Nevada’s climate varies from desert regions in the south to semi-arid regions in the north. As such only 1.3% of total acreage in the state is classified as croplands (National Agricultural Statistic Service, 2002 census of Agriculture) with the majority of the state being unsuitable for many mainstream crop species. However, even with its harsh environment, Nevada still supports the growth of over 28,000 different native plant species. Many of which are highly productive and able to tolerate temperature extremes, extended periods of drought, and saline soils.
A number of these plants have evolved to survive Nevada’s harsh environment by accumulating chemical compounds that play roles in allelopathy1, antiherbivory2, and plant pathogen protection3. Interestingly, many desert plant species accumulate significant amounts of mixtures of low molecular weight non‐polar compounds that can be either be used directly as a liquid fuels or “cracked” to form a hydrocarbon fuel similar in quality to gasoline4,5,6. This finding and the 1970’s oil crisis prompted a series of “phyto‐prospecting” expeditions in the 1980’s to identify arid land plant species that could be used as petroleum alternatives for liquid fuel production4,5,7.
For Nevada, a report by Lemaire (1981) surveyed a large number of desert plants for biofuels production, and found that a limited number of these plants, could produce appreciable amounts of “bio-crude”. The types of compounds found in these plants were different than the standard triglycerides used in most present biodiesel production, and would require organic extraction and derivatization to produce usable fuels. From these efforts a number of promising candidate plant species were identified including gumweed (Grindelia squarrosa), rubber rabbitbrush (Chrysothamnus nauseosus), and gopherweed (Euphorbia lathyris), which were reported to accumulate greater than 25% dry weight percent as organic extractable material7.
While gopherweed originated from the Mediterranean region, rabbitbrush and gumweed are native to the Nevada (Checklist of Vascular Plants in Nevada http://www.swsbm.com/homepage/Floras/NVchklst.pdf). This research will examine gumweed and gopherweed’s potential as cultivatable biofuel/biomass crops for Nevada.