abundant angles appearances castor-beans castor-oil castor-oil-plant castor-seeds cluster clusters common cotyledons Euphorbiaceae fast-growing flower flowers foliage highly-toxic inflorescences invasive large large-leaves leaf leaves medicinal palm-of-Christ palma-Christi poison poisonous ricinus-communis seed-pods seedhead shrub shrubbery spiky-green-seed-capsule spiny surface surfaces textured textures toxic toxins vegetation wasteland-weed weed widespread agriculture alternative fuel biofuel castor ethanol farm field green greenery mamona oilseeds plant plantation