The weeds described on this website are some of the worst invaders occurring in San Luis Obispo County, but are by no means an exhaustive list of our troublesome plants. For more information on the following weeds contact the San Luis Obispo County Agriculture Department, San Luis Obispo County Farm Bureau, the Farm Advisor's office (U.C. Cooperative Extension), or other local groups concerned about invasive plants.
 
• Artichoke Thistle – Cynara cardunculus  

• Arundo or Giant Reed – Arundo donax

• Barb Goatgrass – Aegilops triuncial 

• Cape Ivy – Delairea odorata

• French Broom – Genista monspessulana

• Hoary Cress – Cardaria spp.

• Jubatagrass – Cortaderia jubata

• Medusahead – Taeniatherum caput-medusae

• Oblong Spurge – Euphorbia oblongata

• Pampasgrass – Cortaderia selloana

• Perennial Pepperweed – Lepidium latifolium

• Purple Starthistle – Centaurea calcitrapa

• Spanish Broom – Spartium junceum

• Tree of Heaven – Ailanthus altissima

• Veldt Grass – Ehrharta calycina

• Wooly Distaff Thistle – Carthamus lanatus

• Yellow Starthistle – Centaurea solstitialis

Other Invasive Plants in San Luis Obispo County: 

• Bull Thistle - Cirsium vulgare

• Castor Bean - Ricinis communis

• European Beachgrass - Ammophila arenaria

• Ice Plant - Carpobrotus edulis

• Italian Thistle - Carduus pycnocephalus

• Periwinkle - Vinca major

• Poison Hemlock - Conium maculatum

• Puncture Vine - Tribulus terrestris

• Russian Knapweed - Acroptilon repens

• Russian Thistle - Salsola tragus

• Saltcedar/Tamarisk - Tamarix species

• Skeleton Weed - Chondrilla juncea

• Tocalote - Centaurea melitensis

• Wild Fennel - Foeniculum vulgare

• White Horsenettle/Silverleaf Nightshade - Solanum elaeagnifolium