Carex albida
Encyclopedia
Carex albida is a very rare species of sedge
known by the common name white sedge. It is endemic to Sonoma County, California
, where it is known only from one occurrence at Pitkin Marsh, a wetland
between Forestville
and Sebastopol
. There are fewer than 1000 plants remaining, and likely fewer than 300 according to more recent estimates. It is a federally listed endangered species
.
This sedge produces a dense or loose clump of erect stems 40 to 60 centimeters tall from a network of short rhizome
s. The inflorescence
is a cluster of 5 to 7 spikes over 15 centimeters long. Staminate
flowers are located mainly on the terminal spike, while pistillate
flowers are mainly located in the lateral spikes. The fruit is covered in a sac called a perigynium, which is green with a white beak.
The plant has been reduced to its current small population size by alterations in its wetland habitat, which resulted in the destruction of a few other known occurrences. Since it was added to the endangered species list, two new colonies of the plant have been discovered, but these are so close to the single previously known population that they do not count as new occurrences. The colonies are scattered across 5 acres (20,234.3 m²) of a 27 acres (109,265.2 m²) tract. As with other plants that reproduce vegetatively
by cloning
from their rhizome
s, the number of true separate individual life forms is hard to estimate, so researchers count visible stems; a recent count revealed fewer than 300, a decrease from nearly 1000.
This sedge occurs near another rare local endemic, the Pitkin Marsh lily
(Lilium pardalinum ssp. pitkinense).
Carex
Carex is a genus of plants in the family Cyperaceae, commonly known as sedges. Other members of the Cyperaceae family are also called sedges, however those of genus Carex may be called "true" sedges, and it is the most species-rich genus in the family. The study of Carex is known as...
known by the common name white sedge. It is endemic to Sonoma County, California
Sonoma County, California
Sonoma County, located on the northern coast of the U.S. state of California, is the largest and northernmost of the nine San Francisco Bay Area counties. Its population at the 2010 census was 483,878. Its largest city and county seat is Santa Rosa....
, where it is known only from one occurrence at Pitkin Marsh, a wetland
Marsh
In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....
between Forestville
Forestville, California
Forestville is a census-designated place in Sonoma County, California, United States. The town came into existence during the late 1860s and was originally named Forrestville, after one its founders, but the spelling long ago became standardized with one "r". The population was 3,293 at the 2010...
and Sebastopol
Sebastopol, California
Sebastopol is a city in Sonoma County, California, United States, approximately north of San Francisco. The population was 7,379 at the 2010 census, but its businesses also serve surrounding rural portions of Sonoma County, totaling about 50,000 people...
. There are fewer than 1000 plants remaining, and likely fewer than 300 according to more recent estimates. 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 sedge produces a dense or loose clump of erect stems 40 to 60 centimeters tall from a network of short rhizome
Rhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...
s. 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...
is a cluster of 5 to 7 spikes over 15 centimeters long. Staminate
Stamen
The stamen is the pollen producing reproductive organ of a flower...
flowers are located mainly on the terminal spike, while pistillate
Gynoecium
Gynoecium is most commonly used as a collective term for all carpels in a flower. A carpel is the ovule and seed producing reproductive organ in flowering plants. Carpels are derived from ovule-bearing leaves which evolved to form a closed structure containing the ovules...
flowers are mainly located in the lateral spikes. The fruit is covered in a sac called a perigynium, which is green with a white beak.
The plant has been reduced to its current small population size by alterations in its wetland habitat, which resulted in the destruction of a few other known occurrences. Since it was added to the endangered species list, two new colonies of the plant have been discovered, but these are so close to the single previously known population that they do not count as new occurrences. The colonies are scattered across 5 acres (20,234.3 m²) of a 27 acres (109,265.2 m²) tract. As with other plants that reproduce vegetatively
Vegetative reproduction
Vegetative reproduction is a form of asexual reproduction in plants. It is a process by which new individuals arise without production of seeds or spores...
by cloning
Cloning
Cloning in biology is the process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. Cloning in biotechnology refers to processes used to create copies of DNA fragments , cells , or...
from their rhizome
Rhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...
s, the number of true separate individual life forms is hard to estimate, so researchers count visible stems; a recent count revealed fewer than 300, a decrease from nearly 1000.
This sedge occurs near another rare local endemic, the Pitkin Marsh lily
Lilium pardalinum subsp. pitkinense
The Pitkin Marsh lily, or Lilium pardalinum subsp. pitkinense, is an endangered perennial herb of the Liliaceae family that is endemic to certain wetland areas in the California Coast Ranges of Sonoma County, California, USA. This subspecies of Lilium pardalinum attains a height of one to two...
(Lilium pardalinum ssp. pitkinense).