Example ⟳ +
An example collection, so you can see what this page does. Nothing added here is kept: leaving deletes it.

Convolvulus japonicus Thunb.

Convolvulaceae · Kuril Is., China South-Central +5

English names not checked: Wikidata's common names were not read for this page.

Photographs not checked iNaturalist and GBIF media were skipped (not asked) when this page was built. Not asked, or not answered, is not "none": nothing here claims there is none. Why the site says it this way.
Add one to my plants
Sow seed
Habitat figures
Cold floor (1 night in 100)
-11.3°C
Record low -18.3 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
27°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
1,416mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
15–37DLI
Lowest to highest month (DLI) CHELSA
The year in your months, northern hemisphere
  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec
Wet summers: the rain comes May to September, read as a summer growing season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

About the genus · Convolvulus

Convolvulus is a genus of about 200 to 250 species of flowering plants in the bindweed family Convolvulaceae, with a cosmopolitan distribution; the Plants of the World Online database currently accepts 227 species and 12 natural hybrids. Common names include bindweed and morning glory; both are names shared with other closely related genera.

Quoted from Wikipedia, "Convolvulus", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a summer growing season: 70% of the median year's rain (1,070 mm of 1,395 mm) falls in May to September, warmer than the year (wet-season mean 21.3 °C against a yearly mean of 12.0 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: November to March.

Rain

1,395 mm in the median year at the habitat, 1,070 mm of it May to September. Wettest month July at 329 mm, driest month December at 25 mm. Across the grid cells of the range the year's total runs 1,242 mm to 1,706 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,416 mm, is the year's rain at the top of the page; the 1,395 mm here is the median year's, the twelve monthly medians added, which the rain rule reads. Habitat calendar, northern hemisphere; median year across the grid cells of the range, CHELSA.

Light

Open sky over the habitat: 15 to 37 mol/m²/day across the year (daily light integral, median year across the grid cells of the range, CHELSA; the lowest 10th-percentile month across the cells is 14, the highest 90th-percentile month 37).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -11.3 °C, the absolute minimum -18.3 °C, 5,534 frost nights in 44 years, 125.8 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 30.7 °C. Monthly means: the coldest month's mean nightly low -6.7 °C in January (across the grid cells of the range -12.4 °C to -0.6 °C), the warmest month's mean daily high 27.3 °C in August (median year across the grid cells of the range, CHELSA). Cold floor: -11.3 °C, which is the 1st-percentile night over 44 years at a typical spot in the range (NASA POWER).

Humidity

Relative humidity at the habitat: 55 to 67% across the year (monthly means, median year across the grid cells of the range, CHELSA). A figure about the air, saying nothing about how the plant takes water.

How this section is made

Each card states this species' habitat figures with their sources, and what two fixed rules read from them; nothing here says what the plant does, wants or tolerates. The rules · the terms.

Seasons. Read from the median year of CHELSA monthly rainfall and mean temperature across the grid cells of the range: the rain rule takes the smallest set of months carrying 70% of the rain and calls it winter when its mean is more than half a degree below the year's, summer when more than that above, and neither in between; the temperature rule, used only under 120 mm, names the cooler six months when they are at least a degree cooler than the other six. Months are shifted for the other hemisphere only where the temperature curve moves 4 °C or more and the habitat lies 10° or more from the equator. A reading of the curves, not an observation of the plant.

Rain. CHELSA monthly precipitation, median year across the grid cells of the range. The rain that falls where the species is recorded; nothing about how the plant takes water.

Light. CHELSA shortwave radiation at each envelope cell, a daily-mean flux taken to a daily total and converted at 2.07 mol of PAR per MJ. The sky over the habitat, measured; what reaches a plant under a rock, a shrub or a shade cloth is not.

Temperature. NASA POWER daily minima and maxima over 44 years at a typical spot in the range, lapse-corrected +188 m to its elevation; CHELSA monthly means, median year across the grid cells of the range. The cold floor is the 1st-percentile night named in its sentence. Not a measured survival limit for any plant in a pot.

Humidity. CHELSA relative humidity, median year across the grid cells of the range.

