What is the plant the Greeks called silphion?

[downwardsfromzero]

Has anyone here heard of silphion?

In search of Silphion (opens pdf in browser)

A botanical-horticultural riddle: what is the plant the Romans called laser, laserpitium, or silphium, the English laserwort or magydare, the Arabs asa (hence asafoetida), and the Indians hing? Answer: a plant that might be lost forever and the Greeks called it silphion.

This is nothing to do with the tonic drink of the same name which is sold in Germany (although it is nonetheless rather good, if a little pricey) but this product did lead me to asking the question once I stumbled across the name Silphion in connection with asafoetida in a (German) book about psychoactive plants:

Nach Auffassung einiger Autoren handelt es sich bei dem antiken Silphion, eine antike Heilpflanze mit anscheinend psychoactiker Wirkung, um F. asa-foetida, vielleicht auch um Ferula moschata (Reinisch) Jonzo-Polj..

Which roughly translates as "In the opinion of some writers Silphion, an ancient medicinal plant with apparent psychoactive properties, was traded in antiquity and seems to be F. asa-foetida, perhaps also Ferula moschata."

But the Purdue essay seems to contradict this identification (and the German book isn't very well referenced). Any ideas?

(The prior occurrence of the word 'laser' is also mildly noteworthy.)