** Deadly Nightshade (死亡草) - Atropa belladonna**

Deadly Nightshade, also known as Belladonna or Deadly Nightshade, is a highly toxic plant that belongs to the Solanaceae family. It's native to Europe and parts of Asia but has been naturalized in many other regions due to its ability to thrive in disturbed areas and waste ground. The leaves, stems, seeds, and berries of this plant contain tropane alkaloids which are responsible for its toxicity.

Ingesting even small amounts of these toxins can lead to severe symptoms such as hallucinations, delirium, convulsions, coma and even death. Prolonged exposure can cause permanent damage to the brain and nervous system.

Oleander (鸢尾草) - Nerium oleander

Oleander is an ornamental flowering shrub native to Mediterranean region but widely cultivated in tropical climates around the world for its beautiful flowers. Its leaves are narrow elliptical with pointed tips while stems are woody or herbaceous.

While it may be aesthetically pleasing, oleander is highly toxic when ingested due to cardiac glycosides found within its leaves and flowers. Even minor contact with these parts can cause irritation on skin.

Castor Bean Plant (大麻籽) - Ricinus communis

Castor Bean Plant is an annual plant grown primarily for castor oil production from seeds' oil-rich embryo inside seed kernels.

All parts of this plant contain ricin – one of the most toxic substances known – making it extremely dangerous if ingested by humans or animals alike.

Yew (樫树科植物，尤指樫树和槲寄生) - Taxus spp., especially Taxus baccata

Yew plants belong mainly within genus Taxus where several species exist including English Yew (Taxus baccata), Japanese Yew (Taxus cuspidata), etc.

They're often used as ornamental plants because they have attractive foliage and red berries containing a deadly toxin called taxine which causes vomiting diarrhea nausea headache seizures coma liver failure kidney failure heart attack respiratory failure eventually leading death.

Lily-of-the-Valley (小白菊; Convallaria majalis) & Aconitum spp.(Aconite; Monkshood; Wolf's Bane)

Lily-of-the-Valley consists mostly of green glossy leaflets arranged on stem below white fragrant flower clusters shaped like a bell that blooms from late spring until early summer.

However all parts contain cardiac glycosides lycorine saponins atropine muscarine causing nausea vomiting abdominal pain diarrhea headache confusion dizziness irregular heartbeat low blood pressure eventual coma death if ingested by humans or pets accidentally ingest any part without proper handling precautions under professional guidance might result in serious harm too.

6th option: Daffodil

Daffodils have trumpet-shaped flowers usually yellow color commonly found throughout gardens across temperate regions worldwide.

Their bulbs hold toxic compounds called lycorine along with some other chemicals that produce nausea vomiting abdominal pain diarrhea headaches flushing cold sweats high fever rapid heartbeat sometimes paralysis eventual heart attack/heart rhythm disorders resulting in fatality upon ingestion.

Remember always handle any potentially harmful substance carefully!