rhizine (noun, pl. rhizines, variant spelling: sl. rhizina, pl. rhizinae) – a root-like strand of closely agglutinated hyphae on the lower side of a foliose thallus; usually thread-like to intricately branched, scant to more or less numerous; attaching a foliose thallus to its substrate, but unlike a root not participating in nutrient supply; a compact cord of fungal hyphae, with limited (determinate) predominantly apical growth; usually formed as an extension from the lower cortex (cortex-rhizines), rarely originating from the medulla (medulla-rhizines) and secondarily covered by a cortex (corticated medulla-rhizines); of various lengths, thicknesses, colours, and degrees and kinds of branching; usually with a smooth and solid appearance, but rarely fibrous or tomentose (e. g., in Peltigera); the term is sometimes used in a very broad, loose sense for any elongated, root-like structure on the lower surface or even along the margin of foliose thalli, or it is even "misapplied" to cilia (= marginal rhizines) along the thalline margin of apothecia. Related terms: ball-tipped rhizine, cortex-rhizine, corticated medulla-rhizine, medulla rhizine, rhizinose strand, rhizopta. This is:part of lower thallus surface.