''Pinus johannis'', the Johann's pine, is a pine in the pinyon pine group, native to

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. The range extends from southeast Arizona and southwest New Mexico, United States, south in Mexico along the Sierra Madre Occidental and the

Sierra Madre Oriental The Sierra Madre Oriental () is a mountain range in northeastern Mexico. The Sierra Madre Oriental is part of the American Cordillera, a chain of mountain ranges (cordillera) that consists of an almost continuous sequence of mountain ranges that f ...

to southern Zacatecas and

San Luis Potosí San Luis Potosí (), officially the Free and Sovereign State of San Luis Potosí ( es, Estado Libre y Soberano de San Luis Potosí), is one of the 32 states which compose the Federal Entities of Mexico. It is divided in 58 municipalities and i ...

. It occurs at moderate to high altitudes, from , in cool, dry climate conditions.

Description

''Pinus johannis'' is a small to medium-size tree, often just a

shrub A shrub (often also called a 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 ...

, reaching tall and with a trunk diameter of up to . The bark is grey-brown, thin and scaly at the base of the trunk. The

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

('needles') are in mixed fascicles of three and four, slender, long, and deep green to blue-green, with

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

confined to a bright white band on the inner surfaces. The cones are globose, 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 6-12 fertile scales. The cones open to broad when mature, holding the seeds on the scales after opening. The seeds are 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 and ...

, and a vestigial wing; they are dispersed by the Mexican jay, which plucks the seeds out of the open cones. The jay, which uses the seeds as a major food resource, stores many of the seeds for later use; some of these stored seeds are not used and are able to grow into new trees. ''Pinus johannis'' is nearly

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...

: nearly all individuals produce either male or female cones only, and trees do not appear to change their sex expression over time.

History

''Pinus johannis'' is a recently described pinyon pine, discovered by

Elbert L. Little Elbert Luther Little, Jr. (born October 15, 1907, in Fort Smith, Arkansas; died June 23, 2004) was an American botanist whose career spanned 70 years and largely concerned forest botany. Although he was born in Arkansas, and died in Oregon, he grew ...

in 1968 when comparing pinyons growing in Arizona with those of typical Mexican pinyon ('' Pinus cembroides'') in Mexico; he described it as a variety of Mexican pinyon, ''Pinus cembroides'' var. ''bicolor'', noting the very different stomatal placing on the leaves; it also differs in needle number, with 3–4 per fascicle, rather than 2–3; in the cones having thinner scales; and in having a denser, more rounded crown. Further research by the French botanist Marie-Françoise Robert-Passini, the American botanists Dana K. Bailey and Frank G. Hawksworth and others, has shown that it is better treated as a distinct species. Although often occurring together with Mexican pinyon, it is reproductively isolated from that by its pollination being a month to two months later in summer, rather than in spring, thereby preventing hybridisation. As Robert-Passini and Bailey & Hawksworth were working in different areas at about the same time, it was raised to species rank twice, first as ''Pinus johannis'' by Robert-Passini (naming it after her husband Jean) examining specimens in the Sierra Madre Oriental in Mexico, and then later as ''Pinus discolor'' by Bailey & Hawksworth examining specimens in the northern Sierra Madre Occidental in Arizona. There are slight differences between the plants in the two ranges; those in the eastern being more shrubby and with larger cones than those in the western range, and also differences in the resin composition; they are though generally very similar and recognition of both as separate species from each other does not appear warranted. Some botanists also still include ''P. johannis'' in Mexican pinyon as a variety or even not distinguished at all, accounting for reports of "Mexican pinyon" in Arizona and New Mexico. This is despite the two frequently occurring together at the same sites with no hybridisation. ''Pinus johannis'' is most closely allied to Orizaba pinyon ('' Pinus orizabensis'') and Potosi pinyon ('' Pinus culminicola''), with which it shares the leaf structure with the stomata confined to the inner faces; it differs from the former in the smaller cones and seeds, and from the latter in fewer needles per fascicle (3–4 vs 5).

Uses

The edible pine nut seeds are collected in Mexico to a small extent. The white-glaucous inner surfaces of the needles make it a very attractive small tree, suitable for

park A park is an area of natural, semi-natural or planted space set aside for human enjoyment and recreation or for the protection of wildlife or natural habitats. Urban parks are urban green space, green spaces set aside for recreation inside t ...

s and large gardens.

References

External links

Pinetum.org – Photos of ''Pinus johannis'' tree and foliage (scroll half-way down)

{{Taxonbar, from=Q3506525 johannis Trees of the Southwestern United States Trees of the South-Central United States Flora of the Southwestern United States Flora of Northwestern Mexico Flora of Northeastern Mexico Flora of Sonora Flora of Zacatecas Flora of San Luis Potosí Flora of Arizona Flora of New Mexico Flora of the Sierra Madre Occidental Flora of the Sierra Madre Oriental Edible nuts and seeds Garden plants of North America Drought-tolerant trees Dioecious plants Plants described in 1978 Flora without expected TNC conservation status