Heating values of plants are very important parameters for characterization material cycle and energy conversion in forest ecosystems. Heating systems can use plants or other organic material. Local biomass resources for heating purposes are suitable and indicated in order to reduce the pollution of atmosphere caused by greenhouse gas emissions. In the present research four biomass species collected from various rural districts near Bucharest, Romania were used: Thorn (Xanthium spinosum), Arctium lappa (Greater burdock), Milk thistle (Silybum marianum) and Eryngo (Eryngium planum).The calculated parameters were: higher heating value, ash, moisture, nitrogen contents and bulk densities. The investigated species revealed positive characteristics which make them attractive raw materials for production of solid biofuels in the form of pellets. The obtained results are in a good agreement with literature statements and were calculated according to specific standard methods. From among the investigated species, Milk thistle (Silybum marianum) is the most perspective energy crop, having the highest heating value, lowest ash content and lowest moisture content. The determined parameters indicates Milk thistle to be a good material for domestic pellets production and other energy usages.