Agronomy and Horticulture, Department of


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Published in American Journal of Botany, Vol. 12, No. 8 (Oct., 1925), pp. 502-509. Copyright 1925 Botanical Society of America. Used by permission.


Ten years ago, while studying the vegetation of semi-arid eastern Washington, interest in root studies was aroused because of the extensive root systems of the native species. Balsamorrhiza sagittata, the first plant excavated, is representative. The strong tap root reaches a depth of six feet, and very numerous branches run laterally to distances of about two feet. Further investigations in several other states showed that extensive root systems are the rule among grassland species. Andropogon haliji, with exceedingly well branched fibrous roots seven feet deep, is representative of many of the dominants. About ninety percent of the more important species are rooted well below the two-foot level, and not a few, such as Liatris punctata, extend to depths of fifteen to twenty-two feet.