Cypirion cactus thistles
The Cypirion cactus was a plant with many long, sharp thistles.
In 2370, an intimate moment between Commander William T. Riker and Tactical Officer Rebecca Smith in the USS Enterprise-D arboretum was cut short when Riker rolled onto a Cyprion cactus. (TNG: "Genesis")
The Star Trek Encyclopedia, 4th ed., vol. 1, p. 173 referred to the plant as the "Cyprion cactus", and specified its spines to be 6 to 12 centimeter long.