Brook Floater vs Coconut Milkcap

Alasmidonta varicosa compared with Lactarius glyciosmus

Key Differences

Brook Floater is Vulnerable while Coconut Milkcap is Least Concern.

Taxonomic Classification

Rank	Brook Floater	Coconut Milkcap
Kingdom	Animalia (Animals)	Fungi (Fungi)
Phylum	Mollusca (Mollusks)	Basidiomycota (Club Fungi)
Class	Bivalvia (Bivalvia)	Agaricomycetes (Mushrooms)
Order	Unionida (Unionida)	Russulales (Russulales)
Family	Unionidae	Russulaceae
Genus	Alasmidonta	Lactarius
Species	Alasmidonta varicosa	Lactarius glyciosmus

Conservation Status

Brook Floater

VU — Vulnerable

Coconut Milkcap

LC — Least Concern

Physical Characteristics

Attribute	Brook Floater	Coconut Milkcap
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Brook Floater

Habitat

Native to North America, inhabiting ecosystems characteristic of the region.

Range

Found in United States. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

Coconut Milkcap

Habitat

Typically found in forest floors, decomposing wood, and soil ecosystems.

Range

Distributed across Belgium, Denmark, Norway, Sweden, and United States.

Brook Floater

The Brook Floater (Alasmidonta varicosa) is a species in the genus Alasmidonta. It is currently classified as Vulnerable on the IUCN Red List. Native to North America, inhabiting ecosystems characteristic of the region.

Coconut Milkcap

The Coconut Milkcap (Lactarius glyciosmus) is a small to medium-sized ectomycorrhizal fungus in the family Russulaceae, recognizable by its pale pinkish-buff or grayish cap and the sweet coconut-like fragrance that gives the species its common name. The cap typically measures 2–6 centimetres across, convex when young and flattening with age, often developing a central depression. Like all milkcaps, it exudes a mild, watery-white latex when the flesh is broken. This fungus forms obligate mycorrhizal associations primarily with birch trees (Betula spp.), making it a characteristic species of northern and montane birch woodlands, heathlands, and mixed deciduous forests. It fruiting bodies emerge from late summer through autumn, pushing up through leaf litter and mossy substrates. Distribution spans cool-temperate regions of Europe, including Scandinavia, the British Isles, and central Europe, extending eastward across Russia and into parts of North America. The species is assessed as Least Concern by the IUCN, reflecting its broad range and stable populations in suitable birch habitats. Ecologically, Lactarius glyciosmus plays a crucial role in forest nutrient cycling, facilitating phosphorus and water uptake for its host trees. The coconut scent, caused by volatile aromatic compounds in the flesh, distinguishes it from similar milkcap relatives such as Lactarius mammosus. It is generally considered inedible due to its mild bitterness, though not toxic.