English

Abstract

An uncommon variety of perennial mustard occurred in a topsoil stripping area at a southeast Montana coal mine. Spring Creek Coal Company is attempting to reestablish Physaria didymocarpa (Hook.) A. Gray var. lanata A. Nelson, woolly twinpod, in reclamation. This recognized variety is rated S1 in Montana (at risk, imperiled); the G5 (common, secure) global designation refers to generic Physaria didymocarpa (common twinpod), whereas T2 (less imperiled than S1, it occurs also in WY) refers to the trinomial (var. lanata). It is more of a stenotopic stress-tolerator than a competitor. In the wild, fruits aren't produced every year and empty capsules are common, hence the prospects for collecting seed appeared dim. Fifty mature plants were collected from the area permitted for mining and transplanted into five-gallon Smartpots™ with a mix of native scoria soil, manure-based compost, and commerical mycorrhizal inoculant. One year later, most were magnificent specimens bearing more and bigger fruits than seen in nature. Because seed production is naturally meager, cloning was implemented to propagate seedlings to become nursery-raised transplants. Tissue culture was easily started from seed provided by three of the original transplants. However, transplanting and acclimatizing them to commercial greenhouse conditions presented other problems. Seedling survival was just 15%. Seed collected from the initial transplants, prompted by their prodigious fruit production, yielded about 90% survival. From these two propagation methods, more than one thousand 115-ml (seven- cubic-inch) stubby cells were raised in 2008. An experimental population was planted in fall 2008 into suitable mine reclamation. Approximately 800 seedlings will be transplanted in spring 2009, this effort to be repeated in subsequent years. In addition to delicate clone roots/indurate agar, challenges include nursery rot due to the tendency to collect water at the rosette center, providing good root/soil contact when transplanting into appropriate coarse substrate, and possible herbivory. Flexibility and adaption are key elements of the revegetation program. Some lessons may guide others similarly engaged.