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Hygrophorus Milk Cap - Lactifluus hygrophoroides

Lactifluus hygrophoroides
From this past week at Manitou.

Good evening, friends,

This week’s mushroom is the Hygrophorus Milk Cap (Lactifluus hygrophoroides). A mouthful in both name and dinner, this mushroom fruits abundantly when conditions are right… like right now after more than a foot of rain the past few weeks and more today. A couple years ago I found this mushroom for the first time in Cape Cod. I identified it using the Gary Lincoff Audubon field guide (and an online resource or two). I then threw it on the grill and had one of my most memorable mushroom meals. From edibility to ecology, we’ll learn how the fungus forms substantial relationships with not just our tongues but also the roots of peculiar plants in the soil.

Lactifluus hygrophoroides
The very specimen from Cape Cod in July, 2021.

Fun Facts

This mushroom is referred to as a “milk cap” because of the presence of a milky latex in the cap. It’s suspected that the latex is used as a deterrent for insect foraging as it gums up their mouth. The latex can come in a variety of colors from white to yellow to blue and some even turn different colors. The latex of L. hygrophoroides is white - a characteristic that will help you later differentiate this mushroom from the similar species. The mushroom has a beautiful peach color on the velvety cap and stipe to complement the cream colored gills.

Lactifluus hygrophoroides

I could find only one scientific study that involves L. hygrophoroides and interestingly it details how the fungus may assist in the spread of the invasive Brazilian Peppertree (Schinus terebinthifolia) in Florida. The study sequenced the DNA of organisms found in the Brazilian Peppertree’s rhizosphere (the soil surrounding the plant’s roots) and found that 76.5% of the organisms were ectomycorrhizal fungi (fungi that wrap around the roots to form a symbiotic relationship). Impressively, L. hygrophoroides mycelium comprised more than half of that 76.5%. A substantial symbiont.

That makes sense, right, since they’re looking at the soil right next to the roots you’d imagine a lot of fungi that associate with roots would be in there. However, where it gets really peculiar is that the rhizosphere of the native Firebush (Hamelia patens) only had 2.6% ectomycorrhizal fungi. The invasive pepperbush also had twice as many arbuscular mycorrhizal fungi (fungi that enter the plant roots to form a symbiotic relationship). Further, the invasive peppertree (S. terebinthifolia) had pathogenic fungi comprise just 3.9% of the rhizosphere while the native firebush (H. patens) rhizosphere had 8.1%.

Does L. hygrophoroides and the other fungal associates (or lack thereof) aid the spread of the invasive plant? Likely, yes. However, I want to know if the fungus associates with the invasive so substantially because the plant is already producing more sugars (photosynthesizing more) than the native. That’s my little hypothesis, but more research is needed to unpack this ecological chicken or the egg.

Lactifluus hygrophoroides


The fungus is mycorrhizal and associates with oaks, other hardwoods, and allegedly even hemlocks (per renowned mycologist Walt Sturgeon in Reference 3). L. hygrophoroides grows summer through fall and can be found in eastern North America - but also has iNaturalist observations from Europe and Japan.

There are a few other milk cap mushrooms in the area that resemble L. hygrophoroides, and fortunately there aren’t really any toxic look-a-likes. The Weeping Milk Cap (L. volemus) is similar in color but the gills are closer together (crowded). The white latex of L. volemus stains everything brown, even your fingers, and the mushroom has a fishy odor. A different but similar species, L. corrugis, has a darker, redder cap and darker, more crowded gills.

Two Lactifluus mushrooms growing with different oaks about 100 yards apart. L. Hygrophoides on the right and what I believe to be L. volemus on the left (it smelled fishy).
Two Lactifluus mushrooms growing with different oaks about 100 yards apart. L. Hygrophoides on the right and what I believe to be L. volemus on the left (it smelled fishy).

Mushroom highlights from this past weekend. Thank you to everyone that came out.

A handsome, yellow bolete. Perhaps Retiboletus ornatipes, the Ornate Stalked Bolete. Look at the reticulation on the stipe.

Hypomyces luteovirens
Hypomyces luteovirens infecting the gills and stipe of a Russula, but not afflicting the cap

Galiela Rufa
The gelatinous insides of Galiela Rufa from two Toadstool Tuesdays past.

Walk this weekend

The walk is Sunday, 7/30, at ~10AM with the New York Mycological Society. For the people taking the train from Manhattan, the 8:50 Hudson line train from Grand Central gets to Manitou at 10:04 AM. I’ll meet you at the station and we’ll walk a quarter mile to the preserve. Bring water, some snacks, and either good sneakers or boots. We’ll probably be walking/hiking for several hours but trains back to Manhattan leave every hour from Manitou starting at 1:29 PM.

If you plan on driving let me know because there are only ~3 parking spots at the lower entrance to the preserve. If we have more people driving we’ll just park you at the main preserve entrance where you’ll get to sit in the lap of luxury as I shuttle you down in my 1992 Nissan Pathfinder.

Additionally, the bugs have been hellish. They absolutely dominated me today. When I finally snapped and went hard swatting them I just caught a bee and got stung on the pinky. They dominated me. I’d recommend long-sleeves and bring a bug net for your head if you have one. There isn’t really a bathroom (that isn’t the woods), but I can unlock the office if it’s an emergency.

I attended my last plant propagation class yesterday so next week we’ll return to our regularly scheduled Mushroom Monday to close out July.

Not joking I got bit by multiple mosquitos while writing this. They’re taking victory laps,



1) Kuo, M. (2011, February). Lactarius hygrophoroides. Retrieved from the MushroomExpert.Com Web site:

2) Dawkins K, Esiobu N. Arbuscular and Ectomycorrhizal Fungi Associated with the Invasive Brazilian Pepper Tree (Schinus terebinthifolius) and Two Native Plants in South Florida. Front Microbiol. 2017 Apr 20;8:665. doi: 10.3389/fmicb.2017.00665. PMID: 28473811; PMCID: PMC5397465.


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