Boechera hoffmannii
Encyclopedia
Boechera hoffmannii is a rare species of flowering plant in the mustard family
known by the common name Hoffmann's rockcress. It is endemic to the Channel Islands of California
, where it is known from only three or four populations on two of the eight islands. A 2005 report estimated a remaining global population of 244 individual plants. It is a federally listed endangered species
.
This is a perennial herb producing one or more erect stems from a scaly, hairy caudex
. The stems reach a maximum height between 50 and 70 centimeters and branch near the top. Leaves are densely clustered around the caudex in a basal rosette. They are lance-shaped, leathery with hairy undersides, and up to 10 centimeters long. There are more widely-spaced leaves along the stem which are 3 to 6 centimeters long. The inflorescence
bears many white or purple flowers with thick, dark sepal
s. The fruit is a tough, hairless silique
up to 10 centimeters long containing 2 rows of seeds.
The main threats to the existence of this rare plant are grazing and erosion caused by feral pigs and competition by invasive grasses
. The populations of this plant are also slow to reproduce. They are monocarpic
, with each individual living for a few years, fruiting once, and then dying, and each population has relatively few actively reproducing individuals in any given year.
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....
known by the common name Hoffmann's rockcress. It is endemic to the Channel Islands of California
Channel Islands of California
The Channel Islands of California are a chain of eight islands located in the Pacific Ocean off the coast of Southern California along the Santa Barbara Channel in the United States of America...
, where it is known from only three or four populations on two of the eight islands. A 2005 report estimated a remaining global population of 244 individual plants. It is a federally listed endangered species
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...
.
This is a perennial herb producing one or more erect stems from a scaly, hairy caudex
Caudex
A caudex is a form of stem morphology appearing as a thickened, short, perennial stem that is either underground or near ground level . It may be swollen for the purpose of water storage, especially in xerophytes...
. The stems reach a maximum height between 50 and 70 centimeters and branch near the top. Leaves are densely clustered around the caudex in a basal rosette. They are lance-shaped, leathery with hairy undersides, and up to 10 centimeters long. There are more widely-spaced leaves along the stem which are 3 to 6 centimeters long. The 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...
bears many white or purple flowers with thick, dark 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 fruit is a tough, hairless silique
Silique
A silique or siliqua is a fruit of 2 fused carpels with the length being more than three times the width. The outer walls of the ovary usually separate when ripe, leaving a persistent partition...
up to 10 centimeters long containing 2 rows of seeds.
The main threats to the existence of this rare plant are grazing and erosion caused by feral pigs and competition by invasive grasses
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
. The populations of this plant are also slow to reproduce. They are monocarpic
Monocarpic
Monocarpic plants are those that flower, set seeds and then die. Other terms with the same meaning are hapaxanth and semelparous. The term was first used by Alphonse de Candolle....
, with each individual living for a few years, fruiting once, and then dying, and each population has relatively few actively reproducing individuals in any given year.