''Pinus culminicola'', commonly known as Potosí pinyon or Potosí Piñón, is a

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as cu ...

in the pinyon pine group, native and

endemic Endemism is the state of a species being found only 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 foun ...

to northeast

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 ...

. The range is highly localised, confined to a small area of high summits in the northern Sierra Madre Oriental in Coahuila and Nuevo León, and only abundant on the highest peak, Cerro Potosí (3713 m). It occurs at very high altitudes, from 3000–3700 m, in cool, moist subalpine climate conditions.

Description

It is a medium-size

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

, reaching 1.5–5 m tall and with a trunk diameter of up to 25 cm. The bark is grey-brown, thin and scaly at the base of the trunk. 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, ...

('needles') are in fascicles of five, slender, 3–5.5 cm long, and deep green to blue-green, with

stomata In botany, a stoma (: stomata, from Greek ''στόμα'', "mouth"), also called a stomate (: stomates), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange between the internal air spa ...

confined to a bright white band on the inner surfaces. The cones are globose, 3–4 cm long and broad when closed, green at first, ripening yellow-brown when 16–18 months old, with only a small number of thin, fragile scales, typically 6–14 fertile scales. The cones open to 4–6 cm broad when mature, holding the

seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...

s on the scales after opening. The seeds are 9–12 mm long, with a thick shell, a white

endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the Embryo#Pla ...

, and a vestigial 1–2 mm wing; they are dispersed by the Clark's nutcracker and Mexican jay, which pluck the seeds out of the open cones. The jays, which uses the seeds as a major food resource, store many of the seeds for later use, and some of these stored seeds are not used and are able to grow into new plants.

History

Because of its isolation on a handful of remote mountain summits, Potosí pinyon escaped discovery until 1959. It differs from most other pinyon species in needle number, with 5 per fascicle, rather than 1–4, and in its consistently shrubby stature. It is most closely related to Johann's pinyon and Orizaba pinyon, like them having the leaf stomata confined to the inner faces; it also differs from the latter in its smaller cones and seeds. Like these two, the white-glaucous inner surfaces of the needles make it a very attractive slow-growing shrub, suitable for small

garden A garden is a planned space, usually outdoors, set aside for the cultivation, display, and enjoyment of plants and other forms of nature. The single feature identifying even the wildest wild garden is ''control''. The garden can incorporate bot ...

s. Like other pinyons, the pine nut seeds are edible, but the inaccessibility of the plants prevents significant collection for food.

References

External links

Photos of shrubs and foliage (scroll half-way down)
{{Taxonbar, from=Q3506484 culminicola Endemic flora of Mexico Flora of Coahuila Flora of Nuevo León Trees of Northern America Flora of the Sierra Madre Oriental Endangered biota of Mexico Endangered flora of North America