Bleak banyans are epiphytic plants with an appetite for positive energy. They are native to the rain forests of the kingdom of Enteria, which lies to the east of the Aureshan Empire, and they represent an ongoing challenge for the druids of that country because they spread rapidly with dangerous effects upon the ecosystems in which they grow.
Like their mundane cousins, bleak banyans are dependent upon a species of fig wasp for pollination. But as they grow, these magical trees feed upon the life force in their surroundings, both by absorbing the life-giving rays of the sun and by draining the vitality of the tropical arbors that serve as their hosts during the early stages of their development.
The banyans' life cycle begins when a ripened fig is consumed by a bird or other jungle creature. The ingested seeds of the plant are transported in these animals' guts until they are excreted elsewhere, splattering them against the bark of a suitable host. They germinate and take root, and a seedling grows, sending runners down the host's trunk and branches upwards to seek the sunlight. Within a season, the bleak banyan's roots penetrate the forest soil below, and it begins the process of strangling its host tree, penetrating its bark in order to leech away its essence.
By the end of its fifth year of growth, the bleak banyan achieves maturity (and usually the death of its host). As a mature plant, its boughs may span an area more than fifty feet in diameter. An area of positive energy deficiency takes shape in the shade of the adult tree, achieving an effect equivalent to a desecrate spell.
A mature bleak banyan puts forth a dense canopy, and this combines with its monopolization of life energy to make it nearly impossible for other plants to grow. In short order the forest understory around the tree is devoid of undergrowth, and after a year or two it effectively sterilizes the soil so that the forest has trouble closing the gaps caused by the death of a mature tree.
A single specimen of the bleak banyan species is seldom dangerous in its own right, except as a congregation point for roaming undead and the wasps that live in symbiosis with it. But as more specimens take root in the area, their influence overlaps with grim consequences for the surrounding ecology.
In a grove or thicket in which the canopies of at least seven mature bleak banyans overlap, the area of their desecrate effect leeches away all positive energy, granting it the minor negative-dominant trait (see page 149 of the Dungeon Master's Guide v. 3.5).
The heart of a dense forest of bleak banyans is even more perilous. Within a fringe of thickets with the minor negative-dominant trait lies a core, usually of older trees, where long-term shortages of positive energy allow the major negative-dominant treat to take hold of acres at a time. Left unchecked, a grove of bleak banyans grows like a cancer in an otherwise healthy forest, until no other plant life remains.
Druids in an area with a known population of bleak banyans exercise constant vigilance to prevent thickets from forming. Their efforts are hindered by the banyans' fruit, which is even more attractive to humanoids than it is to hungry jungle fauna.
Bleak banyans sequester a tiny portion of the positive energy leeched from their environment into their figs. In daylight, these fruit appear as unremarkable examples of their kind, not much different from their mundane cousins. But at night, the branches of a fruiting bleak banyan shimmer with hundreds or even thousands of tiny white stars.
The positive energy-infused figs can be dangerous to harvest because of the swarms of star wasps that live in symbiosis with the trees that bear them. These magical fig wasps' diet consists of bleak banyan pollen, nectar and fig juices, and they are highly protective of their trees. The harsh environment in which the thrive has bred into the species an innate tolerance for negative energy, and a swarm of angry star wasps can sting its victims to death in a matter of minutes.
The danger of harvesting the figs notwithstanding, there is a thriving market for them. Eaten raw within 24 hours of harvesting, they have the effect of a cure minor wounds spell and induce a mild euphoria which most creatures find pleasant.
Crushed and fermented into wine, the figs lose their healing potency and their euphoric properties intensify a hundredfold. Bleak banyan wine causes a potent, nearly sexual ecstasy in living creatures that imbibe it. The effect is highly pleasurable, making this substance both addictive and expensive. It is an important luxury good throughout Enteria despite its illegality, and it commands exorbitant prices on the black market.
The governments of every major state of Tolrea consider the wine contraband, and in many cases the mere possession of it is grounds for execution. This serves to curtail trade in the product, but makes smuggling incredibly lucrative for those willing to risk death for the sake of profit.
In Enteria, the harvest and processing of bleak banyan figs into wine is the province of ruthless cabals of necromancers that raise zombies to carry out the perilous work. Immune to the virulent toxins in the star wasp's sting, humanoid undead toil ceaselessly to pick, sort and transport the glittering fruit from their masters' jungle plantations. Through a combination of fermentation, necromantic processing and alchemical treatments the necromancers concentrate the figs' juices into wine.
The concentrated positive energy in the raw figs occasionally leads to mishaps that "kill" the servitor zombies employed in the production of bleak banyan wine. These incidents are common enough that there is a constant demand for fresh bodies to work the plantations, exacting a hideous price for the guilty pleasure of Enteria's decadent elite.