Opinion was at first divided as to the butchertrees' botanical or animal lineage. Their treelike appearance is belied by their behavior. It is a predatory organism very different from any tree ever seen. On several occasions these "trees" fold and open their long, sharp, twitching limbs in a grotesque slow-motion pantomime of a kill. Often, too, there are dried carcasses stuck on their spear-point branches.
Series of scans determine that they are animals. Some large butchertrees are surrounded by a few (usually four) smaller ones. Surrounding their wide trunk-bases are a number of yellow lanceolate growths, seemingly rooted beneath the rocky soil. Ever hour or so these growths start to move, swaying on some imaginary zephyr (for there might be no wind). Sometimes, an unnamed flyer insinuates itself amidst these dancing growths. The flyer blends in remarkably well, its color, shape, and movements causing it to disappear in the surrounding yellow fronds.
The cause for this mimicry the flyer possesses becomes immediately obvious when a pursuing predator, such as a prismalope, is after it. A few of these unnamed flyers will hide themselves among the waving fronds around the same butchertree. The little flyer's pursuer will pace around the base of the butchertree's trunk, searching for the unnamed flyer. The rapid pacing spirals into tighter circles until the pursuer is quite close to the butchertree.
So absorbed will the pursuer be in its small prey that it fails to notice the lightning descent of the spear-like arm of the butchertree. The limb pierces certain-sized victims with such force that a full meter is exposed on its other side, dripping with blood. The powerful arm lifts the kicking beast high into the air where, for the next three quarters of an hour, it dies, as its fluids are slowly drained.
The colors on the dying prey creature's body fade; its carcass shrivels perceptibly as pores in the impaling arm suck it dry. It becomes apparent that the treelike predator has finished when the remains are tossed down to land, in a cloud of dust, near the desiccated corpse of another victim (usually a Prismalope).Throughout the day, the butchertree catches a few victims, mostly prismalopes lured in by chasing the unnamed flyers.
The fronds have a barb near their bases. The fronds are attached to the trunk by a stretchy, underground tentacle. If a victim of an adult butchertree also gets caught on the fronds' barbs while still impaled and hefted into the air, this position apparently allows the fluids from the dying animal to flow more easily down its gullet.
At times three of the luckless prey are simultaneously held high in the air, in various stages of desiccation. The largest butchertree in a stand is connected to usually four smaller ones by thick, underground, tentacle-like umbilici. Since only the larger ones make kills, it is surmised that the others in the group are its offspring and that it is probably still sustaining them with nourishment until the day their own snapping limbs are powerful enough to kill prey. This takes about two years, depending upon the size and migratory patterns of the herds, since during periods of decreased prey, the butchertrees' metabolic level drops leaving only passive systems, such as the infrared receptor pits on the sides, active.It remains, to this day, uncertain as to how these odd, stationary creatures mate. The intimacy that the butchertree shares with the unnamed yellow flyer leads to speculation on a few possibilities. The flyer may be nothing more than an opportunistic symbiote gleaning morsels from the butchertree's kills. But somehow this is not convincing. One guess is that the flyer is, in some way, responsible for the continuance of the species. It acts as a lure for the butchertree; this is the most obvious contribution. It is also, however, an ideal candidate to carry sperm or eggs from one butchertree to the next. Or perhaps the flyer is itself the second sex, a sexual dimorphic extreme. Unfortunately the Expedition did not collect enough data to confirm any of these theories.