''Quercus opaca'' is a species of

evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...

shrub in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Quercus An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

''. It is native to northeastern and central

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

Description

''Quercus opaca'' typically does not exceed 2 meters in height, with an average height of around 1-1.5 metres. The

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

of ''Quercus opaca'' are evergreen. They are oblong,

lanceolate The following terms are used to describe leaf plant morphology, morphology in the description and taxonomy (biology), taxonomy of plants. Leaves may be simple (that is, the leaf blade or 'lamina' is undivided) or compound (that is, the leaf blade ...

to elliptic in shape, measuring approximately 2.5 to 4.5 centimetres in length and 1 to 1.5 centimetres in width. The leaf apex can be acute, obtuse, or rounded, often with a

mucronate The following terms are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (that is, the leaf blade or 'lamina' is undivided) or compound (that is, the leaf blade is divided into two or more leaflets) ...

tip. The base of the leaf is typically obtuse to cordate, sometimes rounded. The leaf margin is thickened and may appear flat or slightly rolled back. Most leaves are observed to be entire, although some may possess 1-3 pairs of sharp mucronate teeth near the apex. The adaxial surface has a

glaucous ''Glaucous'' (, ) is used to describe the pale grey or bluish-green appearance of the surfaces of some plants, as well as in the names of birds, such as the glaucous gull (''Larus hyperboreus''), glaucous-winged gull (''Larus glaucescens''), ...

appearance and appears dull. Small star-shaped hairs can be found at the base of the midvein. The abaxial surface is not lustrous and also appears glaucous. There are only a few sessile stellate

trichomes Trichomes (; ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...

and white glandular hairs that are mainly present on the midvein. The

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and Subcutaneous tissue, hypodermis. The epidermal layer provides a barrier to infection from environmental pathogens and regulates the ...

of the leaf is notably whitish papillose. The leaf veins consist of 6-10 pairs that are flat above and slightly raised beneath. The

petiole Petiole may refer to: *Petiole (botany), the stalk of a leaf, attaching the blade to the stem *Petiole (insect anatomy) In entomology, petiole is the technical term for the narrow waist of some hymenopteran insects, especially ants, bees, and ...

measures 3-7 millimeters in length and is

pubescent The adjective pubescent may describe: * people or animals undergoing puberty * plants that are hairy, covered in trichomes * insects that are covered in setae In biology, setae (; seta ; ) are any of a number of different bristle- or hair-lik ...

with a reddish-brown colour. ''Quercus opaca'' produces male

catkins A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated (as in ''Salix''). It contains many, usually unisexual flowers, arranged cl ...

that are 3-4 centimetres long and contain many flowers. ''Quercus opacas fruit is an

ovoid An oval () is a closed curve in a plane which resembles the outline of an egg. The term is not very specific, but in some areas of mathematics (projective geometry, technical drawing, etc.), it is given a more precise definition, which may inc ...

acorn The acorn is the nut (fruit), nut of the oaks and their close relatives (genera ''Quercus'', ''Notholithocarpus'' and ''Lithocarpus'', in the family Fagaceae). It usually contains a seedling surrounded by two cotyledons (seedling leaves), en ...

which measures around 9 millimetres long which is also

glabrous Glabrousness () is the technical term for a lack of hair, down, setae, trichomes, or other such covering. A glabrous surface may be a natural characteristic of all or part of a plant or animal, or be due to loss because of a physical condition, ...

. The acorn is partly enclosed by a cupule that is half-rounded and slightly

tomentose Trichomes (; ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...

. The acorns mature within the first year and are typically observed in September. They are solitary or appear in pairs on a

glabrescent Glabrousness () is the technical term for a lack of hair, down, setae, trichomes, or other such covering. A glabrous surface may be a natural characteristic of all or part of a plant or animal, or be due to loss because of a physical condition, ...

peduncle that is 0.5 centimetres long. The bark of ''Quercus opaca'' is grey and scaly in appearance. The twigs have a diameter of 1.5-2 millimeters and are

sulcate Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains ...

, waxy, and covered in short pubescence consisting of sessile multiradiate trichomes and

glandular A gland is a cell or an organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also function to remove unwanted substance ...

hairs. Over time, the twigs become

. The buds are

subglobose This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary ...

, measuring 1-2 millimetres in width, and have a brown color with pubescent scales along the margins. The

stipules In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). They are primarily found among dicots and rare among monocots. Stipules are considered part of the anatomy ...

are pubescent and sometimes are

deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

Distribution

''Quercus opaca'' is found in the states of Hidalgo,

Nuevo Leon Nuevo is the Spanish word for "new". It may refer to: * Nuevology, California, a town in California, United States * Nuevo (band), featuring singer and musician Peter Godwin * Nuevo (Bayamón), a settlement in Puerto Rico * "Nuevo", Spanish-langu ...

, San Luis Potosi, and

Tamaulipas Tamaulipas, officially the Free and Sovereign State of Tamaulipas, is a state in Mexico; one of the 31 states which, along with Mexico City, comprise the 32 federal entities of Mexico. It is divided into 43 municipalities. It is located in nor ...

in Mexico. According to

Plants of the World Online Plants of the World Online (POWO) is an online taxonomic database published by the Royal Botanic Gardens, Kew. History Following the Convention on Biological Diversity, the Royal Botanic Gardens in Kew launched Plants of the World Online i ...

it ranges from Tamaulipas south to

Oaxaca Oaxaca, officially the Free and Sovereign State of Oaxaca, is one of the 32 states that compose the political divisions of Mexico, Federative Entities of the Mexico, United Mexican States. It is divided into municipalities of Oaxaca, 570 munici ...

. This species is native to the

Mexican Plateau The Central Mexican Plateau, also known as the Mexican Altiplano (), is a large arid-to-semiarid plateau that occupies much of northern and central Mexico. Averaging above sea level, it extends from the United States border in the north to the T ...

region. ''Quercus opaca'' lives in arid tropical scrub habitats, usually 1200-2000 meters above sea level.

Conservation

Currently, there is a lack of data regarding the population size, population trends, and potential threats to the species. The absence of population data and threat assessments, along with under sampling, hinders researchers' ability to determine whether the species is at risk or not. Due to this, the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

classifies ''Quercus opaca'' as

Data Deficient A data deficient (DD) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as offering insufficient information for a proper assessment of conservation status to be made. This does not necessaril ...

References

{{Taxonbar, from=Q15339217 opaca Endemic oaks of Mexico Flora of Central Mexico Flora of Northeastern Mexico Flora of Southwestern Mexico Flora of the Sierra Madre Oriental Flora of the Mexican Plateau Plants described in 1924 Taxa named by William Trelease