Brassicaceae
Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The leav ...
. Like other genus members, this herb has wavy petal margins with perimeter
callus
A callus is an area of thickened and sometimes hardened skin that forms as a response to repeated friction, pressure, or other irritation. Since repeated contact is required, calluses are most often found on the feet and hands, but they may o ...
es that discourage
larva
A larva (; plural larvae ) 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
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
. This plant is
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 else ...
to the
Tiburon Peninsula
The Tiburon Peninsula (french: Péninsule de Tiburon), or The Xaragua Peninsula, simply "the Tiburon" (''le Tiburon''), is a region of Haiti encompassing most of Haiti's southern coast.
It starts roughly at the southernmost point of the Haiti-D ...
grassland
A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...
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
A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coine ...
s. The
etymology
Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...
of this genus scientific name derives from the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
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
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
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
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 (band), ...
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
Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corolla''. Petals are usually ...
have a purple claw and a white blade with a purple midvein. The zig-zag
inflorescence
An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
pattern is an identifying characteristic; furthermore, the flower is almost closed at its throat. Sepals measure five to seven mm. The characteristic wavy petal margins have calluses that inhibit larval
herbivory
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
. 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
Dentate may refer to:
* A species having dentition
* An energy-dissipating baffle block in a spillway
* An individual not being edentulous
* Dentate gyrus of the hippocampus
* Dentate nucleus of the cerebellum
* Denticity in chemistry
* Dentat ...
or short-lobed.
Chromosomal
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
characterization is 2n=28. This plant is also known for belonging to the mustard family and producing black mustard seeds.
Taxonomy
This species is often considered a subspecies of the bristly jewelflower (''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 km. One of the populations is in the vicinity of the historic Old Saint Hilary's Church. The Federal Register listing document noted that ''S. niger'' occurs only on
grassland
A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...
s above shallow serpentine soils involving gentle to moderate southwestern facing slopes. The listing statement further notes that: "Serpentine soils are derived from
ultramafic
Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed ...
rocks such as
serpentinite
Serpentinite is a rock composed predominantly of one or more serpentine group minerals, the name originating from the similarity of the texture of the rock to that of the skin of a snake. Serpentinite has been called ''serpentine'' or ''se ...
,
dunite
Dunite (), also known as olivinite (not to be confused with the mineral olivenite), is an intrusive igneous rock of ultramafic composition and with phaneritic (coarse-grained) texture. The mineral assemblage is greater than 90% olivine, with ...
, and peridotite, which are found in discontinuous
outcrop
An outcrop or rocky 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 superficia ...
s in the...
Coast Ranges
The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Although th ...
". 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 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 dicotyledon. For each of the two known colonies, the population has varied between 25 and 2000 over recent years, indicating the precariousness of the species. An assistant professor from
Mills College
Mills College at Northeastern University is a private college in Oakland, California and part of Northeastern University's global university system. Mills College was founded as the Young Ladies Seminary in 1852 in Benicia, California; it was ...
, with financial support from the Marin Country Open Space District, is carrying out a three year research project on conservation of the species. The
California Native Plant Society
The California Native Plant Society (CNPS) is a California environmental non-profit organization (501(c)3) that seeks to increase understanding of California's native flora and to preserve it for future generations. The mission of CNPS is to con ...
has placed ''S. niger'' on List 1B (rare or endangered throughout its range).
Jepson Manual
''The Jepson Manual'' is a flora of the vascular plants that are either native to or naturalized in California. Botanists often refer to the book simply as ''Jepson''. It is produced by the University and Jepson Herbaria, of the University of C ...