''Borodinia perstellata'', commonly known as Braun's rockcress and Nevada rockcress, is a rare species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the

mustard family 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 le ...

. It is native to

Kentucky Kentucky ( , ), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders Illinois, Indiana, and Ohio to the north; West Virginia and Virginia to ...

and

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

, where it is known from perhaps 25 total populations.Center for Plant Conservation
Most of the occurrences have few individuals, and all are deteriorating in quality.The Nature Conservancy
/ref> The plant grows in shady forest habitat on

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

substrates, usually near streams or rivers. This is a federally listed

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

of the United States.USFWS
Determination of endangered status for ''Arabis perstellata''.
''Federal Register'' January 3, 1995.

Description

This rockcress is a

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 ...

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...

with decumbent stems reaching 80 centimeters in length. The stems spread out horizontally, and often droop over the side of any structure the plant may be growing on, such as a rock or cliffside. The leaves are arranged in a basal rosette with some alternately arranged along the stem. The stems and leaves are gray-green in color due to a coating of whitish star-shaped hairs. The

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 ...

is a

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 ...

of flowers with four white or lavender petals each a few millimeters long. The fruit is a hairy silique 1.5 to 2 centimeters in length which contains tiny reddish seeds.

Habitat

Some authorities divide the species into two varieties, var. ''perstellata'' (small rockcress), which is mostly limited to Franklin County, Kentucky, in the vicinity of the

Kentucky River The Kentucky River is a tributary of the Ohio River, long,U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map , accessed June 13, 2011 in the Commonwealth (U.S. state), U.S. Commonwealth of Kentuc ...

, and var. ''ampla'' (large rockcress), which is known only from

. Other authorities do not divide the species and suggest any physical differences are caused by the local environment.

Conservation

While the plant is often found in disturbed habitat such as roadcuts, excessive disturbance is a threat to its existence. Forces such as development, erosion, and logging disrupt its habitat. Other threats include competition from non-native plants, including the

invasive Invasive may refer to: *Invasive (medical) procedure *Invasive species *Invasive observation, especially in reference to surveillance *Invasively progressive spread of disease from one organ in the body to another, especially in reference to cancer ...

garlic mustard ''Alliaria petiolata'', or garlic mustard, is a biennial flowering plant in the mustard family (Brassicaceae). It is native to Europe, western and central Asia, north-western Africa, Morocco, Iberia and the British Isles, north to northern Sc ...

(''Alliaria petiolata'') and

amur honeysuckle ''Lonicera maackii'', the Amur honeysuckle, is a species of honeysuckle in the family Caprifoliaceae that is native to temperate western Asia; specifically in northern and western China south to Yunnan, Mongolia, Primorsky Krai in southeastern S ...

(''Lonicera maackii'').USFWS
Designation of critical habitat for ''Arabis perstellata'' (Braun’s Rock-cress).
''Federal Register'' June 3, 2004.

References

External links

USDA Plants Profile
{{Taxonbar, from1=Q50840879, from2=Q4937076 perstellata Flora of Kentucky Flora of Tennessee Flora of Northern America