Syn. Pinus cembroides subsp. orizabensis D.K. Bailey 1983; P. cembroides Gordon 1846, non Zucc. 1832.
Often treated (Perry 1991, Farjon and Styles 1997) as a subspecies of P. cembroides and allied to it in (sometimes) showing pink seed endosperm, but in other respects it is more closely related to P. johannis and P. discolor, sharing bark morphology, leaf number, stomatal distribution and resin composition closely with these (Bailey 1983, Bailey and Hawksworth 1990). The recently discovered occurrence of P. cembroides (sensu stricto) sympatric with it (Farjon and Styles 1997) also strongly suggests that this is specifically distinct from it (c.f. comments under P. johannis).
A small tree to 8-10(12) m tall, with an irregular rounded crown and shallow-fissured scaly blackish-grey bark, the fissures orange in colour, i.e., very similar to P. discolor (Bailey 1983). Leaves in fascicles of three and four mixed (about 80% in threes), mostly 4-6 cm long, stomata mostly confined to the inner faces, with very few on the outer face, thus leaves glossy dark green on the outer face and glaucous white on the inner faces, like P. johannis and P. discolor. Leaf sheath semi-persistent, the basal scales curling back into a rosette. The cones are larger than in any of these allied taxa, 4.5-7.5 x 5-8 cm (open) and up to 25 fertile scales in fully developed specimens, versus 3-4.5 x 4-5.5 cm with not over 15-18 fertile scales in P. cembroides, P. johannis and P. discolor, with larger but thinner scales, typically 30-35 x 16-20 x 2-3 mm (length x width x thickness), versus 20-25 x 15-18 x 3-4 mm in P. cembroides, and smooth, not wrinkled. It shares with P. remota the unusual feature noted by Bailey & Hawksworth (1988) in which the thin scales curl in at the edges on drying to give pointed scale corners. The golden-brown seeds also average larger, 14-17 mm, versus 12-15 mm in P. cembroides, the endosperm is white in fresh seeds but turns pink on drying (P. cembroides endosperm is always pink; that of P. johannis is always white). The 1 mm rudimentary seedwing usually remains in the cone after seed dispersal. (description compiled from Gordon 1846, Bailey 1983, Bailey and Hawksworth 1988, Bailey and Hawksworth 1990, Perry 1991, Farjon and Styles 1997, and M.P. Frankis' 1998 observations of the cultivated tree at Kew).
Mexico, SE of the capital: Puebla and Tlaxcala, in the area around Pico de Orizaba, at 2100-2800 m altitude, in a cooler, moister climate than other allied pinyons (Perry 1991, Farjon and Styles 1997). USDA hardiness zone 8.
A cultivated tree at Kew Gardens, UK, was 12 m tall and 32 cm dbh in 1984 (A.F. Mitchell); it is thought to be about 50-60 years old. No data available for wild trees.
It is, like P. discolor (but unlike P. cembroides), a principal host for the mistletoe Arceuthobium pendens (Bailey 1983, Hawksworth and Wiens 1996).
The resin composition is very close to P. johannis (Zavarin and Snajberk 1985, 1986).
Bailey and Hawksworth (1990) first described this taxon after observing the cultivated tree at Kew, then mis-labelled P. nelsonii (!), and carrying out detective work to locate matching wild-origin herbarium material, followed by a visit to the Orizaba region which proved to be its homeland.
The tree at Kew is a very attractive specimen, and the species well deserves further planting as an ornamental.
Bailey, D. K. 1983. A new allopatric segregate from central Mexico and a new combination in Pinus cembroides at its southern limits. Phytologia 54: 89-99.
Bailey, D. K. and F. G. Hawksworth. 1990. Change in status of Pinus cembroides subsp. orizabensis (Pinaceae) from central Mexico. Novon 2: 306-307.
Gordon, G. 1846. New plants from the Society's garden. J. Hort. Soc. London 1: 234-239.
Zavarin, E. and K. Snajberk. 1985. Monoterpenoid and morphological differentiation within Pinus cembroides. Biochem. Syst. Ecol. 13: 89-104.
Zavarin, E. and K. Snajberk. 1986. Monoterpenoid differentiation in relation to the morphology of Pinus discolor and Pinus johannis. Biochem. Syst. Ecol. 14: 1-11.
This page prepared 1999.02 by M.P. Frankis.
Last Modified 2012-11-23