''Pediocactus knowltonii'' is a rare species of

cactus A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...

known by the common names Knowlton's miniature cactus, Knowlton's pincushion cactus, and Knowlton's minute cactus.

Distribution and habitat

It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

San Juan County, New Mexico San Juan County is located in the U.S. state of New Mexico. As of the 2020 census, the population was 121,661 making it the fifth-most populous county in New Mexico. Its county seat is Aztec. The county was created in 1887. San Juan County ...

, in the United States.USFWS
''Pediocactus knowltonii'' Five-year Review.
February 2010. The plant is only confirmed to exist in one New Mexico county, where there is a single population on a patch of territory measuring about . As of 2008, there are approximately 6100 individuals in this population. The cactus occurs on land very close to the

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...

border; in fact, it has been observed within of the state border, but it does not technically occur within the state of Colorado. Its habitat is pinyon-juniper woodland and sagebrush with

loam Loam (in geology and soil science) is soil composed mostly of sand (particle size > ), silt (particle size > ), and a smaller amount of clay (particle size < ). By weight, its mineral composition is about 40–40–20% concentration of sand–sil ...

gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...

alluvial Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluv ...

soils. In some areas the substrate is covered in

cobbles Cobblestone is a natural building material based on cobble-sized stones, and is used for pavement roads, streets, and buildings. Setts, also called Belgian blocks, are often casually referred to as "cobbles", although a sett is distinct fro ...

. The cactus may grow in the open or in the shade of larger plants.

Conservation

It is the smallest and rarest species in genus ''

Pediocactus ''Pediocactus'' (Greek: πεδίον (pedion) means "plain", "flat", "field") is a genus of cacti. The genus comprises between 6 and 11 species, depending upon the authority. Species of this genus are referred to as hedgehog cacti, though that ...

''.''Pediocactus knowltonii''.
Flora of North America. It is threatened by a number of human activities.''Pediocactus knowltonii''.
The Nature Conservancy. It is federally listed as an

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. The population is partly fenced and protected by

The Nature Conservancy The Nature Conservancy (TNC) is a global environmental organization headquartered in Arlington, Virginia. it works via affiliates or branches in 79 countries and territories, as well as across every state in the US. Founded in 1951, The Natu ...

Threats

The plant was discovered in 1958. It was immediately sought by collectors of cacti and within 20 years the population had been severely reduced. There may have been 100,000 individuals around the time it was discovered, and this number had been reduced to about 1000 by 1978. It is still a desirable specimen for cactus collectors because of its tiny size and rarity. The seed is available via the internet for about $10 per 100 seeds. Other threats include

off-road vehicle An off-road vehicle, sometimes referred to as an overland or adventure vehicle, is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with dee ...

use and development near the population.

Petroleum exploration Hydrocarbon exploration (or oil and gas exploration) is the search by petroleum geologists and geophysicists for deposits of hydrocarbons, particularly petroleum and natural gas, in the Earth#Crust, Earth using petroleum geology. Exploration m ...

activities are common in the area. Livestock graze nearby.

Drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

may reduce the population. Rodents, especially

mice A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

, eagerly consume the fruits, causing seed production to be low.

Description

A tiny cactus, it may reach a maximum size of 55 millimeters tall by 30 mm wide. It is often smaller, growing to the size of a US

penny A penny is a coin ( pennies) or a unit of currency (pl. pence) in various countries. Borrowed from the Carolingian denarius (hence its former abbreviation d.), it is usually the smallest denomination within a currency system. Presently, it is t ...

.''Pediocactus knowltonii''.
Center for Plant Conservation. An individual is considered to be an adult when it exceeds 10 mm in diameter. It is spherical or somewhat cylindrical in shape. The

areole In botany, areoles are small light- to dark-colored bumps on cacti out of which grow clusters of spines. Areoles are important diagnostic features of cacti, and identify them as a family distinct from other succulent plants. Gordon Rowley - W ...

s are round and covered in hairs. Each areole has up to 26 radial spines which are red, pink, or white in color. The spines are less than 2 mm long. The plant produces a flower up to 35 mm long by 25 mm wide with pinkish

tepal A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very ...

s, the outer ones sporting brownish midstripes. The fruit is green, ripening reddish, and measures about 4 mm long. According to a

genetic analysis Genetic analysis is the overall process of studying and researching in fields of science that involve genetics and molecular biology. There are a number of applications that are developed from this research, and these are also considered parts of ...

, this species probably evolved as a

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mi ...

of the larger ''

Pediocactus simpsonii ''Pediocactus'' (Greek: πεδίον (pedion) means "plain", "flat", "field") is a genus of cacti. The genus comprises between 6 and 11 species, depending upon the authority. Species of this genus are referred to as hedgehog cacti, though that ...

''.

References

External links

*
USDA Plants ProfilePhoto gallery
{{Taxonbar, from=Q150706 Cacti of the United States Flora of New Mexico Endemic flora of the United States Natural history of San Juan County, New Mexico knowltonii