Exotic Flora of the Multiverse: Watchweed & Sentry Wasps

Watchweed

Description:  Watchweed (sometimes also called rose grass) resembles agrostis stolonifera ("creeping bentgrass") with faint red highlights at the tips of its leaves.  It spreads by runners and grows rapidly in temperate or semi-tropical conditions, although it is somewhat vulnerable to drought.  The plant is mildly toxic to most animal life, and can be fatal to small mammals and insects that attempt to feed upon it. 

Creatures larger than a small rabbit intruding on a field of watchweed will encounter its most noteworthy feature.  The plants react to being disturbed by collectively producing a piercing sound akin to a police whistle by rasping together specialized structures in their leaves through vascular flexing.  The sound is quite loud even from a small patch the grass, and a large field can reach intolerable volumes if intruders persist.  Even large animals will generally withdraw in short order from fear or sheer annoyance, although intelligent creatures can soldier on without much difficulty by covering their ears.  Conversations during an large "watchweed alert" are nearly impossible, even when shouting.

Extremely strong winds can produce a "false alarm" in watchweed fields, although the sound is different enough that it can be differentiated from that made by animal movements with some experience. 

Uses:  Wild watchweed is fairly common in many areas.  It resists predation by herbivores quite well and even produces some of its own fertilizer in the form of small animal and insect carcasses who've been poisoned to death by attempted feeding.  Stumbling into a patch will trigger an alarm which may attract larger predators, who are accustomed to the sound signaling the presence of sizable prey.  The noise certainly drives off less aggressive animals, and many a hunt has been spoiled by watchweed and a careless hunter.    

Watchweed is commonly planted around sites as a security measure, albeit at some distance from the structures being protected to limit annoyance from false alarms.  It requires tending to keep it from spreading into unwanted locations and regular watering in arid regions, but must be left fairly long (at least 6" - it can reach almost 2') or volume will suffer.  There are no known ways to silence watchweed short of destroying it outright, so intruders must find a way to bypass it if trying to be stealthy.  Unless previously familiar with the plant differentiating it from normal ornamental grasses is a task for a trained botanist, although once it starts whistling the source of the noise is obvious.

It is possible to harvest watchweed.  The clippings can be refined to produce an emetic poison strong enough to sicken larger creatures for several days if ingested or injected.  A single dose for something the size of a human requires fresh cuttings from several thousand square feet of watchweed and it can only be harvested once a month in optimal growing conditions, so output is fairly low.  The emetic may have some utility as medicinal ingredient as well, but this requires further procedures and suitable training.

Complications:  Aside from the noise and irritation of the occasional "false alarm" caused by wind or animal intrusions, the main risk encountered from watchweed is the territorial insect known as the sentry wasp.  These creatures (which don't resemble wasps much at all beyond flying and injecting painful venom) have a semi-symbiotic relationship with the plants, building their subterranean nests beneath it and preying on the few other species of insects and small animals that can resist the plants' natural toxicity.  Sentry wasps have no venom glands of their own.  Instead they use an internal organ to transform chewed watchweed leaves and soil chemicals to produce a strong venom that they inject with a "sting" made of modified mouthparts.  Once their target succumbs they suck their internal fluids out with the "sting" working in reverse.

While an individual sentry wasp is merely a painful irritation to larger animals (including humans) a dozen or more of them can inject enough venom to trigger severe vomiting, shock, and even unconsciousness.  Fatalities are rare but not unknown.  Domesticated watchweed is generally free from sentry wasp infestations, but keeping them that way requires some vigilance and continued effort.  Wild watchweed fields of any size will almost certainly have at least one hive beneath them, although the insects are dormant during the colder seasons.

Design Commentary:  This one can certainly fit into a fantasy game easily enough, but I finally remembered that "system agnostic" should work for scifi games as well.  Watchweed and sentry wasps would be fine xenospecies, something to complicate adventures on newly discovered worlds or settled ones as well.  Watchweed in particular might fit well in an alien ecosystem where most of the motile life forms rely heavily of hearing and/or echolocation as their primary sense, and might just be one of many "noisy" types of plant life on a world.