate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...
leaves at or below the soil surface, and five-lobed calyces. Their habitat has been reported as areas of white sand in the midst of
cerrado The ''Cerrado'' (, ) is a vast ecoregion of tropical savanna in eastern Brazil, particularly in the states of Goiás, Mato Grosso do Sul, Mato Grosso, Tocantins, Minas Gerais, and the Federal District. The core areas of the Cerrado biome are t ...
vegetation at an
elevation The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Vert ...
between 800 and 1450 m. Initial descriptions of the genus included suspicions that the plethora of stalked capitate glands on the upper surfaces of leaves was an indication that these species may be
carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...
. A study published in 2007 tested ''P. minensis'' for
protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...
activity, a typical test for the carnivorous syndrome, and could detect none. Later studies detected other digestive enzymes such as
phosphatase In biochemistry, a phosphatase is an enzyme that uses water to cleave a phosphoric acid Ester, monoester into a phosphate ion and an Alcohol (chemistry), alcohol. Because a phosphatase enzyme catalysis, catalyzes the hydrolysis of its Substrate ...
s and qualitatively assessed prey digestion and nutrient uptake, suggesting that it is a true carnivorous plant. The genus epithet honors David Philcox (1926-2003), a botanist at
Kew Gardens Kew Gardens is a botanical garden, botanic garden in southwest London that houses the "largest and most diverse botany, botanical and mycology, mycological collections in the world". Founded in 1840, from the exotic garden at Kew Park, its li ...
who worked extensively in tropical
Scrophulariaceae The Scrophulariaceae are a family of flowering plants, commonly known as the figwort family. The plants are annual and perennial herbs, as well as shrubs. Flowers have bilateral (zygomorphic) or rarely radial (actinomorphic) symmetry. The Scr ...
.Fritsch, P.W., Almeda, F., Martins, A.B., Cruz, B.C., and Estes, D. (2007)
Rediscovery and phylogenetic placement of ''Philcoxia minensis'' (Plantaginaceae), with a test of carnivory.
''Proceedings of the California Academy of Sciences'', Fourth Series, 58(21): 447-467.
Taylor, P., Souza, V.C., Giulietti, A.M., and Harley, R.M. (2000). ''Philcoxia'': A new genus of Scrophulariaceae with three new species from Eastern Brazil. ''Kew Bulletin'', 55(1): 155-163.


Description

Members of the genus are small
perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
or
annual Annual may refer to: * Annual publication, periodical publications appearing regularly once per year **Yearbook ** Literary annual * Annual plant * Annual report * Annual giving * Annual, Morocco, a settlement in northeastern Morocco * Annuals (b ...
herbs that reside in oases of deep white sand surrounded by the typical vegetation of the
cerrado The ''Cerrado'' (, ) is a vast ecoregion of tropical savanna in eastern Brazil, particularly in the states of Goiás, Mato Grosso do Sul, Mato Grosso, Tocantins, Minas Gerais, and the Federal District. The core areas of the Cerrado biome are t ...
ecoregion. They are no more than 26 cm tall with 5-10 leaves. Zigzag-shaped
raceme A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...
s are produced from upright stems and account for the height of the species. These monotelic
inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...
s are leafless and produce pale blue to lilac flowers (''P. goiasensis'' has a yellow corolla tube). The flowers possess monothecous, glabrous anthers, which are unusual in the family. The upper surface of the leaves are covered with stalked capitate glands that are also seen in many carnivorous plant genera.


