Link to photo in the Michael P. Frankis cone collection.

Range of Pinus nelsonii (Farjon and Styles 1997). Basemap from Expedia Maps.

Common Names

Nelson piñon (Lanner 1981).

Taxonomic notes

A highly distinct endemic with several unique features and no close relatives, it is only distantly related to the pinyons with which it has usually been classified in the past. The comment in its first description, "[a] very curious species" (Shaw 1904) holds ever more true each time it is studied. It is more aberrant than any other species in the genus and is probably of ancient origin.

Description

A small tree reported to 10 m (Shaw 1909, Perry 1991, Farjon and Styles 1997), though rarely more than 6-7 m tall or 20 cm dbh (M.P. Frankis, field notes, NE Mex., Nov-1991). Bark smooth, dull grey, cracking at base on older trees. Crown similar to the unrelated Mediterranean Pinus pinea: rounded, dense, with upcurved branches erect for their top 2-3 m. Leaves bright green, in fascicles of 3(-4), but the individual leaves remaining tightly 'zipped' (Bailey & Hawksworth 1988) together by their serrulate margins and so appearing single; they can be separated by rubbing the fascicle in the hand. Fascicles 4-7.5 cm long, about 1 mm thick; sheath fully persistent (unlike all other pines in subgenus Strobus). Seedlings have only juvenile foliage for several years; unlike other pinyons, foliage is green, not a glaucous blue. Cones cylindric, 6-12 cm long, 4-5 cm broad, green ripening to a rich bright red-brown, carried reflexed down the stem on stout downcurved peduncles 3-7 cm long and 7-10 mm thick. Scales finely wrinkled, short, stout, 20-25 mm broad, with a transverse ridge and a large but ill-defined 10-15 mm umbo. Seeds large, 10-12 mm, blackish with a red spot near apex, wing 1-2 mm, vestigial, usually remaining attached to the scale when seed removed. Seeds do not fall naturally from cone, but are dispersed by birds, mainly gray-breasted jay Aphelocoma ultramarina (Lanner 1981; M.P. Frankis, field notes, NE Mex., Nov-1991); after seed dispersal the cones fall leaving the peduncle on the branch. Cones mature in November about 18-19 months after pollination. The species is unique in Pinus in not showing a resting stage at 6-12 months (hence the ill-defined umbo); the six-month old conelets are already nearly half the mature size (Shaw 1909; M.P. Frankis, field notes, NE Mexico, Nov-1991). The cones are also unique in Pinus in sometimes having leaf fascicles on the peduncle; these fascicles are normal but fall before the cone is mature (M.P. Frankis, field notes, NE Mex., Nov-1991).

Range

NE Mexico, local (Lanner 1981) in Nuevo León, San Luis Potosí and Tamaulipas, at 1800-2500(-3200?) m elevation (Perry 1991). It usually grows mixed with P. cembroides and mixed xerophytic shrub vegetation including cacti and agaves in fairly flat, very dry areas (M.P. Frankis, field notes, NE Mexico, Nov-1991). See also Thompson et al. (1999). USDA hardiness zone 9.

Big Tree

Oldest

Dendrochronology

Ethnobotany

The local indians prefer its flavor to that of P. cembroides, with which it occurs (Lanner 1981).

Observations

Stands occur near poor quality roads near Doctor Arroyo and Miquihuana; four-wheel drive vehicles or horseback essential. See Perry (1991) for details.

Remarks

This species is listed as vulnerable by the World Conservation Monitoring Centre - Trees database. Although still locally abundant in its natural habitat, its range is restricted and it is vulnerable to fire damage in closed-canopy stands. Very few specimens are currently known in cultivation.

Citations

Shaw, G.R. 1904. Gard. Chron. ser.3, 36: 122, f.49.

This page edited by M.P. Frankis, Jan-1999.

This page is from the Gymnosperm Database
URL: http://www.conifers.org/pi/pin/ne.htm
Edited by Christopher J. Earle
Last modified on 9-Sep-2002