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 parks and large gardens. References External links Pinetum.org – Photos of Pinus johannis tree and foliage (scroll half-way down) Pinetum.org – Photo of cones (scroll half-way down) 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