Potamogeton clystocarpus
Encyclopedia
Potamogeton clystocarpus is a rare species of flowering plant in the pondweed family
known by the common name Little Aguja pondweed. It is endemic to Texas
in the United States, where it is known only from one river canyon in Jeff Davis County
. There is a single population of the aquatic plant
in Little Aguja Creek, and it has never been seen anywhere else. This is a federally listed endangered species
of the United States.
This aquatic plant has a stem growing up to 57 centimeters long, varying in length depending on the depth of the water. The delicate, spirally arranged leaves are linear in shape and up to 7.8 centimeters in length by 1 or 2 millimeters wide. The inflorescence
is the only part of the plant that is not submersed. It arises a few centimeters above the water's surface. The plant reproduces sexually
via seed and vegetatively
via broken-off fragments of the stem, which can produce roots and anchor to form a new plant. Little else is known about the plant's life history
.
The plant has been noted and collected several times since its first collection in 1931. Though extremely restricted in distribution, it has usually appeared common to abundant in the one stream where it occurs. The Little Aguja Creek drains the Davis Mountains
of West Texas
. It is a very dynamic river, experiencing low levels during drought
, severe, scouring flood
ing during high-drainage seasons, and changing water quality
from chemical contamination and livestock
upriver.
In 1991 and 1992 heavy flooding scoured the canyon and the plant has not been seen since. Surveys have not relocated the plant.
Potamogetonaceae
The Potamogetonaceae, commonly referred to as the pondweed family, is an aquatic family of monocotyledonous flowering plants. There are roughly 120 species spread across six genera in the Potamagetonaceae...
known by the common name Little Aguja pondweed. It is endemic to Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
in the United States, where it is known only from one river canyon in Jeff Davis County
Jeff Davis County, Texas
Jeff Davis County is a county in the U.S. state of Texas. It is named for Jefferson Davis, the president of the Confederate States of America. It is one of the nine counties that comprise the Trans-Pecos region of West Texas. In 2000, its population was 2,207, and 2,258 by 2009...
. There is a single population of the aquatic plant
Aquatic plant
Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...
in Little Aguja Creek, and it has never been seen anywhere else. This 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...
of the United States.
This aquatic plant has a stem growing up to 57 centimeters long, varying in length depending on the depth of the water. The delicate, spirally arranged leaves are linear in shape and up to 7.8 centimeters in length by 1 or 2 millimeters wide. 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 the only part of the plant that is not submersed. It arises a few centimeters above the water's surface. The plant reproduces sexually
Sexual reproduction
Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
via seed and 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...
via broken-off fragments of the stem, which can produce roots and anchor to form a new plant. Little else is known about the plant's life history
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
.
The plant has been noted and collected several times since its first collection in 1931. Though extremely restricted in distribution, it has usually appeared common to abundant in the one stream where it occurs. The Little Aguja Creek drains the Davis Mountains
Davis Mountains
The Davis Mountains are a range of mountains in West Texas, located near Fort Davis, after which they are named. They are a popular site for camping and hiking and the region includes Fort Davis National Historic Site and Davis Mountains State Park...
of West Texas
West Texas
West Texas is a vernacular term applied to a region in the southwestern quadrant of the United States that primarily encompasses the arid and semi-arid lands in the western portion of the state of Texas....
. It is a very dynamic river, experiencing low levels during drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
, severe, scouring flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
ing during high-drainage seasons, and changing water quality
Water quality
Water quality is the physical, chemical and biological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose. It is most frequently used by reference to a set of standards against which...
from chemical contamination and livestock
Livestock
Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...
upriver.
In 1991 and 1992 heavy flooding scoured the canyon and the plant has not been seen since. Surveys have not relocated the plant.