List of biofuels (n = 40) and introduced species (n = 40) in the Hawaiian Islands (HI) analyzed in this study, with associated Weed Risk Assessment (WRA) scores, naturalization (Nat) or invasive (Inv) status, biofuel use and risk category (H = High, L = Low, E = Evaluate^*, NA = Not Assessable).

*<p>Risk designation for WRA scores of 1–6 follows use of a secondary screening developed by Daehler et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0005261#pone.0005261-Daehler1" target="_blank">[14]</a>.</p

Numbers (percentages) of species falling into the WRA risk categories within a group of species proposed as biofuels and a random selection of introduced species in Hawaii.

<p>Numbers (percentages) of species falling into the WRA risk categories within a group of species proposed as biofuels and a random selection of introduced species in Hawaii.</p

The number (percentages) of biofuel crops (n = 40) and a random selection of introduced (n = 40) species with their invasiveness status in this study; to calculate percentages for biofuels naturalized and invasive in Hawaii we use biofuel species present in Hawaii for the denominator (i.e., 38).

**<p>Binomial proportion tests significant at the 0.001 level.</p

Density distributions of WRA scores of biofuels compared to a random selection of other introduced species; scores were significantly different (Wilcoxon exact test W = 1135.5 p<0.001).

<p>Density distributions of WRA scores of biofuels compared to a random selection of other introduced species; scores were significantly different (Wilcoxon exact test W = 1135.5 p<0.001).</p