Quite likely the largest of the annual Rainbow Plant species, and also luckily one of the easier species to grow, though it's certainly presented me with its fair share of challenges.
B. guehoi is, like most of the annual species, an endemic to the northern reaches of Australia, and more specifically is only found within the Kimberley region, a hot, summer-dry tropical space stretching along the coast and a few (dozen) miles inland from about Broome to Kununurra and famed for its lack of habitation, rugged terrain, and fierce animal species (some of the most brazen saltwater crocodiles live along its coast). One often sees seeds of this species proffered with the locality "Kimberley," but this is somewhat redundant as it is found nowhere else. Personal experience has seen this species capable of developing into an oddly vining structure that might be more than 5 feet in length, and once it starts branching may have well over a dozen feet of stem on one plant. When grown in a properly large pot though, fed well, and under as strong a light as is possible (ie. full sun), they tend to be a little more compact, but still far more lengthy than most other species and of course with a greater tendency to develop lateral branches even before they begin flowering.
Also like most of the others in this genus B. guehoi requires special treatment of the seeds in order to germinate; while I have in the past found a 10% bleach solution soak for a few minutes to be moderately effective, treating with a 500-1000 ppm GA3 solution for 24 hours or so is more reliable and also safer for the user. Seeds should then be sown on the soil surface in the pot that they either will grow in for the rest of their lives, or smaller peat pots that can later be transferred into larger containers; this is a species that likes its space, and the best results will be found with single plants or very small groups in pots at least 6-8 inches deep and perhaps similarly as wide, if not more. A few different soil recipes are recommended, and may depend on what works in your location. I've personally had luck with an approximately 1:1:1 mix of peat, perlite, and long-fiber sphagnum as well as a more straight up 2:1 peat/sand or perlite mix, with a very shallow layer of milled sphagnum on the surface to help prevent damping off. Others have even found luck in pure sphagnum or sphag/perlite mixes.
In general, Byblis seem to benefit greatly from heavy feeding, as many annual carnivorous plant species do. Success can be found with regular misting of dilute fertilizers, sprinkling of small insects, bits of dried bloodworm, or similar components on the leaves, or even placing osmocote pellets in the soil (up to one per plant if planted in a group in a smaller pot, or perhaps 2-3 pellets in a large pot with one plant). The heavier the feeding, the more heavily branched and prolific in bloom they tend to be, but also the more short-lived. Maintaining a moderate to high humidity with good airflow is also important, to avoid damping off or fungal growth on the apical points and old food bits. My conditions are admittedly not perfectly ideal (smaller pot sizes and very humid), but even then a well-fed plant still lasts on average at least 5-6 months, and one particular specimen stuck around for well over 2 years and developed into a branching behemoth that draped across 3 different shelves in the greenhouse.
Flowers are large, more than an inch across and can number in the dozens on a single fully grown plant. In order to gain seeds however, one does require two genetically unique individuals to cross, as they are not self-compatible. Gathering pollen to transfer is not difficult either; holding the flower still and using a toothpick to flick the anthers will release it onto whatever surface is underneath, from which it can be gathered and transferred to a stigma on a different plant. If you don't have two different clones though, don't despair: B. guehoi actually fairly readily propagates from stem cuttings. The resulting plants do tend to be a little lankier, but as this is a lanky species to start with overall, it's not a grand change and multiple plants can be produced this way. Seeds tend not to be hard to find though, and this species suffers somewhat less from inbreeding depression than do the other obligate outcrossers, so one good colony can be maintained for years.