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Thalassia hemprichii; photograph (c) Nicola Crockford, some rights reserved (CC BY) CC BY(c) Nicola Crockford, some rights reserved (CC BY) · observed growing wild · 2026-02-03

Thalassia hemprichii (Ehrenb.) Asch.

Turtle grass; Species code: Th; Sickle seagrass; Thalassia

Hydrocharitaceae · Egypt, Djibouti +45

Cited as Kew's World Checklist cites it, Thalassia hemprichii (Ehrenb.) Asch.: GBIF's backbone key for this page carries the name with another author, (Ehrenb. ex Solms) Asch.

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Thalassia hemprichii, photograph (c) David Thompson, some rights reserved (CC BY)Thalassia hemprichii, photograph (c) WATANABE Hitoshi 渡辺仁, some rights reserved (CC BY)Thalassia hemprichii, photograph (c) WATANABE Hitoshi 渡辺仁, some rights reserved (CC BY)Thalassia hemprichii, photograph (c) WATANABE Hitoshi 渡辺仁, some rights reserved (CC BY)Thalassia hemprichii, photograph author not stated, no rights reservedThalassia hemprichii, photograph author not stated, no rights reserved 24 photographs ›
Habitat figures
Cold floor (1 night in 100)
21.9°C
Record low 19.1 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
28°C
Jan, Feb, Mar, Apr, Nov and Dec at the habitat CHELSA
Rain a year (median across the range)
1,937mm
10 months of 25 mm or more in the median year CHELSA
Open-sky light
30–43DLI
Lowest to highest month (DLI) CHELSA
The year in the habitat's months, not shifted
  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec
A sharp rainy season, December to April (the habitat's months, not shifted), in a year of even temperature. rain rule, CHELSA
Not shifted: the shift rule does not apply to this habitat. The chart is in the habitat's months.

Summary

Thalassia hemprichii, called Pacific turtlegrass, is a widespread species of seagrass in the family Hydrocharitaceae, native to the shores of the Indian Ocean, the Red Sea, and the western Pacific Ocean. Its growth rate increases with CO2 enrichment, and it can tolerate lowered light conditions caused by algal blooms, allowing for it to respond positively to ocean acidification and other disturbances.

Quoted from Wikipedia, "Thalassia hemprichii", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a sharp season: 70% of the median year's rain (1,260 mm of 1,570 mm) falls in December to April. The temperature curve is flat, 2.7 °C between the warmest and coldest month, so the growing-season rule does not infer a growing season from it. Months are the habitat's, southern hemisphere. The habitat lies within 10° of the equator, where the shift rule does not apply, so they are not shifted for a collection elsewhere.

Rain

1,570 mm in the median year at the habitat, 1,260 mm of it December to April. Wettest month February at 307 mm, driest month September at 12 mm. Across the grid cells of the range the year's total runs 1,141 mm to 2,602 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,937 mm, is the year's rain at the top of the page; the 1,570 mm here is the median year's, the twelve monthly medians added, which the rain rule reads. Habitat calendar, southern hemisphere; median year across the grid cells of the range, CHELSA.

Light

Open sky over the habitat: 30 to 43 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 27, 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 21.9 °C, the absolute minimum 19.1 °C, no frost in 44 years (NASA POWER daily minima). Warmest: the 99th-percentile day is 35.3 °C. Monthly means: the coldest month's mean nightly low 23.9 °C in August (across the grid cells of the range 20.5 °C to 26.2 °C), the warmest month's mean daily high 28.2 °C in January (median year across the grid cells of the range, CHELSA). Cold floor: 21.9 °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: 63 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 -35 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, southern hemisphere

