September in the Northern Hemisphere is when the jujubes in the garden start to blush red, and when poria season opens on pine-forest slopes. Poria (bokryeong) is cultivated by burying pine logs and inoculating them with spawn. It also needs a well-drained slope of masato — the coarse, sandy soil left behind as granite weathers. Few city gardeners grow it, then; most of us buy it dried, as chunks, slices, or powder from an herbal-medicine shop, and work with it in the kitchen.
A white lump that grows on pine roots
Poria is a fungus that never raises a cap. Its mycelium gathers on pine roots and stumps, hardens, and builds a mass underground — a sclerotium. The outside is dark and finely wrinkled; the inside is white and firm. Nothing shows above the soil, so there's no telling where one sits until you dig. The kind that's white inside is called baekbokryeong, white poria, and that's mostly what goes into rice cakes, porridge, and tea.
It grows best between 22 and 28°C (72–82°F), and the mycelium runs fastest at the top of that range. The sclerotium overwinters in the ground, but a long rainy summer with standing water will rot it. In the Northern Hemisphere, spawn goes in around April and May, and harvest comes in September and October. China produces the most; Korea and Japan grow it as well, and in the United States it grows wild. Nearly all the poria sold today is cultivated.
What's inside a nearly flavorless mushroom, and what the old books said
White poria is mild enough that it barely alters the taste of whatever it's cooked with. Several research teams have isolated two kinds of compounds from it: pachyman, a beta-glucan polysaccharide, and triterpenes in the pachymic acid family. These studies identify what's present, though — they are not evidence that poria prevents or cures disease.
The Donguibogam, the classic Korean medical compendium, lists poria (茯苓) in its section on woods (木部), calling it neutral in nature — neither cooling nor warming — sweet in taste, and free of toxicity. It also passes along the old account that pine resin sinks into the earth and, after a thousand years, turns into poria. Today poria is classified as the sclerotium of a fungus that grows on pine roots. That's a different explanation, but on one point the old record and the modern classification agree: it comes up alongside pines. Descriptions in historical medical texts should be read as something separate from present-day medical judgment.
Poria's dietary fiber comes from polysaccharides that don't dissolve readily in water. That's likely why the powder is so reluctant to disperse.
Steamed into rice cake
The next time you steam tteok, try working in a little white poria powder. Start at roughly 10 parts rice flour to 1 part poria powder. For 300 g of rice flour, that's about 30 g of poria. Sift the poria through together with the rice flour and it will distribute evenly. The flavor hardly shifts; the texture turns plumper and more substantial.
In porridge, stir it in just before the heat goes off
With juk, or rice porridge, the moment you add the poria powder changes both taste and texture. Let it boil a long while and the porridge turns pasty and dull. Slake the powder in cold water first. Then, once the porridge is nearly done, pour the slurry in right before you turn off the heat and stir it through.
Simmered with jujube and ginger for tea
Try simmering sliced poria with jujube and ginger and drinking it as tea.
- Put the sliced poria, jujubes, and ginger into the water together.
- Simmer about 20 minutes, then strain out the solids.
- The poria slices can be simmered again, up to two more times.
In the cup, the sweetness of the jujube arrives first. Poria contributes almost no flavor of its own, so whatever sweetness the tea has comes mostly from the fruit.
On your porridge day this week, slake a little white poria powder in cold water and stir it in at the very end.
Sources: Donguibogam, woods section (木部), poria (茯苓) · crop information from Nongsaro, Rural Development Administration of Korea
