Nemexia
Encyclopedia
Smilax sect. Nemexia is a section
of plant
s in the family Smilacaceae
. It consists of the herbaceous
plants within the genus Smilax
. Smilax species fall into two groups with distinctive morphologies: one group has woody perennial
stems with thorns and a vining habit, while the other group has herbaceous stems that die back to the ground each winter. S. sect. Nemexia is the taxon
that comprises the herbaceous species. In the past it was often a genus of its own under the name Nemexia and taxonomists still need further study of the species of Smilax to determine its proper rank. However the widely accepted taxonomic
system of the Flora of North America
does not recognize Nemexia, nor does the AP-site. Thus Nemexia is not currently considered an accepted genus taxon
by most plant taxonomists.
The plants in Smilax, are called carrion flower
s for their malodorous flower
s and those plants included in section Nemexia also have flowers that smell like rotten meat. The herbaceous species have greenish-yellow flowers and bloom in spring, they are fly
pollinated.
trnL-F and rpl16 sequences and the nuclear internal transcribed spacer
. The eastern North American species in the morphologically variable S. herbacea complex form a sister group to the western North American S. jamesii. The analysis did not conclusively clarify whether the S. herbacea complex should be recognized as different species. The two East Asian species, S. riparia and S. nipponica, formed two well-defined clades. It is hypothesized that the ancestor of this section evolved in Asia and spread to North America via the Bering Strait land bridge.
The current entry states "The two East Asian species, S. riparia and S. nipponica, formed two well-defined clades." But according to the abstract of reference 2 (Fu et al. 2005) "Results strongly support a clade of two well-defined East Asian species, Smilax riparia and S. nipponica." Thus, the entry should read:
"The two East Asian species, S. riparia and S. nipponica, formed a clade."
Section (botany)
In botany, a section is a taxonomic rank below the genus, but above the species. The subgenus, if present, is higher than the section, and the rank of series, if present, is below the section. Sections are typically used to help organise very large genera, which may have hundreds of species...
of plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s in the family Smilacaceae
Smilacaceae
Smilacaceae, the greenbrier family, is a family of flowering plants. Up to some decades ago the genera now included in family Smilacaceae were often assigned to a more broadly defined family Liliaceae, but for the past twenty to thirty years most botanists have accepted Smilacaceae as a distinct...
. It consists of the herbaceous
Herbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
plants within the genus Smilax
Smilax
Smilax is a genus of about 300-350 species, found in temperate zones, tropics and subtropics worldwide. In China for example about 80 are found , while there are 20 in North America north of Mexico...
. Smilax species fall into two groups with distinctive morphologies: one group has woody perennial
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
stems with thorns and a vining habit, while the other group has herbaceous stems that die back to the ground each winter. S. sect. Nemexia is the taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
that comprises the herbaceous species. In the past it was often a genus of its own under the name Nemexia and taxonomists still need further study of the species of Smilax to determine its proper rank. However the widely accepted taxonomic
Alpha taxonomy
Alpha taxonomy is the discipline concerned with finding, describing and naming species of living or fossil organisms. This field is supported by institutions holding collections of these organisms, with relevant data, carefully curated: such institutes include natural history museums, herbaria and...
system of the Flora of North America
Flora of North America
The Flora of North America North of Mexico is a multivolume work describing the native plants of North America. These days much of the Flora is available . The work is expected to fill 30 volumes when completed...
does not recognize Nemexia, nor does the AP-site. Thus Nemexia is not currently considered an accepted genus taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
by most plant taxonomists.
The plants in Smilax, are called carrion flower
Carrion flower
Carrion flowers or stinking flowers are flowers that emit an odor that smells like rotting flesh. Carrion flowers attract mostly scavenging flies and beetles as pollinators. Some species may trap the insects temporarily to ensure the gathering and transfer of pollen.- Amorphophallus :Many plants in...
s for their malodorous flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s and those plants included in section Nemexia also have flowers that smell like rotten meat. The herbaceous species have greenish-yellow flowers and bloom in spring, they are fly
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
pollinated.
Phylogenetic relationships
Cladistic analysis among several members of the section was carried out in 2005 on several gene sequences, including the plastidPlastid
Plastids are major organelles found in the cells of plants and algae. Plastids are the site of manufacture and storage of important chemical compounds used by the cell...
trnL-F and rpl16 sequences and the nuclear internal transcribed spacer
Internal transcribed spacer
ITS refers to a piece of non-functional RNA situated between structural ribosomal RNAs on a common precursor transcript. Read from 5' to 3', this polycistronic rRNA precursor transcript contains the 5' external transcribed sequence , 18S rRNA, ITS1, 5.8S rRNA, ITS2, 28S rRNA and finally the 3'ETS...
. The eastern North American species in the morphologically variable S. herbacea complex form a sister group to the western North American S. jamesii. The analysis did not conclusively clarify whether the S. herbacea complex should be recognized as different species. The two East Asian species, S. riparia and S. nipponica, formed two well-defined clades. It is hypothesized that the ancestor of this section evolved in Asia and spread to North America via the Bering Strait land bridge.
External links
- Smilacaceae in L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, information retrieval. Version: 9th March 2006. http://delta-intkey.com.
- Smilacaceae in Flora of North America
- links at CSDL, Texas
The current entry states "The two East Asian species, S. riparia and S. nipponica, formed two well-defined clades." But according to the abstract of reference 2 (Fu et al. 2005) "Results strongly support a clade of two well-defined East Asian species, Smilax riparia and S. nipponica." Thus, the entry should read:
"The two East Asian species, S. riparia and S. nipponica, formed a clade."