Rooting Cauliflower

Rooting Cauliflower is the western North American cauliflower fungus, and it can be a genuinely imposing find — well-grown specimens reach 50 cm across and can weigh many kilograms, appearing as a pale, ruffled mass at the foot of a Douglas-fir or pine. Its name comes from the long, tapering, root-like base that runs down from the rosette into the soil to reach a colonised conifer root, sometimes 10 to 20 cm below the surface.

Sparassis sits in the family Sparassidaceae within the Polyporales, so its relatives are the bracket and crust polypores rather than the corals it superficially recalls. The genus is defined by a rosette of flattened lobes with a smooth fertile surface, in place of gills, pores or teeth.

Taxonomically the western fungus has had an unstable history. It has been treated as Sparassis radicata, as a form of the European Sparassis crispa, and more recently molecular work has variously separated and reunited the western and European populations. Field guides in North America still widely use the radicata name for its distinctive long rooting base and conifer association.

Fruiting body

A large, rounded to lobed rosette 15 to 50 cm across and 10 to 30 cm tall, composed of many flattened, wavy, ribbon-like lobes arising from a common core. Lobes are 1 to 5 cm wide, thin, and curled or crisped, giving the whole structure a loosely packed, egg-noodle or lettuce-like appearance with abundant air space between the folds.

Colour

Cream, pale yellow or whitish when fresh, with the edges of the lobes yellowing then browning as they age or dry. The oldest interior lobes discolour ochre to tan. Fresh specimens have a soft, slightly waxy sheen.

Base

The defining feature is the base: a tough, whitish to pale tan tapering root that extends well down into the soil to a conifer root or buried wood. Digging the specimen out reveals this stalk-like extension, which is far more pronounced than the short pad of S. spathulata.

Flesh and spore print

The flesh is white, firm and slightly elastic, tougher at the base and thin and pliant at the lobe margins. The fertile surface is smooth and coats the underside of each lobe; there are no pores, gills or teeth. The spore print is white to pale yellow, and the spores are small, smooth and elliptical.

Rooting Cauliflower fruits at the base of living and recently dead conifers, most commonly Douglas-fir, and also with pines, spruce and other softwoods. It emerges from the ground near the trunk, from exposed roots, or from stumps, and the rooting base always leads back to woody tissue even when no wood is visible at the surface.

The season is late summer through autumn, typically September to November on the Pacific coast, with fruiting following the return of autumn rains. Its range covers western North America from British Columbia and the Pacific Northwest south through Oregon, California and into the Rocky Mountain conifer belt. Established mycelium can produce a rosette at the same tree base annually for a decade or more, and known fruiting spots are often remarkably consistent.

Sparassis radicata is a root and butt-rot fungus of conifers, entering through wounds or dead roots and behaving as a weak parasite before continuing as a saprotroph on the same tissue after the host dies. It causes a brown rot: cellulose and hemicellulose are removed while lignin remains, leaving root and butt wood brown, friable and cracked into cubical blocks.

Because the decay is centred on roots and the lowest metre of trunk, an infected tree may remain standing and outwardly unchanged for years while its anchorage is progressively weakened, making the fungus of some interest to forest pathologists. The long rooting base is a direct physical link between the surface rosette and that buried, colonised wood. Ecologically, the fungus is part of the community that returns large woody root systems to the forest soil, and the dense folded lobes of its fruiting body maximise the spore-bearing surface available near ground level.

Sparassis spathulata of eastern North America has broader, flatter, leaf-like lobes with faint concentric zoning, a short basal pad rather than a long taproot, and grows with oaks and other hardwoods. Sparassis crispa of Europe has similarly crisped ribbon lobes and a conifer host but a shorter base, and the two have often been considered conspecific.

Grifola frondosa and Meripilus species can form comparably large rosettes at tree bases but are built from thick overlapping fan-shaped caps with pored undersides, and they favour hardwoods; checking the underside of a lobe for pores separates them at once. Hericium species growing at conifer wounds produce hanging spines rather than flattened lobes. Where a Sparassis is old and browned, the smooth fertile surface, the elastic white flesh and the tapering rooting base remain reliable characters.