Dioscorea japonica Thunb.

Japanese yam (en)

Species

Angiosperms > Dioscoreales > Dioscoreaceae > Dioscorea

Characteristics

Tubers vertical, long cylindric, to 3 cm in diam.; cork yellowish brown; transverse section white or yellowish white. Stem twining to right, green, sometimes light purplish red. Bulblets often present. Leaves alternate basally on stem, opposite distally on stem, simple; petiole 1.5--4(--6) cm; leaf blade drying yellowish green to light brownish, broadly ovate basally on stem, usually triangular-lanceolate to linear distally on stem, 3--12(--19) × 1--6(--18) cm, membranous or papery, glabrous, basal veins 5--9, base sagittate or hastate to cordate or ± truncate, margin entire, apex acute to long acuminate. Male spikes 3--5 together, rarely solitary, ± erect or ascending, 2--8 cm; rachis straight, occasionally slightly zigzagged at apex. Male flowers: perianth greenish white or light yellow, lobes purple spotted, ovate or ovate-elliptic, to 2 × 1.5 mm, inner ones smaller than outer; stamens 6. Female spikes solitary or 2 or 3 together, 6--20 cm. Female flowers: staminodes 6. Capsule not reflexed, pale brown with darker, linear freckles, oblate, 1.5--2(--2.5) cm, base truncate, apex emarginate; wings 0.7--1.5(--2) cm wide, margin dark. Seeds inserted near middle of capsule, D-shaped, ca. 1.9 cm (ca. 0.7 cm excluding wing), winged all round. Fl. May--Oct, fr. Jul--Nov.
More
A yam. The stem twines to the right. The tubers are vertical and like a cylinder and 3 cm across. They are brown on the outside and white inside. The lower leaves are alternate and the higher leaves are opposite. They are elongated and irregular and 5-10 cm long by 2-5 cm wide.
Life form perennial
Growth form herb
Growth support climber
Foliage retention deciduous
Sexuality dioecy
Pollination -
Spread -
Mature width (meter) -
Mature height (meter) 4.0
Root system -
Rooting depth (meter) -
Root diameter (meter) -
Flower color
Blooming months
JanFebMar
AprMayJun
JulAugSep
OctNovDec
Fruit color -
Fruiting months
JanFebMar
AprMayJun
JulAugSep
OctNovDec
Nitrogen fixer -
Photosynthetic pathway -

Environment

A temperate to subtropical plant. It grows in high mountains and on the edges of forests. In China it grows on mountain slopes and along river valleys between 100-1,200 m above sea level. It suits hardiness zones 4-10. In Sichuan.
More
Wooded foothills. Mixed forests and margins, scrub forests, herb communities, mountain slopes, valleys, along rivers and streams, roadsides; 100-1200 metres.
Light 7-9
Soil humidity 3-5
Soil texture 3-6
Soil acidity 3-7
Soil nutriment -
Hardiness (USDA) 6-10

Usage

The tubers are cut in slices and boiled. They can be baked. They are grated and eaten with vinegar and added to soups. They can be used as a binding agent for other foods. Vine tips are eaten steamed or stir-fried. The bulbils are cooked and eaten.
Uses food medicinal
Edible leaves roots tubers
Therapeutic use Cough (root), Diarrhea (root), Dyspnea (root), Enteritis (root), Leukorrhea (root), Abdominal pain (tuber), Diarrhea (tuber), Dysentery (tuber), Dyspepsia (tuber), Gastrointestinal diseases (tuber), Abscess (unspecified), Antidiarrheic (unspecified), Antitussive (unspecified), Boil (unspecified), Refrigerant (unspecified), Thirst (unspecified), Tonic (unspecified), Nutrient (unspecified), Restorative (unspecified), Antimutagenic agents (unspecified)
Human toxicity -
Animal toxicity -

Cultivation

It can be grown from the bulbils.
Mode cuttings seedlings
Germination duration (days) 21 - 36
Germination temperacture (C°) 21 - 23
Germination luminosity -
Germination treatment -
Minimum temperature (C°) -
Optimum temperature (C°) -
Size -
Vigor -
Productivity -

Images

Dioscorea japonica unspecified picture

Distribution

Dioscorea japonica world distribution map, present in China, Japan, Korea (Democratic People's Republic of), and Taiwan, Province of China

Identifiers

LSID urn:lsid:ipni.org:names:927492-1
WFO ID wfo-0000391392
COL ID 36CSX
BDTFX ID -
INPN ID -
Wikipedia (EN) Link
Wikipedia (FR) Link

Synonyms

Dioscorea japonica Dioscorea japonica var. kelungensis Dioscorea japonica var. pseudojaponica Dioscorea japonica var. vera Dioscorea japonica var. formosensis Dioscorea japonica var. tenuiaxon Dioscorea kelungensis

Lower taxons

Dioscorea japonica var. japonica Dioscorea japonica var. pilifera