Climate across the habitat

Habitat months, northern hemisphere

Habitat climate of Convolvulus japonicus through the yearWarmest months July and August, mean daily high 27 °C; coldest month January, mean nightly low -6.7 °C; 1,395 mm of rain in the median year (the twelve monthly medians added). Medians across the range, from CHELSA; the extremes at the edge from NASA POWER. Habitat months, northern hemisphere.-20°-10°0°10°20°30°40°frost30.7° 99th-percentile day, NASA POWER-18.3° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400500mm rainDLI 15–37RH 55–67%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 464 habitat cells, CHELSA cold quarter: the three months around the coldest month's mean nightly low extremes over 44 years at a typical spot in the range, from NASA POWER, marked at the edge, in no month DLI, mol/m²/dayRH %each on its own scale
Figures by month
JanFebMarAprMayJunJulAugSepOctNovDec
Day °C1 / -2–54 / 2–79 / 6–1116 / 12–1820 / 17–2324 / 21–2727 / 24–2827 / 25–2924 / 21–2518 / 16–2011 / 8–134 / 1–8
Night °C-7 / -12–-1-5 / -9–10 / -3–46 / 4–912 / 9–1417 / 14–1821 / 19–2221 / 19–2416 / 13–209 / 6–152 / -1–8-4 / -7–2
Rain mm28 / 20–4435 / 23–5255 / 44–8178 / 66–121106 / 91–143158 / 129–226329 / 260–414303 / 250–359174 / 150–23253 / 44–7551 / 39–6625 / 19–38
DLI17 / 15–1923 / 22–2429 / 28–3035 / 34–3637 / 36–3735 / 34–3629 / 27–3229 / 27–3226 / 25–2824 / 23–2517 / 16–1915 / 14–17
RH %55 / 52–5855 / 52–5755 / 54–5855 / 53–5958 / 56–6361 / 59–6767 / 65–7166 / 64–6862 / 60–6458 / 56–5957 / 55–5855 / 53–58
How this section is made
Each figure is the median across the 464 grid cells on land that hold in-range records (534 records in those cells; 2 more cells hold records but no land by the elevation layer, so those records sit at sea and the cells are left out), with the 10th–90th percentile span across those cells after the slash where it differs. A dash is a month one or more of those cells has no figure for in the grid (a variable CHELSA does not carry there), so no median is taken rather than one over fewer cells. Extremes and elevation were read at a typical spot in the range, cell 1089:6142 (35.525, 127.125). Over 44 years there: absolute minimum -18.3 °C, 1st-percentile night -11.3 °C, 99th-percentile day 30.7 °C. Normals: CHELSA V2.1 1981–2010 climatology, 0.05° cells (each the mean of ~36 1 km pixels). Across the range: median and 10th–90th percentile of each month across the 464 distinct grid cells holding 534 of the 536 in-range records (2 further cells with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 1089:6142 (its coldest month's mean nightly low nearest the median across cells); its position is the cell centre. Extremes: NASA POWER (MERRA-2) daily 1981–2024, cell 35.50_126.875, lapse-corrected +188 m at 6.5 °C/km. Elevation: ETOPO 2022, 348 m (cell mean).

Natural habitat

Native range as published by WCVP; the marker is where the records are densest and decides nothing: the climate was read across the cells of the in-range records placed well enough to read one, not at the marker.
Openly licensed records inside the range, framed on where they fall.

This species has no GBIF key of its own. Its records are GBIF's under the keys of the names Kew's World Checklist holds as this plant: 2928438 (Convolvulus japonicus Thunb., 38 records), 3676609 (Ipomoea japonica (Thunb.) Roem. & Schult., 0 records), 7324558 (Volvulus japonicus (Thunb.) Farw., 0 records), 7429853 (Calystegia sepium var. japonica (Thunb.) Makino, 735 records), 12107389 (Calystegia japonica (Thunb.) Miq., 3 records). No name was matched to GBIF; the keys are read from Kew's synonymy. How.

