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Digitaria ciliaris; photograph (c) WATANABE Hitoshi 渡辺仁, some rights reserved (CC BY) CC BY(c) WATANABE Hitoshi 渡辺仁, some rights reserved (CC BY) · observed growing wild · 2026-09-23

Digitaria ciliaris (Retz.) Koeler

Southern crabgrass; Tropical finger-grass; Common crabgrass; Crabgrass

Poaceae · Algeria, Egypt +89

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Digitaria ciliaris, photograph (c) WATANABE Hitoshi 渡辺仁, some rights reserved (CC BY)Digitaria ciliaris, photograph (c) WATANABE Hitoshi 渡辺仁, some rights reserved (CC BY)Digitaria ciliaris, photograph (c) WATANABE Hitoshi 渡辺仁, some rights reserved (CC BY)Digitaria ciliaris, photograph (c) 大澤風季 ohsawa_Fuki, some rights reserved (CC BY)Digitaria ciliaris, photograph (c) Julien, some rights reserved (CC BY)Digitaria ciliaris, photograph (c) Julien, some rights reserved (CC BY) 101 photographs ›
Habitat figures
Cold floor (1 night in 100)
4.5°C
Record low 0.3 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
28°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
1,411mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
17–37DLI
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 March and 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.

Summary

Digitaria ciliaris is a species of grass known by the common names southern crabgrass, tropical finger-grass, tropical crabgrass or summer grass.

Quoted from Wikipedia, "Digitaria ciliaris", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a summer growing season: 70% of the median year's rain (914 mm of 1,240 mm) falls in March and May to September, warmer than the year (wet-season mean 21.4 °C against a yearly mean of 18.5 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: November to March and September.

