Yes, Nicotiana is toxic to dogs!
Dogs accidentally consuming the Nicotiana plants can show the following clinical symptoms: Vomiting, Prolonged Depression, Incoordination, Hypersalivaton, Sleepiness Or Excitation, Dilated Pupils, Low Body Temperature, Low Blood Pressure, Coma, Seizure And Death (In Rare Cases).
Nicotiana consumption is also toxic to Cats and Horses.
Toxic Principles Of Nicotiana: Nicotine.
More Info About The Nicotiana Plant
Scientific Name: Nicotiana glauca
Family: Solanaceae.
Also known as: Tree Tobacco, Tobacco, Mustard Tree.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.