Habitat climate of Thalassia hemprichii through the yearWarmest months January, February, March, April, November and December, mean daily high 28 °C; coldest month August, mean nightly low 23.9 °C; 1,570 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, southern hemisphere.15°20°25°30°35°40°35.3° 99th-percentile day, NASA POWER19.1° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400500mm rainDLI 30–43RH 63–66%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 156 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 °C28 / 27–3028 / 27–3028 / 28–3028 / 27–3027 / 26–3026 / 25–2925 / 24–2925 / 24–2926 / 25–3027 / 26–3128 / 27–3228 / 27–31
Night °C26 / 25–2626 / 25–2626 / 24–2626 / 24–2626 / 23–2625 / 22–2624 / 21–2624 / 21–2625 / 21–2625 / 23–2626 / 24–2626 / 24–26
Rain mm290 / 35–494307 / 30–487278 / 75–384170 / 63–30895 / 21–27944 / 5–25630 / 3–27019 / 5–31112 / 3–30526 / 11–32084 / 49–231215 / 71–285
DLI35 / 31–4035 / 31–4035 / 33–4134 / 32–3932 / 30–3530 / 27–3431 / 28–3535 / 32–3740 / 33–4243 / 30–4643 / 29–4639 / 30–43
RH %65 / 61–6666 / 61–6765 / 61–6764 / 60–6664 / 58–6663 / 57–6563 / 56–6563 / 56–6563 / 56–6563 / 57–6664 / 59–6664 / 61–66
How this section is made
Each figure is the median across the 156 grid cells on land that hold in-range records (549 records in those cells; 125 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 1647:5585 (7.625, 99.275). Over 44 years there: absolute minimum 19.1 °C, 1st-percentile night 21.9 °C, 99th-percentile day 35.3 °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 156 distinct grid cells holding 549 of the 1015 in-range records (125 further cells with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 1647:5585 (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 7.50_99.375, lapse-corrected -35 m at 6.5 °C/km. Elevation: ETOPO 2022, 4 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.
NativeEgypt, Djibouti, Eritrea, Somalia, Sudan, Kenya, Tanzania, Mozambique, Aldabra, Comoros, Madagascar, Seychelles, Saudi Arabia, Yemen, Hainan, Nansei-shoto, Taiwan, India, Laccadive Is., Maldives, Sri Lanka, Andaman Is., Myanmar, Nicobar Is., South China Sea, Thailand, Vietnam, Borneo, Cocos (Keeling) I., Jawa, Lesser Sunda Is., Malaya, Maluku, Philippines, Sulawesi, Sumatera, Bismarck Archipelago, New Guinea, Solomon Is., Northern Territory, Queensland, Western Australia, Gilbert Is., New Caledonia, Caroline Is., Marianas, Marshall Is. · 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 marker-9.878, 142.328 · in the densest population, 691 records (66% of those in range)
Kew's description“rhizomatous hydrogeophyte” · “wet tropical” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 1043 georeferenced records inside the native range; the climate across the range on the 549 of them in the land cells it reads, of 1015 placed to within 10 km; the map shows only the 139 openly licensed ones, which alone would put the marker 10 km away. 5 records outside the WCVP native range not used. 28 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 of the 1043 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Thalassia hemprichii, photograph 1did not loadThalassia hemprichii, photograph 2did not loadThalassia hemprichii, photograph 3did not loadThalassia hemprichii, photograph 4did not loadThalassia hemprichii, photograph 5did not loadThalassia hemprichii, photograph 6did not load

Photographs: (c) David Thompson, some rights reserved (CC BY); (c) WATANABE Hitoshi 渡辺仁, some rights reserved (CC BY) (3); author not stated, no rights reserved · CC0 (2).

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

Manilkara kauki Manilkara kauki Wongai Plum Photo: CC BY, Matt BEnhalus acoroides Enhalus acoroides Species code: Ea Photo: CC0, author not statedMyrmecodia platytyrea Myrmecodia platytyrea Rubiaceae Photo: CC BY, Kristof ZyskowskiXylocarpus moluccensis Xylocarpus moluccensis Cedar mangrove Photo: CC BY, Richard LittauerPremna serratifolia Premna serratifolia Bastard guelder Photo: CC0, author not statedSalacia chinensis Salacia chinensis Celastraceae Photo: CC0, author not stated

Other Thalassia 1 in the reference

Thalassia testudinum Thalassia testudinum Turtle grass Photo: CC BY, Tom Field

Names & registers

Also known as Schizotheca hemprichii. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Hydrocharitaceae
Described by
(Ehrenb.) Asch.
Native to
Egypt, Djibouti, Eritrea +44
Wild records
1043 in range · 139 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 2026-10-22GBIF's key 5329593 is Thalassia hemprichii (Ehrenb. ex Solms) Asch.; the page links Kew's Thalassia hemprichii (Ehrenb.) Asch., and the name is cited as Kew cites it
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; 1 record within 1 km of a botanic garden, herbarium or zoo left out (1 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 7.50_99.375, lapse-corrected -35 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22IPNI and POWO linked by Kew's number for Thalassia hemprichii (Ehrenb.) Asch. (the item's: IPNI 431946-1, POWO 431946-1)
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 2026-10-22none of the photographs on this page is credited to GBIF: those shown are other sources', and GBIF's were the same photographs or were set aside by the photograph rules
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

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