Taxonomy

The nature of ''Philcoxias highly specialized morphology has led to confusion about its proper taxonomic placement. In 1996, before ''Philcoxia'' was even formally published as a taxon, it had been placed by Vinícius Souza in the
tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English language, English is in the discipline of anthropology. This definition is contested, in p ...
Scrophularieae of the
Scrophulariaceae The Scrophulariaceae are a family of flowering plants, commonly known as the figwort family. The plants are annual and perennial herbs, as well as shrubs. Flowers have bilateral (zygomorphic) or rarely radial (actinomorphic) symmetry. The Scr ...
.
Peter Taylor Peter Taylor may refer to: Arts * Peter Taylor (writer) (1917–1994), American author, winner of the Pulitzer Prize for Fiction * Peter Taylor (film editor) (1922–1997), English film editor, winner of an Academy Award for Film Editing Politic ...
''et al.'' later noted in the 2000 description of the genus that its affinities should include the genera ''
Gratiola ''Gratiola'' is a genus of plants in the family Plantaginaceae. Most species are known generally as hedgehyssops. The genus was previously included in the family Scrophulariaceae. Species include: *'' Gratiola amphiantha'' - pool sprite, snorkel ...
'' and '' Dopatrium'' in the tribe Gratioleae of the Scrophulariaceae. The
Angiosperm Phylogeny Group The Angiosperm Phylogeny Group (APG) is an informal international group of systematic botanists who collaborate to establish a consensus on the taxonomy of flowering plants (angiosperms) that reflects new knowledge about plant relationships disco ...
later changed the circumscription of the Scrophulariaceae so that the tribe Gratioleae is now within the
Plantaginaceae Plantaginaceae, the plantain family, is a large, diverse family of flowering plants in the order Lamiales that includes common flowers such as snapdragon and foxglove. It is unrelated to the banana-like fruit also called "plantain." In older cl ...
. In 2004, E. Fischer also placed in tribe Gratioleae, but also placed it within the informally recognized subtribe Dopatriinae, which was described as also containing the genera '' Deinostema'', '' Dopatrium'', '' Hydrotriche'', and '' Limnophila'', which consist mostly of aquatic species. In 2007, an extensive study and phylogenetic analysis by Peter Fritsch ''et al.'' confirmed that ''Philcoxia'' should be placed in the tribe Gratioleae, but it is in fact not as closely related to ''Gratiola'' and the Dopatriinae as was previously assumed. Recent research has suggested that ''P. minensis'' may be
polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of converg ...
, so may represent more than one species.


Botanical history

The first recognized specimens of ''Philcoxia'' (''P. bahiensis'') were collected by local resident Wilson Ganev in August 1992 from the Serra do Atalho in the municipality of Piatã of
Bahia Bahia ( , , ; meaning "bay") is one of the 26 Federative units of Brazil, states of Brazil, located in the Northeast Region, Brazil, Northeast Region of the country. It is the fourth-largest Brazilian state by population (after São Paulo (sta ...
. One collection was sent to
Kew Gardens Kew Gardens is a botanical garden, botanic garden in southwest London that houses the "largest and most diverse botany, botanical and mycology, mycological collections in the world". Founded in 1840, from the exotic garden at Kew Park, its li ...
for naming. Because of its
placentation Placentation refers to the formation, type and structure, or arrangement of the placenta. The function of placentation is to transfer nutrients, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to remove ...
, the specimen was determined to be a member of the Scrophulariaceae (later Plantaginaceae ''sensu''
APG II The APG II system (Angiosperm Phylogeny Group II system) of plant classification is the second, now obsolete, version of a modern, mostly molecular-based, system of plant taxonomy that was published in April 2003 by the Angiosperm Phylogeny Gr ...
) despite its appearance close to that of terrestrial ''
Utricularia ''Utricularia'', commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species (precise counts differ based on classification opinions; a 2001 publication lists 215 species).Salmon, Br ...
''. Material of this specimen had been sent to Vinícius Souza, who was working on the Scrophulariaceae of Brazil. Souza recognized the material as congeneric with a plant collected in 1981 from the Serra do Cabral of the Brazilian state
Minas Gerais Minas Gerais () is a state in Southeastern Brazil. It ranks as the second most populous, the third by gross domestic product (GDP), and the fourth largest by area in the country. The state's capital and largest city, Belo Horizonte (literally ...
. The collection was made by a group from the
University of São Paulo The University of São Paulo ( pt, Universidade de São Paulo, USP) is a public university in the Brazilian state of São Paulo. It is the largest Brazilian public university and the country's most prestigious educational institution, the best ...
. The site location of that collection was not identified and subsequent expeditions were unable to relocate the species until 2007. However, an even earlier specimen now recognized as ''P. goiasensis'' had been collected in 1966 near
Posse Posse is a shortened form of posse comitatus, a group of people summoned to assist law enforcement. The term is also used colloquially to mean a group of friends or associates. Posse may also refer to: Arts and entertainment * ''Posse'' (1975 ...
in the northeastern state of
Goiás Goiás () is a Brazilian state located in the Center-West region. Goiás borders the Federal District and the states of (from north clockwise) Tocantins, Bahia, Minas Gerais, Mato Grosso do Sul and Mato Grosso. The state capital is Goiânia. ...
by a group from the
New York Botanical Garden The New York Botanical Garden (NYBG) is a botanical garden at Bronx Park in the Bronx, New York City. Established in 1891, it is located on a site that contains a landscape with over one million living plants; the Enid A. Haupt Conservatory, ...
. Initially, the specimen had been determined to be a member of the
Lentibulariaceae Lentibulariaceae is a family of carnivorous plants containing three genera: ''Genlisea'', the corkscrew plants; ''Pinguicula'', the butterworts; and ''Utricularia'', the bladderworts. The genera ''Polypompholyx'' (two species of pink petticoats ...
. Peter Taylor and David Philcox later concluded that this represented an undescribed genus of Scrophulariaceae. A description and illustration was completed and set aside for over twenty years. Then, in 1994, Taylor showed the specimen and description to Ray Harley in preparation for publication. Harley, who had been involved in the early 1990s discovery of ''P. bahiensis'', recognized Taylor's materials as another species of the as yet undescribed genus.