Rain

1,240 mm in the median year at the habitat, 914 mm of it March and May to September. Wettest month August at 221 mm, driest month December at 33 mm. Across the grid cells of the range the year's total runs 381 mm to 2,505 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,411 mm, is the year's rain at the top of the page; the 1,240 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: 17 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 12, the highest 90th-percentile month 46).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is 4.5 °C, the absolute minimum 0.3 °C, no frost in 44 years (NASA POWER daily minima). Warmest: the 99th-percentile day is 44.9 °C. Monthly means: the coldest month's mean nightly low 11.4 °C in January (across the grid cells of the range -8.9 °C to 18.3 °C), the warmest month's mean daily high 28.3 °C in August (median year across the grid cells of the range, CHELSA). Cold floor: 4.5 °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: 56 to 66% 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 +42 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 Digitaria ciliaris through the yearWarmest months July and August, mean daily high 28 °C; coldest month January, mean nightly low 11.4 °C; 1,240 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.-10°0°10°20°30°40°50°frost44.9° 99th-percentile day, NASA POWER0.3° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400mm rainDLI 17–37RH 56–66%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 236 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 °C15 / 1–3015 / 3–3415 / 8–3718 / 14–4022 / 17–4126 / 19–3928 / 21–3528 / 22–3325 / 21–3621 / 17–3718 / 10–3516 / 3–32
Night °C11 / -9–1812 / -7–2013 / -2–2214 / 4–2516 / 10–2719 / 15–2822 / 18–2622 / 19–2521 / 15–2518 / 8–2415 / 1–2112 / -5–19
Rain mm38 / 0–17956 / 0–17381 / 1–19181 / 2–194101 / 11–253141 / 39–332201 / 44–379221 / 60–351169 / 58–32262 / 10–21156 / 0–18033 / 0–197
DLI18 / 14–3823 / 19–4130 / 26–4435 / 32–4637 / 33–4635 / 30–4433 / 28–4332 / 28–4129 / 25–4125 / 20–4019 / 15–3917 / 12–37
RH %56 / 33–6556 / 30–6557 / 30–6558 / 34–6660 / 40–6664 / 47–6866 / 54–7065 / 58–6963 / 54–6759 / 43–6557 / 35–6456 / 34–64
How this section is made
Each figure is the median across the 236 grid cells on land that hold in-range records (372 records in those cells; 3 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 1302:5110 (24.875, 75.525). Over 44 years there: absolute minimum 0.3 °C, 1st-percentile night 4.5 °C, 99th-percentile day 44.9 °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 236 distinct grid cells holding 372 of the 376 in-range records (3 further cells with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 1302:5110 (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 25.00_75.625, lapse-corrected +42 m at 6.5 °C/km. Elevation: ETOPO 2022, 419 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.
NativeAlgeria, Egypt, Libya, Azores, Canary Is., Cape Verde, Benin, Burkina, The Gambia, Ghana, Guinea-Bissau, Guinea, Ivory Coast, Liberia, Mali, Mauritania, Nigeria, Niger, Senegal, Sierra Leone, Central African Republic, Cameroon, Congo, Zaïre, Chad, Djibouti, Eritrea, Ethiopia, Socotra, Somalia, Sudan, Kenya, Tanzania, Uganda, Angola, Mozambique, Zimbabwe, Botswana, Cape Provinces, KwaZulu-Natal, Free State, Swaziland, Northern Provinces, Ascension, Aldabra, Mauritius, Madagascar, Réunion, Rodrigues, Seychelles, Kuril Is., Transcaucasus, Palestine, Sinai, Turkey, Gulf States, Kuwait, Oman, Saudi Arabia, Yemen, China South-Central, Hainan, Inner Mongolia, Manchuria, China North-Central, China Southeast, Tibet, Xinjiang, Japan, Korea, Kazan-retto, Nansei-shoto, Ogasawara-shoto, Taiwan, Assam, Bangladesh, East Himalaya, India, Laccadive Is., Nepal, Pakistan, Sri Lanka, West Himalaya, Cambodia, Laos, Myanmar, South China Sea, Thailand, Vietnam, Lesser Sunda Is., Malaya · introduced: Great Britain, Austria, Czechoslovakia, Germany, Portugal, Sardegna, Spain, Bulgaria, Greece, Italy, East European Russia, Madeira, St.Helena, Primorye, Andaman Is., Nicobar Is., Jawa, New Guinea, Solomon Is., Norfolk Is., New South Wales, Northern Territory, Queensland, South Australia, Tasmania, Victoria, Western Australia, Kermadec Is., New Zealand North, New Zealand South, Fiji, Nauru, Niue, New Caledonia, Phoenix Is., Samoa, Tonga, Vanuatu, Wallis-Futuna Is., Cook Is., Easter Is., Marquesas, Society Is., Tuamotu, Tubuai Is., Caroline Is., Marcus I., Marianas, Marshall Is., Wake I., Hawaii, Ontario, Illinois, Iowa, Kansas, Missouri, Nebraska, Oklahoma, Connecticut, Indiana, Massachusetts, New Jersey, New York, Ohio, Pennsylvania, Vermont, Arizona, California, Utah, New Mexico, Texas, Alabama, Arkansas, Delaware, Florida, Georgia, Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, District of Columbia, Mexico Central, Mexico Northeast, Mexico Gulf, Mexico Northwest, Mexico Southwest, Mexico Southeast, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama, Aruba, Bahamas, Cayman Is., Cuba, Dominican Republic, Haiti, Jamaica, Leeward Is. AB Ant, Netherlands Antilles, Puerto Rico, Turks-Caicos Is., Trinidad-Tobago, Venezuelan Antilles, Windward Is., French Guiana, Guyana, Surinam, Venezuela, Bolivia, Colombia, Ecuador, Galápagos, Peru, Brazil West-Central, Brazil Northeast, Brazil Southeast, Brazil North, Brazil South, Argentina Northeast, Argentina Northwest, Chile Central, Chile North, Paraguay, Uruguay · 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 marker35.499, 139.391 · in the densest population, 218 records (26% of those in range)
Kew's description“annual or perennial” · “seasonally dry tropical” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 852 georeferenced records inside the native range; the climate across the range on the 372 of them in the land cells it reads, of 376 placed to within 10 km; the map shows only the 699 openly licensed ones, which alone would put the marker in the same place. 792 records outside the WCVP native range not used. 476 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.
How this section is made
The map marker: the openly licensed record nearest the middle of the densest 1° population inside the densest 4° block of the 852 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Digitaria ciliaris, photograph 1did not loadDigitaria ciliaris, photograph 2did not loadDigitaria ciliaris, photograph 3did not loadDigitaria ciliaris, photograph 4did not loadDigitaria ciliaris, photograph 5did not loadDigitaria ciliaris, photograph 6did not load

