Manzanita Bolete
Leccinum manzanitae
Also called manzanita scaber stalk, western red-capped bolete
A large western North American scaber stalk with a deep red-brown, often sticky cap, coarse black scabers on a white stem, and flesh that greys and blackens when cut.
Overview
The Manzanita Bolete is the signature Leccinum of the chaparral and mixed evergreen forests of the Pacific states. Unlike the great majority of scaber stalks, which partner with birch, poplar, oak, or conifers, this species is tied to shrubs and trees in the heath family and its close relatives: manzanita and Pacific madrone.
It is a large and impressive fungus, with caps that can reach twenty centimetres or more and thick white stems roughened by conspicuous black scabers. In wet coastal weather the cap becomes tacky or even slightly slimy, a departure from the dry felted caps typical of the genus and a useful pointer when combined with habitat.
Because manzanita thickets are dense and often occupy dry, rocky slopes, this bolete is a good example of a mycorrhizal fungus adapted to a specialised sclerophyll habitat. Its fruiting is closely tied to the arrival of the winter rains rather than to summer storms, so it appears late in the year compared to most northern scaber stalks.
How to identify it
Cap
The cap is large, commonly 7 to 20 cm across and sometimes broader, convex and thick-fleshed. Colour is a deep red-brown, maroon-brown, or dark brick, sometimes paler and more cinnamon toward the rim. The surface is smooth to finely felted, and characteristically tacky or slightly slimy when wet, drying to a matte finish. A sterile flap of cuticle usually hangs slightly past the tube layer at the margin.
Pores
Tubes are whitish to pale grey when young, ageing dingy buff, brownish, or faintly olive. Pores are minute and round, depressed around the stem apex, and bruise slowly brownish.
Stipe
The stem is stout and firm, 8 to 18 cm tall and often 2 to 4 cm thick, white to pale grey and covered in coarse, prominent scabers that are dark brown to black even on young specimens. It is usually thickest near the middle or base, without a ring, volva, or raised network.
Flesh and spore print
The flesh is white and firm, turning greyish or pinkish-grey on cutting and then darkening progressively toward slate or near black, sometimes with a bluish tinge low in the stem. The spore print is ochre-brown to warm brown.
Where and when it grows
Leccinum manzanitae is restricted to western North America, principally California and adjacent Oregon, with the greatest abundance in coastal and foothill country. It fruits under manzanita in chaparral and in open woodland, and under Pacific madrone in mixed evergreen forest, often on dry rocky or sandy slopes and along the margins of trails and firebreaks.
Its season follows the Mediterranean climate of the region: fruiting begins after the first substantial autumn rains and can continue through winter into early spring in mild coastal areas, in marked contrast to the summer and early-autumn peak of most northern scaber stalks. Fruit bodies push up through duff and leaf litter beneath the shrub canopy, frequently in small scattered groups.
Ecological role
This bolete is ectomycorrhizal with manzanita and madrone. That relationship is notable because most members of the heath family form specialised ericoid mycorrhizas instead, but manzanita and madrone are among the group that maintain conventional ectomycorrhizal partnerships with fungi such as this one, sharing that guild with oaks and pines nearby.
In chaparral, where summers are long, hot, and rainless and soils are thin and rocky, mycorrhizal fungi are critical to host water and nutrient uptake. The fungal mycelium survives the dry season in the soil and responds quickly to autumn rain by producing fruit bodies. After wildfire, mycorrhizal networks associated with resprouting manzanita help the shrubs recover, making fungi like this part of the resilience of the whole ecosystem.
Similar species
Leccinum insigne and other aspen-associated scaber stalks have brighter orange caps that are dry rather than tacky and grow with aspen or birch far from chaparral. Leccinum aurantiacum in the broad sense is comparable in stature but is a poplar associate with paler young scabers and a stronger wine-red flesh phase.
Leccinum armeniacum and other western segregates around this complex differ in cap tone and host, while conifer-associated red-capped scaber stalks are separated by growing under pine or spruce. Any dark-capped Boletus in the same habitat lacks projecting scabers entirely and usually has either a smooth or reticulate stem, which resolves the question at once.