Carnivory

Peter Taylor, in his 2000 description of the genus, suggested that the morphology ''Philcoxia'' resembles that of the carnivorous
Lentibulariaceae Lentibulariaceae is a family of carnivorous plants containing three genera: ''Genlisea'', the corkscrew plants; ''Pinguicula'', the butterworts; and ''Utricularia'', the bladderworts. The genera ''Polypompholyx'' (two species of pink petticoats ...
and the relatively unrelated
Droseraceae Droseraceae is a family (biology), family of carnivorous flowering plants, also known as the sundew family. It consists of approximately 180 species in three Extant taxon, extant genera. Representatives of the Droseraceae are found on all conti ...
in some aspects. The upper surface of the leaves are covered in stalked capitate glands similar to those seen in other
carnivorous plant Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryot ...
s. Taylor noted that field observations had not indicated that there was any carnivorous function of the leaves, citing a lack of captured prey as evidence. Peter Fritsch and his coauthors decided to do a more comprehensive test for carnivory on ''P. minensis'' after they observed
nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
worms on leaf surfaces. The similarity between the habitat for ''Philcoxia'' species and that of ''
Genlisea ''Genlisea'' ( ) is a genus of carnivorous plants also known as corkscrew plants. The 30 or so species grow in wet terrestrial to semi-aquatic environments distributed throughout Africa and Central and South America. The plants use highly modifi ...
'' and their similar subterranean leaves and stems spurred the team's decision to test for potential carnivory in the field and ''in situ''. They tested for a
protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...
enzyme that is one of the enzymes found in other carnivorous plants and is responsible for breaking down captured prey. They hypothesized that ''Philcoxia'' could be carnivorous, capturing nematodes and possibly soil microbes like ''
Utricularia ''Utricularia'', commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species (precise counts differ based on classification opinions; a 2001 publication lists 215 species).Salmon, Br ...
'' and ''
Genlisea ''Genlisea'' ( ) is a genus of carnivorous plants also known as corkscrew plants. The 30 or so species grow in wet terrestrial to semi-aquatic environments distributed throughout Africa and Central and South America. The plants use highly modifi ...
'' do. Ultimately, Fritsch's study concluded that while no protease activity was detected, this fact does not rule out the possibility that the genus may be carnivorous in some other way. They note that there are many possibilities, such as seasonal carnivory or the unusual growth form being an adaptation to the heat and sun, and more study is needed before precise conclusions can be reached. A study by Caio G. Pereira ''et al.'' published in 2012 provided experimental evidence using 15N-labeled nematodes, concluding that ''P. minensis'' actively digests prey and absorbs the nutrients. This data was combined with the observation that the leaf surfaces of ''P. minensis'' produce
phosphatase In biochemistry, a phosphatase is an enzyme that uses water to cleave a phosphoric acid Ester, monoester into a phosphate ion and an Alcohol (chemistry), alcohol. Because a phosphatase enzyme catalysis, catalyzes the hydrolysis of its Substrate ...
s, similar to many other carnivorous plants.Pereira, CG, DP Almenara, CE Winter, PW Fritsch, H Lambers, and RS Oliveira. 2012. Underground leaves of ''Philcoxia'' trap and digest nematodes. ''Proc. Natl. Acad. Sci. USA'', published online ahead of print. The similarity in structures in all the species of this genus suggest that all species are carnivorous.


References


External links


Plantaginaceae
at the
Angiosperm Phylogeny Website The Angiosperm Phylogeny Website (or APweb) is a website dedicated to research on angiosperm phylogeny and taxonomy. The site is hosted by the Missouri Botanical Garden website and maintained by researchers, Peter F. Stevens and Hilary M. Davis ...
. Version 8, June 2007. {{Taxonbar, from=Q145462 Flora of Brazil Plantaginaceae Plantaginaceae genera Carnivorous plants