Photographs: (c) WATANABE Hitoshi 渡辺仁, some rights reserved (CC BY) (3); (c) 大澤風季 ohsawa_Fuki, some rights reserved (CC BY); (c) Julien, some rights reserved (CC BY) (2).

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

Ampelopsis glandulosa Ampelopsis glandulosa Amur peppervine Photo: CC BY-SA, Douglas GoldmanCarex wahuensis Carex wahuensis Oahu sedge Photo: CC0, author not statedPilea peploides Pilea peploides Pacific Island clearweed Photo: CC BY, 胡正恆(Jackson Hu)Ficus erecta Ficus erecta Erect fig Photo: CC BY, Francisca WuYoungia japonica Youngia japonica Oriental false hawksbeard Photo: CC BY, Milo CatonOnychium japonicum Onychium japonicum Carrot fern Photo: CC BY, Yinling Chen

Other Digitaria 9 in the reference

Digitaria californica Digitaria californica Arizona cottontop Photo: CC BY, Mark PollockDigitaria cognata Digitaria cognata Fall witchgrass Photo: CC BY, Peter QuakenbushDigitaria didactyla Digitaria didactyla Blue couch Photo: CC0, author not statedDigitaria eriantha Digitaria eriantha Pangola-grass Photo: CC0, author not statedDigitaria henryi Digitaria henryi Poaceae Photo: CC BY-SA, KeisotyoDigitaria insularis Digitaria insularis Sourgrass Photo: CC0, author not statedDigitaria ischaemum Digitaria ischaemum Smooth finger grass Photo: CC0, author not statedDigitaria radicosa Digitaria radicosa Trailing crabgrass Photo: CC BY, chiuluanDigitaria sanguinalis Digitaria sanguinalis Hairy finger-grass Photo: CC0, author not stated

Names & registers

Also known as Asprella digitaria; Asprella digitata; Digitaria abortiva; Digitaria adscendens; Digitaria adscendens subsp. adscendens and 105 more. (GBIF Backbone)

Kew accepts as species of their own Digitaria henryi: older names in GBIF's record of this species that Kew's World Checklist accepts as other species. (WCVP, RBG Kew, file of 2026-06-04)

Under another author Panicum brevifolium (Link) Kunth is an older name of this species, not Panicum brevifolium, a species of the reference. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Poaceae
Described by
(Retz.) Koeler
Native to
Algeria, Egypt, Libya +88
Wild records
852 in range · 699 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
GBIF species record gbif.species answeredasked 2026-10-22
GBIF synonyms gbif.synonyms answeredasked 2026-10-22
GBIF common names gbif.vernacular answeredasked 2026-10-22names fetched 2026-10-22
WCVP native range wcvp.distribution answeredas of 2026-06-04
GBIF occurrence records gbif.occurrences answeredas of 2026-10-21GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21; 37 records within 1 km of a botanic garden, herbarium or zoo left out (26 at a botanic garden or arboretum, 5 at a herbarium, 6 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 25.00_75.625, lapse-corrected +42 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22IPNI and POWO linked by Kew's number for Digitaria ciliaris (Retz.) Koeler (the item's: IPNI 70030121-1, POWO 1038558-2)
Wikipedia wikipedia answeredasked 2026-10-22
iNaturalist photographs, wild inat.photos.wild answeredasked 2026-10-22from iNaturalist's open data of 2026-09-27: research-grade observations with an open-licence photograph, the 24 whose photographs iNaturalist received last (the open data holds no votes); filled 2026-10-22
iNaturalist photographs, cultivated inat.photos.cultivated not asked
GBIF media gbif.media answeredasked 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 275 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…