 Bull thistle ( Cirsium vulgare ) , common mullein ( Verbascum thapsus ) , and Klamath weed ( Hypericum <unk> ) have been identified as noxious pests in Yosemite since the 1940s . Additional species that have been recognized more recently as aggressive and requiring control are yellow star thistle ( Centaurea solstitialis ) , sweet clover ( <unk> spp . ) , Himalayan blackberry ( Rubus armeniacus ) , cut @-@ leaved blackberry ( Rubus <unk> ) and large periwinkle ( <unk> major ) . 
