Streptanthus niger
Encyclopedia
Streptanthus niger is an endangered species
within the family Brassicaceae
. Like other genus members, this herb
has wavy petal
margins with perimeter callus
es that discourage larva
l herbivory
. This plant is endemic
to the Tiburon Peninsula
of Northern California
, and occurs at elevations below 150 meters on serpentine grassland
s. The common name for this species is Tiburon Jewelflower or Black Jewelflower. This annual herb blooms in May and June and displays dark purple sepal
s. The etymology
of this genus scientific name derives from the Greek
word streptanthus, meaning twisted flower, with reference to the notable wavy margins of the petals. The species name niger relates to the color of the seed
s being black, although an alternate account cites the dark color of the petals as the source of the appellation.
herb
attaining a height of 20 to 70 centimeters. The plant architecture may manifest as simple-stemmed or branching in the upper part. Lower portions of the stems are smooth and practically hairless. This self-pollinated
plant has dark purple, almost black, flower petals; moreover, the petals have a purple claw and a white blade with a purple midvein. The zig-zag inflorescence
pattern is an identifying characteristic; furthermore, the flower is almost closed at its throat. Sepals measure five to seven millimeters. The characteristic wavy petal margins have calluses that inhibit larval herbivory. The leaves of S. niger appear in a basal
manifestation and measure less than nine centimeters in length; leaves are generally oblanceolate in shape, and may appear as coarsely dentate or short-lobed. Chromosomal
characterization is 2n=28.
(Streptanthus glandulosus).
s above shallow serpentine soil
s involving gentle to moderate southwestern facing slopes. The listing statement further notes that: "Serpentine soils are derived from ultramafic rocks such as serpentinite
, dunite
, and peridotite
, which are found in discontinuous outcrop
s in the...Coast Ranges". According to the Sacramento Fish and Wildlife Service: "species such as Tiburon jewelflower have adapted to serpentine soils and require them to survive".
. For each of the two known colonies, the population has varied between 25 and 2000 over recent years, indicating the precariousness of the species. The California Native Plant Society has placed S. niger on List 1B (rare or endangered throughout its range).
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
within the family Brassicaceae
Brassicaceae
Brassicaceae, a medium sized and economically important family of flowering plants , are informally known as the mustards, mustard flowers, the crucifers or the cabbage family....
. Like other genus members, this herb
Herbaceous plant
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...
has wavy petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals lying...
margins with perimeter callus
Callus (cell biology)
Plant callus is a mass of undifferentiated cells derived from plant tissue for use in biological research and biotechnology. In plant biology, callus cells are those cells that cover a plant wound. To induce callus formation, plant tissues are surface sterilized and then plated onto in vitro...
es that discourage larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
l herbivory
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
. This plant is endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...
to the Tiburon Peninsula
Tiburon, California
Tiburon is an incorporated town in Marin County, California. It occupies most of the Tiburon Peninsula, which reaches south into the San Francisco Bay. The smaller city of Belvedere occupies the south-east part of the peninsula and is contiguous with Tiburon...
of Northern California
Northern California
Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...
, and occurs at elevations below 150 meters on serpentine grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
s. The common name for this species is Tiburon Jewelflower or Black Jewelflower. This annual herb blooms in May and June and displays dark purple sepal
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...
s. The etymology
Etymology
Etymology is the study of the history of words, their origins, and how their form and meaning have changed over time.For languages with a long written history, etymologists make use of texts in these languages and texts about the languages to gather knowledge about how words were used during...
of this genus scientific name derives from the Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
word streptanthus, meaning twisted flower, with reference to the notable wavy margins of the petals. The species name niger relates to the color of the seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s being black, although an alternate account cites the dark color of the petals as the source of the appellation.
Description
Streptanthus niger is an annualAnnual plant
An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...
herb
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...
attaining a height of 20 to 70 centimeters. The plant architecture may manifest as simple-stemmed or branching in the upper part. Lower portions of the stems are smooth and practically hairless. This self-pollinated
Self-pollination
Self-pollination is a form of pollination that can occur when a flower has both stamen and a carpel in which the cultivar or species is self fertile and the stamens and the sticky stigma of the carpel contact each other in order to accomplish pollination...
plant has dark purple, almost black, flower petals; moreover, the petals have a purple claw and a white blade with a purple midvein. The zig-zag inflorescence
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. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
pattern is an identifying characteristic; furthermore, the flower is almost closed at its throat. Sepals measure five to seven millimeters. The characteristic wavy petal margins have calluses that inhibit larval herbivory. The leaves of S. niger appear in a basal
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
manifestation and measure less than nine centimeters in length; leaves are generally oblanceolate in shape, and may appear as coarsely dentate or short-lobed. Chromosomal
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
characterization is 2n=28.
Taxonomy
This species is often considered a subspecies of the Bristly JewelflowerStreptanthus glandulosus
Streptanthus glandulosus is a species of flowering plant in the mustard family known by the common name bristly jewelflower. It is native to California and southwestern Oregon, where it grows in many types of habitat, including grassland, chaparral, and woodlands...
(Streptanthus glandulosus).
Distribution and habitat
There are only two known colonies of Tiburon Jewelflower, both of which occur on the Tiburon Peninsula, with a separation of about three kilometers. One of the populations is in the vicinity of the historic Old St. Hilary's Church. The Federal Register listing document noted that S. niger occurs only on grasslandGrassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
s above shallow serpentine soil
Serpentine soil
A serpentine soil is derived from ultramafic rocks, in particular serpentinite, a rock formed by the hydration and metamorphic transformation of ultramafic rock from the Earth's mantle....
s involving gentle to moderate southwestern facing slopes. The listing statement further notes that: "Serpentine soils are derived from ultramafic rocks such as serpentinite
Serpentinite
Serpentinite is a rock composed of one or more serpentine group minerals. Minerals in this group are formed by serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle...
, dunite
Dunite
Dunite is an igneous, plutonic rock, of ultramafic composition, with coarse-grained or phaneritic texture. The mineral assemblage is greater than 90% olivine, with minor amounts of other minerals such as pyroxene, chromite and pyrope. Dunite is the olivine-rich end-member of the peridotite group...
, and peridotite
Peridotite
A peridotite is a dense, coarse-grained igneous rock, consisting mostly of the minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium, reflecting the high proportions of magnesium-rich olivine, with appreciable iron...
, which are found in discontinuous outcrop
Outcrop
An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. -Features:Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be...
s in the...Coast Ranges". According to the Sacramento Fish and Wildlife Service: "species such as Tiburon jewelflower have adapted to serpentine soils and require them to survive".
Conservation
The Tiburon Jewelflower was first collected by Edward L. Greene in the year 1886 at the site of Old Saint Hilary's Church on the Tiburon Peninsula. Streptanthus niger was designated as endangered by the state of California in the year 1990 and listed by the U.S. federal government five years later. By 1998 a Species Recovery Plan had been prepared to provide more specific protection measures for this endangered dicotyledonDicotyledon
The dicotyledons, also known as dicots, are a group of flowering plants whose seed typically has two embryonic leaves or cotyledons. There are around 199,350 species within this group...
. For each of the two known colonies, the population has varied between 25 and 2000 over recent years, indicating the precariousness of the species. The California Native Plant Society has placed S. niger on List 1B (rare or endangered throughout its range).
External links
- Streptanthus niger, Tiburon jewelflower USDA PLANTS database
- Streptanthus niger, Tiburon Jewelflower Jepson Manual treatment