NativeKuril Is., China South-Central, Manchuria, China North-Central, China Southeast, Japan, Korea · introduced: Germany, Ontario, Québec, Idaho, Illinois, Kansas, Missouri, Connecticut, Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Pennsylvania, Rhode I., Vermont, West Virginia, New Mexico, Delaware, Kentucky, Maryland, Tennessee, Virginia, District of Columbia · regions are the level-3 units of the World Geographical Scheme for Recording Plant Distributions, as Kew's World Checklist records ranges, some under historical names such as Yugoslavia or Czechoslovakia (how).
Map marker36.834, 127.897 · in the densest population, 383 records (56% of those in range)
Kew's description“climbing perennial” · “temperate” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 679 georeferenced records inside the native range; the climate across the range on the 534 of them in the land cells it reads, of 536 placed to within 10 km; the map shows only the 205 openly licensed ones, which alone would put the marker 39 km away. 33 records outside the WCVP native range not used. 143 in-range records are placed to worse than 10 km, or with no stated accuracy (admitted only as a person's observation to three decimals), and stay on the map but off the climate.
Other GBIF keysRecords also from GBIF's key 2928438 (Convolvulus japonicus Thunb.): Kew's file holds it as Convolvulus japonicus Thunb. (accepted); 38 records, from GBIF's download.Records also from GBIF's key 3676609 (Ipomoea japonica (Thunb.) Roem. & Schult.): Kew's file holds it as Ipomoea japonica (Thunb.) Roem. & Schult. (synonym under Convolvulus japonicus Thunb.); 0 records, from GBIF's search API on the day of the build.Records also from GBIF's key 7324558 (Volvulus japonicus (Thunb.) Farw.): Kew's file holds it as Volvulus japonicus (Thunb.) Farw. (synonym under Convolvulus japonicus Thunb.); 0 records, from GBIF's search API on the day of the build.Records also from GBIF's key 7429853 (Calystegia sepium var. japonica (Thunb.) Makino): Kew's file holds it as Calystegia sepium var. japonica (Thunb.) Makino (synonym under Convolvulus japonicus Thunb.); 735 records, from GBIF's download.Records also from GBIF's key 12107389 (Calystegia japonica (Thunb.) Miq.): Kew's file holds it as Calystegia japonica (Thunb.) Miq. (illegitimate under Convolvulus japonicus Thunb.); 3 records, from GBIF's download.
How this section is made
The map marker: the openly licensed record nearest the middle of the densest 1° population of the 679 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Not checked. iNaturalist and GBIF media were skipped (not asked) when this page was built. Not a statement that none exist.

Similar habitat climate The 6 nearest by mean daily high, mean nightly low and rain, month by month. How.

Quercus dentata Quercus dentata Daimyo oak Photo: CC BY, Jane CharlenChrysanthemum lavandulifolium Chrysanthemum lavandulifolium Asteraceae Photo: CC0, author not statedSophora flavescens Sophora flavescens Shrubby sophora Photo: CC BY, Violetta DzizyurovaSmilax sieboldii Smilax sieboldii Siebold’s greenbrier Photo: CC BY, jimmySalix pierotii Salix pierotii Korean willow Photo: CC BY, Tatyana PetrenkoRibes fasciculatum Ribes fasciculatum Winter-berry currant Photo: CC0, author not stated

Other Convolvulus 45 in the reference

Convolvulus althaeoides Convolvulus althaeoides Mallow-leaved Bindweed Photo: CC BY, Vítor JorgeConvolvulus angustissimus Convolvulus angustissimus Blushing Bindweed Photo: CC BY, Roman SorokaConvolvulus arvensis Convolvulus arvensis Field bindweed Photo: CC BY, Vasco Henrique Oliveira FonsecaConvolvulus assyricus Convolvulus assyricus Convolvulaceae Photo: CC BY, Joey BomConvolvulus boissieri Convolvulus boissieri Convolvulaceae Photo: CC BY, Michael, Antoni and Nihat HinczewskiConvolvulus canariensis Convolvulus canariensis Convolvulaceae Photo: CC BY, Lídia CarreraConvolvulus cantabrica Convolvulus cantabrica Cantabrian Bindweed Photo: CC BY, Noé Fleury FrouartConvolvulus cneorum Convolvulus cneorum Silverbush Photo: CC0, author not stated Convolvulus collinus Convolvulaceae Convolvulus crenatifolius Convolvulus crenatifolius Convolvulaceae Photo: CC BY, Guillermo Huerta RamosConvolvulus × cyprius Convolvulus × cyprius Convolvulaceae Photo: CC BY, Denis OtkydachConvolvulus × despreauxii Convolvulus × despreauxii Convolvulaceae Photo: CC BY-SA, TED all 46 ›

