Plants are known to have limited capacity to utilize organic phosphorus (P) forms despite their abundance in soil. Gulf and Marshall ryegrass (Lolium multiflorum), which accumulates P in their shoots, were grown aseptically in agar-nutrient medium enriched with different organic P  substrates (GMP, AMP, ATP and IHP) to study the pattern of growth, P accumulation and the activities of root phytase and phosphomonoesterase. Plants exhibited a differential pattern of growth in respect of the substrates, with minimum growth in the GMP- and maximum growth in the IHP- supplemented media. Both ryegrasses accumulated P up to 1% (shoot dry weight) depending on the type of organic P in the media. The pattern of phytase and phosphomonoesterase activities in these grasses was interesting. The enzyme activities of plants grown in IHP-enriched media were either equal to or higher than controls that were grown in the media devoid of any P source.