Bouffant Mycostrum
Silk mycostrum spread southward with its silk knightworm symbiotes, evolving into bouffant mycostrum as bouffant knightworms developed. They retained the same three forms as their ancestor, but they became dependent on their knightworms for survival, and they developed the ability to grow much greater complexes of connected nests.
Like their relatives, the bouffant mycostrum consists of many fibers of mycelium, capable of photosynthesis and of feeding by decomposing dead matter, which is their main source of nutrients. Their greatest bulk comes in their nest form, which cover the ground in a whorl of fibers, soft and thick. Though some strands may extend into the ground, the vast majority stays on the surface. Given their drier environment, they have become more adept at retaining water. Wet portions of the mycostrum become spongy, and the outer layers form a waxy cuticle. Nests provide shelter for their knightworm symbiotes, who can burrow among the fibers. An individual nest may grow outward as much as 60 centimeters. Moreover, nests usually come in groups, which may carpet whole swaths of the land. "Individual" nests send tendrils out to each other, making it difficult to tell where one ends and the other begins. These complexes always include patches of other mycostrums, however, especially redcap mycostrums, along with ghost mycostrums and either mauvecostrum or pale mycostrum depending on the continent. The bouffant knightworms manage the nest complex's growth to ensure this mix, instinctually nibbling away at the edges when nests are too large or too close to the other flora.
A mature nest grows fruiting bodies, long stalks of condensed fibers that stick out and have pointed caps at their tops. When a nest comes into contact with a genetically distinct individual, it will take in genetic material and use it to fertilize their fruiting bodies. This happens often enough, as neighboring nests in a complex come into contact or as bouffant knightworm's individual mycostrum symbiotes brush against the nest. However, an unfertilized fruiting body is still capable of asexual reproduction. Either way, the fruiting body will grow new strands from its top, which often stream in the wind. When a juvenile bouffant knightworm is ready to leave its nest, it will climb the fruiting body and latch on to one of the strands. On a windy day, the knightworm will sever it from the fruiting body. The strand thins and spreads out into several strands in a triange shape, forming a balloon much the same as in the balloon mycostrum. Caught by the wind, it blows away through the air, carrying the young knightworm with it.
Upon landing, assuming it survives, the ballon form condenses again into a smaller mass of fibers. This rests upon its host's head, forming the "bouffant" that the species are named for. This grows with its host and stays with it for life. It feeds on its host's excess exoskeleton. Furthermore, the hosts often use their bouffants to carry food and water, and they're able to absorb a little bit from that.
New nests grow in one of two ways. If a juvenile bouffant knightworm, after landing and dispersing, is unable to find a nest to join, it will sever part of its personal mycostrum and deposit it on the ground. It then starts fertilizing it by a mix of defecation and the usual chopped-up mycostrums. Lacking support from others, these rarely survive, but some are lucky enough to survive long enough for other knightworms to join the new nest. Additionally, when a bouffant knightworm dies outside its nest, its symbiote will consume its decomposing body and grow into a new nest. This usually happens near enough a nest complex for it to become an extension of the old complex. If far enough away, however, it simply remains available for any bouffant knightworms that come its way. If none do, it dies.
When a bouffant knightworm dies in its nest, it and its symbiote are simply absorbed into the nest. When a nest in a complex dies, it is chopped up to form fertilizer for surviving nests.
Bouffant mycostrums will not survive long without bouffant knightworms. They're a necessary part of their life cycle, and they will not form balloons properly without them. Furthermore, they are unlikely to receive enough nutrients without their hosts' dung, excess eggs and exoskeleton, and the chopped up bits of other mycostrums used to fertilize them.