Chinese yam is an East Asian food vine that has escaped from gardens and become an invasive weed in much of the eastern United States. It is easiest to spot by the small, warty "mini potatoes" () hanging where the leaves meet the stem. It is also called cinnamon vine for its cinnamon-scented flowers.
Appearance
- Appearance
- The underground tuber can reach about 3 ft (1 m) deep and weigh about 10 lb (4.5 kg).
- Growth form
- A twining perennial vine that dies back in winter. It can smother shrubs and trees, and the old dead vines act as a trellis for new growth.
- Leaves
- Heart-shaped to triangular leaves, up to about 4½ in (11 cm) long, glossy and slightly quilted on top. They may be alternate, opposite, or in whorls on the same vine, and the stems are angled rather than round.
- Flowers
- Tiny greenish-white flowers in spikes, May to August in the U.S., with a cinnamon scent.
Look-alikes
Air potato has round stems, leaves that are always alternate with broadly rounded bases, and smooth bulbils up to 5 in (13 cm) long. Chinese yam has angled stems, a mix of alternate and opposite leaves, and small warty bulbils about 1 in (2.5 cm) or less.
Why they get mixed upBoth are invasive yam vines that hang potato-like bulbils from the leaf joints. Air potato is mostly in Florida and nearby states.
Where it lives
- Typical habitats
- forest edges
- stream banks
- disturbed ground
- Range
- Native to East Asia. Brought to the U.S. in the 1800s, it now grows wild across much of the eastern U.S. It is listed as invasive in many eastern states, including Kentucky, Tennessee, and Virginia.
- Preferred conditions
- Grows fast in open to partly shaded spots and does best in moist, disturbed places. Hardy in USDA zones 5–9.
- Flowering
Flowers May–Aug
Flowers May–Aug · Fruit Jun–Sep
Growing it
- Propagation
- Spreads mainly by bulbils, which drop off, wash downstream, and sprout into new plants. Gardeners often move them around without knowing, because the dangling bulbils look interesting.
- Toxicity
- The tuber is edible raw, which is unusual for a yam, but the skin holds oxalate crystals that can make hands itch.
Conservation
- IUCN Red List
- NENot EvaluatedNot yet assessed
- Status
- New York lists it as a prohibited invasive plant, so it may not be sold, propagated, or transported there.
Culture and stories
- Culture and stories
- In Japan the grated tuber, called tororo, is served over rice or noodles; in China and Korea it is eaten raw, steamed, in soups, or blended into a drink.
More species to explore
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