Plant Species of the Bright Angel Trail:
Munz's bedstraw, Galium munzii ssp. ambivalens
Munz's bedstraw, Galium munzii ssp. ambivalens
See Plant Guide to Bright Angel Trail for an introduction to this page, especially the Introduction To These Species Pages.
Galium munzii ssp. ambivalens is endemic to Arizona, found in just Coconino and Mohave counties.
Characteristics
Identification status: No Galium determination can be considered secure without flowers and fruit. Unfortunately, I've hardly ever encountered specimens with flower and fruit in my April/May and August/September visits to the Grand Canyon.
Instead, I've tried to use the vegetative appearance of the plants, along with the species present in this part of the Grand Canyon, to try to determine them. This may or may not result in reliable determinations.
In the area of the Bright Angel and South Kaibab Trails, there are only four recorded Galium species. The following table gives some distinguishing characteristics of each one.
| Taxon | Elevation Range (feet) | Characteristics |
|---|---|---|
| G. aparine | 1200-8000 | Annual, leaves in whorls of 6-8 (fewer in lowermost whorls) |
| G. munzii | 5200-8200 | Perennial with woody base, leaves lanceolate or ovate, tapering to acute apex. |
| G. stellatum ssp. eremicum | 1200-5000 | Shrub, leaves lanceolate to needle-shaped, rigid, narrowed gradually to sharp apex |
| G. wrightii | 5500-7000 | Perennial with woody base, leaves linear, oblanceolate, rarely elliptic, narrowed gradually to broad insertions, narrowed abruptly to acute, often pungent, apices; corolla purplish, red, pink, or rarely yellow |
All taxa have leaves in whorls of 4 except for G. aparine, and all taxa have white, yellow, greenish, greenish-yellow or reddish corollas except for G. wrightii. All taxa have leaves roughly the same length, ~7-20 mm, except for G. aparine, which has leaves of 13-31 mm length.
The elevations are from the 1987 Grand Canyon Flora by Phillips et al; the characteristics are from the Galium treatment by Dempster in the 1995 Vascular Plants of Arizona and from McDougall 1964.
G. munzii has two subspecies, distinguished by their leaves and by geographic location in the Dempster treatment:
1 Leaves hispid, narrowly to broadly ovate, rarely lanceolate; nw Mohave Co. ... ssp. munzii
1' Leaves glabrous or nearly so, lanceolate to narrowly ovate; Coconino and Mohave cos. ... ssp. ambivalens
Although Dempster places only ssp. ambivalens in Coconino County, Phillips et al places ssp. munzii there, and online vouchers exist from there as well.
G. munzii ssp. ambivalens was called G. watsonii in Kearney and Peebles and in Phillips et al.
If the characteristics in the above table are correct, it should be easy to separate the species in vegetative form as follows:
1 Plant annual, leaves in whorls of 6-7 ...G. aparine
1' Plant perennial or shrub, leaves in whorls of 4 ... (2)2 Plant woody well above the base with many short, spreading branches; elevations below 5000 feet ... G. stellatum ssp. eremicum
2' Plant woody only near base, the branches longer and more upright; elevations above 5000 feet ... (3)3 Leaves lanceolate or ovate ... G. munzii
3' Leaves linear, oblanceolate, rarely elliptic ... G. wrightii
All of the plants found so far on the upper Bright Angel Trail are perennials with narrowly lanceolate to ovate glabrous leaves, which would make them Galium munzii ssp. ambivalens. However, there is such striking variation in the leaf shape, with the narrowly lanceolate plants having almost linear leaves, that I am not sure whether those plants are this determination. The plants with almost linear leaves also seem to have a leaf base that fits the description of the leaves of G. wrightii. See the pictures below, and let me know if you think these fit another taxon better.
See also Plant Species of the South Kaibab Trail: Wright's bedstraw, Galium wrightii; Plant Species of the Bright Angel Trail: common bedstraw, Galium aparine; and Galium stellatum ssp. eremicum from the Borrego Desert.
From a SEINet search on 2 September 2008, there are 14 vouchers of G. munzii from the Coconino County portion of the Grand Canyon. Five of those vouchers are determined as ssp. ambivalens; the rest are determined only to the species. Four additional vouchers are from the Little Colorado River; all are determined as ssp. munzii.
One voucher is from this trail, determined just to the species: Along Garden Creek. Note that there may be additional vouchers at other herbaria not available through SEINet.
First occurrence on Bright Angel Trail: mile 0.59, elevation 6477 feet (1974 m).
Number of plants along Trail: at least 40 plants were found in at least 9 different locations in May 2008.
Pictures
Plant 1, from 5 September 2007, mile 0.59:
Plant 2, from 5 September 2007, between mile 1.5 and 2.2. The plant is covered with red dust from the trail:
Plant 3, from 4 May 2008, past mile 3.0:
Plant 4, from the Dripping Springs Trail, 15 September 2006:
The following plants were found in other locations along the Bright Angel Trail, but mostly have longer, narrowly-lanceolate leaves, and I'm not sure they are the same taxon:
Plant 5, between mile 1.5 and 2.2, 4 May 2008:
Plant 6, between mile 1.5 and 2.2, 5 September 2007:
Plant 7, past mile 2.2, 4 May 2008:
References
Online pictures for Galium munzii are scarce. The only one I could find was at SEINet, which matches fairly well the first four plants shown on this page. (The Calphotos pictures of "G. munzii" by Brousseau are almost certainly misidentified if the location is correct, since G. munzii does not occur at Anza-Borrego Desert State Park. I've annotated it to remove the determination of G. munzii.)
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.