Pinus ponderosa</i> subsp. <i>scopulorum description

Tree growing on sandstone, Zion National Park, Utah [C.J. Earle, 24-Sep-1996].

Pinus ponderosa subsp. scopulorum (Engelmann) E. Murray 1982

Common Names

Rocky Mountain yellow pine (2), Rocky Mountain ponderosa pine (1).

Taxonomic notes

Syn: P. scopulorum (Engelmann) Lemmon 1897; P. ponderosa var. scopulorum Engelmann 1880.

This subspecies was formerly combined with subsp. brachyptera as P. ponderosa var. scopulorum Engelmann. However, the two subspecies readily distinnguished by the smaller seeds, green cones, and frequently two leaved fascicles of subsp. scopulorum.

It intergrades with P. ponderosa subsp. ponderosa in Montana at about 112°W. longitude.

Description

Trees to 24 m tall and 150 cm dbh. Twigs mostly red-brown, rarely glaucous. Leaves 2-3 per fascicle, (7-)10-17 cm × (1.2-)1.4-2 mm. Pollen cones yellow. Seed cones mostly symmetric, 5-10 cm; green when immature, apophyses of fertile scales moderately raised; umbo low pyramidal, narrowing acuminately to a stout-based prickle or short sharp spur. Seed body 3-4 mm; wing to 15 mm (1, 3).

Range

USA: Montana (E from 112°W), North Dakota, South Dakota, Wyoming, Utah, E Nevada, Colorado, Nebraska, Oklahoma. Mostly at 1000-3000 m (1).

Big Tree

Diameter 143 cm, height 44 m, crown spread 16 m. Locality: near Pagosa Springs in San Juan National Forest, CO (4).

Oldest

A crossdated age of 843 years for specimen BRY4002, collected in central UT by Schulman in 1956 (5).

Dendrochronology

Ethnobotany

This is the most important timber pine of the Rocky Mountains (1).

Observations

Widely enountered throughout most of its range. In my experience, dense and continuous stands may be seen in the Black Hills of South Dakota, so named for the dense stands of ponderosa covering their slopes. Exceptionally old and picturesque trees may be found throughout the deserts of southeast Utah, particularly on the lower slopes of the Abajo and La Sal Mountains; and at Vedauwoo in southeast Wyoming.

Remarks

Citations

(1) Kral in Flora of North America online.
(2) Peattie 1950.
(3) Little 1980.
(4) American Forests 1996.
(5) Brown 1996.
(6) Farjon & Styles 1997.