You've got your terms mixed up. No, most houseplants are not poisonous. Most houseplants are toxic if ingested but not poisonous. And especially not lifethreatening. Not to mention listed under the top 100 most toxic plants in the world. For something to be poisonous it must secrete poison and this plant does. 1 scrape and your dead in about 45 minutes. Extremely dangerous. If you have a cat and it so much as rubs up against the plant and then proceeds to clean itself even days later the cat is a goner. If this happens immediately pickup the cat and lock it in the shower or soak the fur in cold water and cleanse thouroughly for 45 minutes. Discard the plant. Their IS an anti-venom. Though hospitals don't generally carry it and most die before they can get to it. Your best bet is to cut off blood circulation to the entire infected limb. This should give you at least 3-4 hours to get to a hospital depending on the entry point and the time passed before cutting off circulation.
Where do you come up with this stuff? You really shouldn't make such ridiculous statements.
Here are some actual facts, rather than fantasy:
Family
Cycadaceae
Plant Description
Evergreen, palm-like; leaves 1-pinnately divided, glossy green, the leaflets narrow, with a sunken midrib and the margins rolled downward; pollen cone large and erect; the seeds on loosely arranged leaves around the stem, each seed large, plum-like, pale yellow-tan.
Origin
Japan.
Where Found
Houseplant or interiorscape; landscape as cultivated perennial in warm, coastal areas, as container plant in cool areas.
Mode
Ingestion.
Poisonous Part
Fleshy seeds, leaves, unprocessed flour from stem pith.
Symptoms
Vomiting, diarrhea, headache, dizziness, seizures.
Edibility
EDIBLE PARTS: Processed flour.
Toxic Principle
Glycosides and an amino acid BMAA.
Severity
TOXIC ONLY IF LARGE QUANTITIES EATEN.
Source:
http://www.ces.ncsu.edu/depts/hort/consumer/poison/Cycasre.htm
This isn't to say that Cycads aren't dangerous to animals, but it's main danger lies in it's palatability. Most poisonous (or toxic, the distinction you made is totally incorrect) plants are very bitter or unpleasantly aromatic, but apparently the Cycad tastes good.