A security bush appears to be an innocent shrub, when in fact it is an active security device. This device was invented on the Arrank Habitat in Martian orbit in the Sol system just prior to the nanoswarm disaster. The design was shared with several early colony ships, and left the solar system before the nanodisaster.
Most Security Bushes are loaded with pneumatic powered darts, sometimes coated in a poisonous substance - either paralytic or lethal to the local general populace. When someone or something that isn't authorized attempts to enter the area the security bush is protecting, it fires a volley of darts at the intruder and triggers an alarm to warn other security systems. these devices make use of bioborg, provolve and cybernetic enhancement, and can be designed to look like most any type of shrub, small tree, or even a patch of grass.
While mostly supplanted by more robust systems, such as ubiquitous angelnets, Security Bushes were quite the high-tech option in the early interplanetary era, all the way up through the beginnings of the first federation. The concept of the ubiquitous angelnet has mostly supplanted the security bush in modern times.
At the height of their use, the most popular model was known as the Arrankalean Needler, and actually fired a wide range of projectiles, from hypersonic bullets to a sticky fluid that entangled the victim. The Arrankalean Needler was most famous for its rigorous sensors and unblemished service records. For the first two hundred years after its invention, no Arrankalean Needler was ever fooled into passing an unauthorized person into it's protected area. They were, however, not impossible to overpower.
Inspection of the plant has since determined that the Arrankalean Needler was sentient, but non-sophont, and having a narrow transapient spike (usually to S:1.2 or so) in abilities required to identify authorized beings.
If the Needler is left to grow in the wild, it can reproduce, and will program its offspring to follow the same orders it was given. There have been a few documented cases of security bushes taking over a large portion of the biosphere after being abandoned. Wild security bushes are sometimes a serious nuisance, carrying out programming laid down thousands of years ago.