Names & registers

Also known as Ipomoea japonica; Calystegia pubescens; Calystegia japonica f. albiflora; Calystegia japonica f. major; Calystegia subvolubilis f. major and 23 more. (WCVP, RBG Kew)

IPNIPOWOWikidataWFO

The record

Family
Convolvulaceae
Described by
Thunb.
Native to
Kuril Is., China South-Central, Manchuria +4
Wild records
679 in range · 205 open

Every figure here is derived from public data by a stated rule and names its source; nothing about this species is written for its page by a person or by AI, apart from the marked, credited quotations. How →

Where this page came from built 2026-10-22
Kew's names (WCVP) kew.names answeredas of 2026-06-04Kew's entry Convolvulus japonicus Thunb. (plant_name_id 484374), read from Kew's names file
GBIF species record gbif.species not askedGBIF's backbone holds no one accepted species of this name, and a name it holds only as another species' synonym is not taken for this one, so GBIF's records were not asked
GBIF synonyms gbif.synonyms not askedGBIF's backbone holds no one accepted species of this name, and a name it holds only as another species' synonym is not taken for this one, so GBIF's records were not asked
GBIF common names gbif.vernacular not askedGBIF's backbone holds no one accepted species of this name, and a name it holds only as another species' synonym is not taken for this one, so GBIF's records were not asked
WCVP native range wcvp.distribution answeredas of 2026-06-04
GBIF occurrence records gbif.occurrences answeredasked 2026-10-22this species has no GBIF key of its own; its records are read under GBIF's keys for the names Kew's file holds as this plant, never by a name matched; GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21; 38 records of GBIF's key 2928438, Convolvulus japonicus Thunb. (Kew's file holds it as Convolvulus japonicus Thunb. (accepted)): the GBIF download; 0 records of GBIF's key 3676609, Ipomoea japonica (Thunb.) Roem. & Schult. (Kew's file holds it as Ipomoea japonica (Thunb.) Roem. & Schult. (synonym under Convolvulus japonicus Thunb.)): GBIF occurrence search API; 0 records of GBIF's key 7324558, Volvulus japonicus (Thunb.) Farw. (Kew's file holds it as Volvulus japonicus (Thunb.) Farw. (synonym under Convolvulus japonicus Thunb.)): GBIF occurrence search API; 735 records of GBIF's key 7429853, Calystegia sepium var. japonica (Thunb.) Makino (Kew's file holds it as Calystegia sepium var. japonica (Thunb.) Makino (synonym under Convolvulus japonicus Thunb.)): the GBIF download; 3 records of GBIF's key 12107389, Calystegia japonica (Thunb.) Miq. (Kew's file holds it as Calystegia japonica (Thunb.) Miq. (illegitimate under Convolvulus japonicus Thunb.)): the GBIF download; 15 records within 1 km of a botanic garden, herbarium or zoo left out (13 at a botanic garden or arboretum, 2 at a zoo; Wikidata's list)
Habitat climate climate answeredasked 2026-10-22
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-22NASA POWER (MERRA-2) daily 1981–2024, cell 35.50_126.875, lapse-corrected +188 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22found by Kew's IPNI identifier 927293-1, POWO 927293-1
Wikipedia wikipedia nothing to reportasked 2026-10-22
iNaturalist taxon inat.taxon not asked
iNaturalist photographs, wild inat.photos.wild not asked
iNaturalist photographs, cultivated inat.photos.cultivated not asked
GBIF media gbif.media not askedGBIF's backbone holds no one accepted species of this name, and a name it holds only as another species' synonym is not taken for this one, so GBIF's records were not asked
Wikimedia Commons commons nothing to reportasked 2026-10-22
OpenAlex papers openalex not askednot yet asked for this reference; a later fill takes the papers from OpenAlex's snapshot

Every source is recorded as having answered, reported nothing, refused, failed, not been asked, or answered twice where one answer is taken (“not taken: two items answered”), and, for a source asked when this page was built, when: the figures are as the source held them that day; a source read from a file (Kew's World Checklist, a GBIF download) says "as of" the file's day instead; a row carried from an earlier build of the page names that build instead. Only “nothing to report” is ever shown as an absence. Records came from 32 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…