This preprint documents an original experimental framework for inducing mycorrhizal symbiotic behavior in ectomycorrhizal fungi under entirely hostless laboratory conditions. The work introduces the novel term Cassorrhizal — defined as a state of false colonization where fungal mycelium is chemically or physically lured into a symbiotic response by a non-living, deceptive, or non-existent root structure — and describes the J160 media series developed to replicate the chemical, mechanical, and osmotic environment of a living root without one being present. The framework covers the multi-role chemistry of a purpose-formulated low acyl gellan gum matrix as a root tissue analog, a pH-buffered TCA cycle entry point carbon system, hemicellulose signaling compounds, osmotic turgor management, and flavonoid-mediated pre-symbiotic effector induction via rutin hydrothermal conversion. The experimental isolate is a suspected Lactarius rubidus, though the framework is designed to apply broadly to ectomycorrhizal species. The target phenotype is Hartig net formation or attempted formation in the absence of a living host.