Plant Species of the Bright Angel Trail: Peppergrass, Lepidium sp.
See Plant Guide to Bright Angel Trail for an introduction to this page.
Characteristics
Identification status: only determined to genus with high confidence; species has not been determined.
It is usually a pain in the butt to determine the species of Lepidium, at least for southern California plants. One generally needs both flowers and fruits, which only appear together for a brief time during the year. Also, the differences between species, at least in the keys, are subtle in some cases, and the keys are somewhat ambiguous or even incorrect in places, especially with respect to the petal length relative to the sepals. Without a sample in hand, I'm reluctant to even try to determine the species.
Purely going on elevation, using the list of taxa known to occur near this area, there are three Lepidium species in the Grand Canyon flora found in this area: Lepidium lasiocarpum var. lasiocarpum, L. montanum, and L. perfoliatum.
These plants are clearly not Lepidium perfoliatum since the leaves do not surround the stem at their base.
L. montanum does not fit well, since according to McDougall its basal leaves are pinnately divided into linear lobes, and it has a fruit with a small notch. However, the basal leaves might be missing on the plant in my picture, so I can't rule this determination out absolutely.
L. lasiocarpum fits well for the leaves, having leaves linear to oblanceolate, toothed or lobed. It usually has at least some hairs on the fruit. Although no hairs are visible on the fruit in my pictures, it is hard to be sure there are in fact no hairs present without microscopic examination.
Hence it is possible that the likely determination here is Lepidium lasiocarpum var. lasiocarpum, but in order to be sure, I'd need to check the petals and the hairs on the stem in order to verify it with the McDougall key:
8c. Petals minute or lacking, never as long as the sepals. 10a. Stems branched from base, spreading, seldom erect, hairy with stiff, spreading hairs....Lepidium lasiocarpum
Of course, it is also possible this is one of the other Lepidium species found elsewhere at the Grand Canyon.
From a SEINet search, there is a voucher of L. densiflorum var. ramosum from the Bright Angel Trail at an elevation of 3800 feet, and many vouchers of L. montanum nearby, including Yaki Point and the Grandview Trail.
First occurrence on Bright Angel Trail: mile 0.00, elevation 6845 feet (2086 m).
Number of plants along Trail: Just five plants were found in a single location in September 2007. More plants would be expected in a wetter year.
Pictures
From 5 September 2007, mile 0.00:
References
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.
Since the determination is unknown, no references are given here.