Pine  (Pinus rzedowskii)

This rare Mexican pine tree was only discovered in 1969 and represents something of a taxonomic enigma, appearing to be a mid-point between the subgenus Strobus ('Haploxylon') and Pinus ('Diploxylon') (3)(5). These pines reach up to 30 metres in height (2), and mature trees have an irregular crown of branches (3). The dark brown bark is thick and deeply fissured, breaking easily into large plates (2); in younger trees the bark is smooth and greyish-green in colour (3). The slender green needles are 6 - 10 cm long and grouped in tufts of 4 - 5 (5). Oblong cones are borne at the ends of the branches, hanging down either singly or in pairs; they mature to a rich yellowish-brown or ochre colour before falling to the ground (3).

This extremely rare pine tree is restricted to three distinct populations in the Sierra Madre del Sur in the state of Michoacán, western Mexico (3)(5).

Inhabits limestone outcrops at elevations of 2,040 - 2,300 metres above sea level (3)(5).

The cones ripen in the autumn and then fall to the ground, thus dispersing their seeds (3).

Fire is a major risk to the survival of these rare trees. Many of the trees have fire scars and there appear to be very few young trees currently at the known sites (3), (5). The total area covered by these trees is not more than 30 hectares and an intense wildfire has the potential to wipe out the entire species (3).

The three remnant populations of this species need urgent protection and vigilance against forest fires (4). Additional security for the future of this species could be achieved by setting up small forestry plantations using seeds from the different populations and by introducing this tree to botanic garden collections (4). Such a rare and unique species makes a good candidate for protection measures (4).

Authenticated (20/3/03) by Dr Aljos Farjon, Royal Botanic Gardens, Kew.
http://www.rbgkew.org.uk