 Bull thistle ( Cirsium vulgare ) , common mullein ( Verbascum thapsus ) , and Klamath weed ( Hypericum perforatum ) 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 ( Melilot spp . ) , Himalayan blackberry ( Rubus armeniacus ) , cut @-@ leaved blackberry ( Rubus laciniatus ) and large periwinkle ( Vinca major ) . 
