''Rorippa subumbellata'' is a rare species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of ...

in the family

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 l ...

known by the common names Lake Tahoe yellowcress and Tahoe yellow cress. It is known only from the shores of

Lake Tahoe Lake Tahoe (; was, Dáʔaw, meaning "the lake") is a freshwater lake in the Sierra Nevada of the United States. Lying at , it straddles the state line between California and Nevada, west of Carson City. Lake Tahoe is the largest alpine lake ...

, straddling the border between

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

and

Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...

. There are an estimated fourteen populations of the plant still in existence.Center for Plant Conservation
/ref> It grows only on the direct shoreline of the lake, occupying a seven-foot semi-aquatic zone between the high- and low-tide marks. It is directly impacted by recreational activities on the lake, enduring bombardment by boat wakes, trampling, and construction of docks and other structures. This

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 medicina ...

produces spreading, branching, hairy stems up to 20 centimeters long. The leaves are 1 to 3 centimeters long, oblong or lance-shaped, and wavy along the edges or divided into lobes. 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 ...

is a compact

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 sh ...

of mustardlike flowers with yellow petals each about 3 millimeters long. The fruit is a hairless

silique A silique or siliqua (plural ''siliques'' or ''siliquae'') is a type of fruit (seed capsule) having two fused carpels with the length being more than three times the width. When the length is less than three times the width of the dried fruit ...

a few millimeters wide containing tiny seeds. The population sizes change with the lake's water level, with populations growing largest as water levels drop, exposing more sand habitat.The Nature Conservancy
/ref> High water levels may be beneficial at times, however, since they kill off competing plant species growing on the beaches. Restoration of this species has been hampered by low seed germination, but recent research has reduced this problem.

References

External links

Jepson Manual TreatmentUSDA Plants ProfileFlora of North AmericaPhoto gallery
subumbellata Critically endangered flora of California Flora of Nevada Flora of the Sierra Nevada (United States) {{Brassicales-stub