Plant Species of the Bright Angel Trail: Two-Needle Pinyon Pine, Pinus edulis
See Plant Guide to Bright Angel Trail for an introduction to this page.
Identification status: high confidence. This is very easy to identify since it is the only pine at the Grand Canyon that has needles mostly in clusters of two (McDougall 1964 key on p. 29); see picture below.
There are two other pine species at the Grand Canyon: Pinus monophylla, with mostly single needles, and P. ponderosa, with needles in clusters of three. Pines have needles with sheaths at the base (see picture below); other trees in the Pine Family have leaves without a sheath at the base.
Pinus edulis and P. monophylla are extremely similar species, differing almost entirely in the number of needles per cluster. Since each species has some variability in the number of needles per cluster, often on the same tree, the determination of some specimens is difficult, and some botanists question whether these species are actually distinct and have proposed making one species a variety of the other.
According to the Flora of North America distributions, all specimens in nearly all of the Grand Canyon are P. edulis, with P. monophylla appearing possibly only at the extreme western end of the Grand Canyon (see distribution for P. edulis and P. monophylla).
It is amusing to note that in the central and eastern Grand Canyon, there are occasional vouchers of P. monophylla amidst the sea of P. edulis, and in the San Jacinto Mountains in southern California, there are occasional vouchers of P. edulis amidst the sea of P. monophylla. It is quite possible that these "out of place" vouchers are misdetermined specimens of the dominant species that are variants in the number of leaves per cluster.
From a SEINet search, there are 26 vouchers of this species from the Coconino County portion of the Grand Canyon. The nearest are at: Near Yaki Point; Yavapai Point; Nature Trail, South Rim; and Hermit Trail. Note that there may be additional vouchers at other herbaria not available through SEINet.
First occurrence on Bright Angel Trail: mile 0.00, elevation 6845 feet (2086 m).
Number of plants along Trail: At least 50 plants were found in at least 9 different locations in September 2007.
From 5 September 2007, mile 0.00:
Note that it is sometimes hard to see at a glance how many needles are in a cluster, since the needles are usually close together. I've splayed the needles apart between my thumb and index finger in the following picture:
The following picture shows the leaf sheaths, which are just papery bracts that surround the base of the needles. The leaf sheaths remain attached to the stem after the needles drop.
The above picture is a blow-up of a portion of the second picture above it.
See Resources for Grand Canyon Flora for further information on most of these references. Entries in the second column are either the name used in that source or a page reference. The name is linked to online pages when available. If a given reference does not contain this taxon, the entry is either left blank or contains a hyphen.
Family Pinaceae Scientific Name Pinus edulis 1987 Grand Canyon Flora Name Pinus edulis 1987 Grand Canyon Flora page 12 SEINet Image Page Pinus edulis USDA Plants Pinus edulis Flora of North America Pinus edulis Jepson Manual for California treatment Pinus edulis Jepson Manual illustration page 123 Kearney and Peebles Name Pinus edulis Kearney and Peebles Page # 52 Vascular Plants of AZ name Vascular Plants of AZ volume: page Huisinga et al 2006 name - Huisinga et al 2006 page numbers - Epple Name Pinus edulis Epple description page # 13 Epple pix # 23 McDougall 1964 name Pinus edulis McDougall 1964 page # 30 Brian 2000 Name Phillips 1979 name - Phillips 1979 page # - Stockert 1967 name - Stockert 1967 page # -
Copyright © 2007 by Tom Chester.
Permission is freely granted to reproduce any or all of this page as long as credit is given to me at this source:
Comments and feedback: Tom Chester
Last Update: 24 September 2007