Mojave National Preserve - Others

There are two unique plants found at Mojave National Preserve that do not fit neatly into any of the other categories; they are neither flowering plants nor conifers, neither mosses nor liverworts. They are cryptogams, that is, seedless plants, but they are not ferns. They are Mojave spike-moss, ( Selaginella leucobryoides ) and smooth scouring rush ( Equisetum laevigatum ). They belong to the plant divisions Lycopsida (Club mosses) and Spenopsida (Horsetails), respectively, two groups known from the Devonian period, between 345 and 395 million years ago. The club mosses and horsetails appear in the fossil record earlier than any other vascular plants groups except the ferns, which appeared around the same time as horsetails.

The division Lycopsida contains approximately 1,000 species in five genera. Like Mojave spike-moss, all living species are small with simple leaves. Lycopsids were not always so diminutive; fossil lycopsids from the Carboniferous period (between 340 and 280 million years ago) reached heights of over 100 feet. The remains of fossil lycopsids contributed to the formation of coal. Mojave spike-moss, an endemic to California, is uncommon throughout its range and is only found in San Bernardino and Inyo counties. It grows among rocks and crevices, generally limestone, and is found in shrubland and woodlands from 600 to 2300 meters elevation. Within the preserve it may be observed in the Providence Mountains.

All fifteen living members of the division Spenopsida, the horsetails, belong to one genus, Equisetum. Horsetails are rather strange looking plants, developing an above ground shoot from an underground stem, or rhizome, and having scale-like leaves. Horsetails often grow in sandy places and incorporate silica into their stems. The silica imparts an abrasive quality to the stems, which were at one time used for cleaning pots and pans. Many other larger species of horsetails, which grew up to 45 feet in height, were dominant species of the Carboniferous. Like lycopsids, the fossil remains of these giant horsetails contributed to the formation of coal. Smooth scouring rush may be found at moist areas below 3000 meters which are gravelly or sandy, such as Soda Springs.