Frequency distribution patterns were developed for distance to nearest neighbor of the same species for Larrea tridentate (Sesse & Moc. ex DC.) Cov., Ephedra nevadensis S. Wats., and Acamptopappus shockleyi A. Gray. The distances between shrubs had been determined previously in another study. About one-third or more of the nearest neighbor of its own kind was within less than one meter for each species, indicating that it was usually within the same shrub clump, which in turn is indicative of an aggregating effect. For L. tridentata and E. nevadensis much of this could be from the same original plant by crown diffusion (L. tridentata) or underground spreading (E. nevadensis). None of the three gave evidence of spacing at regular intervals when the nearest neighbor of a single individual within a shrub clump was outside that clump. Rather, they appeared to be randomly distributed under this condition, except possibly for A. shockleyi.
Wallace, A.; Romney, E. M.; and Kinnear, J. E.
"Frequency distribution of three perennial plant species to nearest neighbor of the same species in the northern Mohave Desert,"
Great Basin Naturalist Memoirs: Vol. 4
, Article 11.
Available at: http://scholarsarchive.byu.edu/gbnm/vol4/iss1/11